diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
new file mode 100644
index 000000000..7fbb2a885
--- /dev/null
+++ b/.github/CODEOWNERS
@@ -0,0 +1,12 @@
+# Default to requesting pull request reviews from the Heroku Languages team.
+#ECCN:Open Source
+#GUSINFO:Heroku - Languages,Heroku Ruby Platform
+* @heroku/languages
+
+# However, request review from the language owner instead for files that are updated
+# by Dependabot or release automation, to reduce team review request noise.
+CHANGELOG.md @schneems
+Gemfile.lock @schneems
+/.github/workflows/ @schneems
+/changelogs/ @schneems
+/lib/language_pack/version.rb @schneems
diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 000000000..8fcdec8d6
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,24 @@
+version: 2
+updates:
+  - package-ecosystem: "bundler"
+    directory: "/"
+    open-pull-requests-limit: 1 # Limit concurrent CI runs from executing, do not remove
+    schedule:
+      interval: "monthly"
+    labels:
+      - "dependencies"
+      - "ruby"
+      - "skip changelog"
+    groups:
+      ruby-dependencies:
+        update-types:
+          - "minor"
+          - "patch"
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "monthly"
+    labels:
+      - "dependencies"
+      - "github actions"
+      - "skip changelog"
diff --git a/.github/workflows/check_changelog.yml b/.github/workflows/check_changelog.yml
new file mode 100644
index 000000000..240c20261
--- /dev/null
+++ b/.github/workflows/check_changelog.yml
@@ -0,0 +1,20 @@
+name: Check Changelog
+
+on:
+  pull_request:
+    types: [opened, reopened, labeled, unlabeled, synchronize]
+
+permissions:
+  contents: read
+
+jobs:
+  check-changelog:
+    runs-on: ubuntu-latest
+    if: (!contains(github.event.pull_request.labels.*.name, 'skip changelog'))
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v7
+      - name: Check that CHANGELOG is touched
+        run: |
+          git fetch origin ${{ github.base_ref }} --depth 1 && \
+          git diff remotes/origin/${{ github.base_ref }} --name-only | grep CHANGELOG.md
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 000000000..754e06ac5
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,56 @@
+name: CI
+
+on:
+  push:
+    # Avoid duplicate builds on PRs.
+    branches:
+      - main
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v7
+      - name: Install Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          bundler-cache: true
+          ruby-version: "3.3.9"
+      - name: Run StandardRB
+        run: bundle exec standardrb
+      - name: Run ShellCheck bin top level
+        run: |
+            # All bash files that don't end in '.rb'
+            # https://git-scm.com/docs/gitglossary#Documentation/gitglossary.txt-aiddefpathspecapathspec
+            git ls-files -z --cached --others --exclude-standard ':(exclude)*.rb' 'bin/*' '*/bin/*' '*.sh' | \
+              xargs -0 shellcheck --check-sourced --color=always
+
+  integration-test:
+      runs-on: ubuntu-24.04
+      env:
+        HATCHET_APP_LIMIT: 300
+        HATCHET_EXPENSIVE_MODE: 1
+        HEROKU_API_KEY: ${{ secrets.HEROKU_API_KEY }}
+        HEROKU_API_USER: ${{ secrets.HEROKU_API_USER }}
+        RAILS_LTS_CREDS: ${{ secrets.RAILS_LTS_CREDS }}
+        HEROKU_DISABLE_AUTOUPDATE: 1
+        PARALLEL_SPLIT_TEST_PROCESSES: 85
+        RSPEC_RETRY_RETRY_COUNT: 1
+      steps:
+        - name: Checkout
+          uses: actions/checkout@v7
+        - name: Install Ruby and dependencies
+          uses: ruby/setup-ruby@v1
+          with:
+            bundler-cache: true
+            ruby-version: "3.3.9"
+        - name: Hatchet setup
+          run: bundle exec hatchet ci:setup
+        - name: Run Hatchet integration tests
+          # parallel_split_test runs rspec in parallel, with concurrency equal to PARALLEL_SPLIT_TEST_PROCESSES.
+          run: bundle exec parallel_split_test spec/
diff --git a/.github/workflows/document_ruby_version.yml b/.github/workflows/document_ruby_version.yml
new file mode 100644
index 000000000..8eda9a650
--- /dev/null
+++ b/.github/workflows/document_ruby_version.yml
@@ -0,0 +1,43 @@
+name: Add Ruby version to changelog && prepare release
+run-name: "Add ${{ inputs.is_jruby && 'J' || ''}}Ruby ${{ inputs.ruby_version }} to the CHANGELOG.md and prepare a release"
+
+on:
+  workflow_dispatch:
+    inputs:
+      ruby_version:
+          description: "The Ruby version to announce"
+          type: string
+          required: true
+      is_jruby:
+          description: "JRuby release? (as opposed to MRI)"
+          type: boolean
+          default: false
+          required: false
+
+# Disable all GITHUB_TOKEN permissions, since the GitHub App token is used instead.
+permissions: {}
+
+jobs:
+  prepare-release:
+    uses: heroku/languages-github-actions/.github/workflows/_classic-buildpack-prepare-release.yml@latest
+    secrets: inherit
+    with:
+      custom_update_command: |
+        set -euo pipefail
+        DATE_TODAY="$(date --utc --iso-8601)"
+
+        sed --in-place "/## \[v${NEW_VERSION}\] - ${DATE_TODAY}/a\\
+        \\
+        - ${{ inputs.is_jruby && 'J' || ''}}Ruby ${{inputs.ruby_version}} is now available" CHANGELOG.md
+
+        sed --in-place --regexp-extended \
+          --expression "s/v${EXISTING_VERSION}/v${NEW_VERSION}/" \
+          lib/language_pack/version.rb
+
+        if compgen -G 'changelogs/unreleased/*.md' > /dev/null; then
+          # The unreleased changelogs directory contains a `.gitkeep` file, so we have to
+          # copy the markdown files individually instead of renaming the directory.
+          NEW_CHANGELOG_DIR="changelogs/v${NEW_VERSION}/"
+          mkdir -p "${NEW_CHANGELOG_DIR}"
+          mv changelogs/unreleased/*.md "${NEW_CHANGELOG_DIR}"
+        fi
diff --git a/.github/workflows/hatchet_app_cleaner.yml b/.github/workflows/hatchet_app_cleaner.yml
new file mode 100644
index 000000000..974e30d42
--- /dev/null
+++ b/.github/workflows/hatchet_app_cleaner.yml
@@ -0,0 +1,31 @@
+name: Hatchet app cleaner
+
+on:
+  schedule:
+    # Daily at 6am UTC.
+    - cron: "0 6 * * *"
+  # Allow the workflow to be manually triggered too.
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  hatchet-app-cleaner:
+    runs-on: ubuntu-latest
+    env:
+      HEROKU_API_KEY: ${{ secrets.HEROKU_API_KEY }}
+      HEROKU_API_USER: ${{ secrets.HEROKU_API_USER }}
+      HEROKU_DISABLE_AUTOUPDATE: 1
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v7
+      - name: Install Ruby and dependencies
+        uses: ruby/setup-ruby@v1
+        with:
+          bundler-cache: true
+          ruby-version: "3.3.9"
+      - name: Run Hatchet destroy
+        # Only apps older than 10 minutes are destroyed, to ensure that any
+        # in progress CI runs are not interrupted.
+        run: bundle exec hatchet destroy --older-than 10
diff --git a/.github/workflows/prepare-release.yml b/.github/workflows/prepare-release.yml
new file mode 100644
index 000000000..2e6ff4c71
--- /dev/null
+++ b/.github/workflows/prepare-release.yml
@@ -0,0 +1,27 @@
+name: Prepare Release
+
+on:
+  workflow_dispatch:
+
+# Disable all GITHUB_TOKEN permissions, since the GitHub App token is used instead.
+permissions: {}
+
+jobs:
+  prepare-release:
+    uses: heroku/languages-github-actions/.github/workflows/_classic-buildpack-prepare-release.yml@latest
+    secrets: inherit
+    with:
+      custom_update_command: |
+        set -euo pipefail
+
+        sed --in-place --regexp-extended \
+          --expression "s/v${EXISTING_VERSION}/v${NEW_VERSION}/" \
+          lib/language_pack/version.rb
+
+        if compgen -G 'changelogs/unreleased/*.md' > /dev/null; then
+          # The unreleased changelogs directory contains a `.gitkeep` file, so we have to
+          # copy the markdown files individually instead of renaming the directory.
+          NEW_CHANGELOG_DIR="changelogs/v${NEW_VERSION}/"
+          mkdir -p "${NEW_CHANGELOG_DIR}"
+          mv changelogs/unreleased/*.md "${NEW_CHANGELOG_DIR}"
+        fi
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
new file mode 100644
index 000000000..67261321d
--- /dev/null
+++ b/.github/workflows/release.yml
@@ -0,0 +1,36 @@
+name: Release Buildpack
+
+on:
+  # Auto-trigger when the "Prepare release" PR (created by the
+  # _classic-buildpack-prepare-release.yml workflow) is merged.
+  pull_request:
+    branches:
+      - main
+    types:
+      - closed
+  workflow_dispatch:
+
+permissions:
+  id-token: write
+  contents: write
+
+jobs:
+  release:
+    name: Release
+    # On `pull_request`, only run for the merged auto-generated
+    # "Prepare release" PR (branch name set by
+    # _classic-buildpack-prepare-release.yml). Manual dispatches always run.
+    if: >-
+      github.event_name == 'workflow_dispatch' ||
+      (github.event.pull_request.merged == true &&
+       github.event.pull_request.head.repo.full_name == github.repository &&
+       github.event.pull_request.head.ref == 'prepare-release' &&
+       github.event.pull_request.user.login == 'heroku-linguist[bot]')
+    uses: heroku/languages-github-actions/.github/workflows/_classic-buildpack-publish.yml@latest
+    with:
+      buildpack_id: "heroku/ruby"
+      app_id: ${{ vars.LINGUIST_GH_APP_ID }}
+    secrets:
+      app_private_key: ${{ secrets.LINGUIST_GH_PRIVATE_KEY }}
+      slack_webhook_url: ${{ secrets.BUILDPACK_RELEASE_FAILURE_WEBHOOK_URL }}
+      honeycomb_api_key: ${{ secrets.HONEYCOMB_API_KEY }}
diff --git a/.gitignore b/.gitignore
index d3c5516c2..79d3e9fdc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,3 +6,6 @@ vendor/bundle/*
 .ruby-version
 buildpacks/*
 .anvil/
+tmp/*.log
+log/*.log
+spec/examples.txt
diff --git a/.rspec b/.rspec
new file mode 100644
index 000000000..e69de29bb
diff --git a/.standard.yml b/.standard.yml
new file mode 100644
index 000000000..f2d6f73eb
--- /dev/null
+++ b/.standard.yml
@@ -0,0 +1,7 @@
+# StandardRB configuration
+# https://github.com/standardrb/standard
+
+ignore:
+  - "repos/**/*"  # Test fixture repos (external Rails apps for integration tests)
+  - "lib/language_pack/ruby.rb":
+    - Lint/IneffectiveAccessModifier  # Class methods after `private` are intentionally public; private only affects instance methods
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index d994c0faf..000000000
--- a/.travis.yml
+++ /dev/null
@@ -1,23 +0,0 @@
----
-language: ruby
-rvm:
-- 2.0.0
-
-before_script: bundle exec rake hatchet:setup_travis
-
-# Run tests in parallel
-script: bundle exec parallel_rspec -n 11 spec/
-
-after_script:
-  - heroku keys:remove ~/.ssh/id_rsa
-
-env:
-  global:
-  - HATCHET_RETRIES=3
-  - IS_RUNNING_ON_TRAVIS=true
-  - HATCHET_DEPLOY_STRATEGY=git
-  # sets the HEROKU_API_KEY to a dummy user for Heroku deploys
-  - secure: |-
-      ccqb7fKumq2+VEkSrkCqmLjALj5R/ZDgAQGZULSFYeD0O0man3hezUEbMB53
-      U+7gLkbqz5saFX9S5Sz26f99vmhWz1bMHkC2UtlyFSlgaqSvXMZNHJAweqRY
-      ptqugqtvT0VVl1g3DInVgjDZhjINICv/CIorNuHijOFanP1Zmxg=
diff --git a/CHANGELOG.md b/CHANGELOG.md
index e9a0caf34..4d9a1dc88 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,1239 @@
-## Master
+# Changelog
 
-## v108 (2/27/2014)
+## [Unreleased]
+
+
+## [v362] - 2026-08-25
+
+- Yarn is now downloaded from the npm registry instead of the `heroku-nodebin` S3 bucket ([#1761](https://github.com/heroku/heroku-buildpack-ruby/pull/1761))
+- Warn when app has a `bin/bundle` binstub that can cause bundler version issues ([#1728](https://github.com/heroku/heroku-buildpack-ruby/pull/1728))
+
+## [v361] - 2026-06-11
+
+- JRuby 10.0.6.0 is now available
+
+
+## [v360] - 2026-06-08
+
+- JRuby 9.4.15.0 is now available
+
+
+## [v359] - 2026-05-29
+
+
+## [v359] - 2026-05-20
+
+- Ruby 4.0.5 is now available
+
+
+## [v358] - 2026-05-18
+
+- Changed curl calls from `--silent` to `--no-progress-meter`. Using `curl -s` without `--show-error` silently swallows error messages when downloads fail, making failures hard to debug. Replace with `--no-progress-meter` which hides only the progress bar while still showing error messages and retry backoff status.
+
+## [v357] - 2026-04-21
+
+- Ruby 4.0.3 and JRuby 10.1.0.0 is now available
+
+
+## [v356] - 2026-04-08
+
+- JRuby 10.0.5.0 is now available
+
+
+## [v355] - 2026-03-27
+
+- Ruby 3.2.11 is now available
+
+
+## [v354] - 2026-03-26
+
+- Ruby 3.3.11 is now available
+
+
+## [v353] - 2026-03-25
+
+- Add heroku-26 stack support
+
+## [v352] - 2026-03-16
+
+- Ruby 4.0.2 is now available
+
+
+## [v351] - 2026-03-11
+
+- Ruby 3.4.9 is now available
+
+
+## [v349] - 2026-03-06
+
+- JRuby 10.0.4.0 is now available
+
+
+## [v348] - 2026-03-02
+
+- Changed the S3 URLs used for downloads to use AWS' dual-stack (IPv6 compatible) endpoint. ([#1717](https://github.com/heroku/heroku-buildpack-ruby/pull/1717))
+- Fix bug where an invalid DATABASE_URL is set when the adapter is not known (https://github.com/heroku/heroku-buildpack-ruby/pull/1715).
+
+## [v347] - 2026-02-02
+
+- JRuby 10.0.3.0 is now available
+
+## [v346] - 2026-02-02
+
+- Add metric: Track apps with and without `BUNDLED WITH` in the `Gemfile.lock`
+- Default bundler version changed from `2.3.25` to `2.5.23`. Ruby's [standard version of bundler](https://stdgems.org/bundler/) will take precedence if it is greater than Heroku's installed version. When there is no `BUNDLED WITH` in the `Gemfile.lock`, then `bundle install` will use the highest version of Bundler available.
+
+## [v345] - 2026-01-26
+
+- Set `WEB_CONCURRENCY_SET_BY=heroku/ruby` if `WEB_CONCURRENCY` gets set in (deprecated) `SENSIBLE_DEFAULTS` mode (https://github.com/heroku/heroku-buildpack-ruby/pull/1700)
+- Default Node.js version now 24.13.0 (https://github.com/heroku/heroku-buildpack-ruby/pull/1704)
+- Fix yarn and nodejs version change warnings (https://github.com/heroku/heroku-buildpack-ruby/pull/1699)
+
+## [v344] - 2026-01-14
+
+- Ruby 3.2.10 is now available
+
+
+## [v343] - 2026-01-13
+
+- Ruby 4.0.1 is now available
+
+## [v342] - 2026-01-09
+
+- Update bundler version warning output (https://github.com/heroku/heroku-buildpack-ruby/pull/1697)
+
+## [v341] - 2026-01-09
+
+- Bundler version installed now directly matches the value in `BUNDLED WITH` from the `Gemfile.lock`
+  Previously, this value was converted to a "known good version." For example:
+
+  `BUNDLED WITH` 2.7.x installs `bundler 2.7.2`
+
+  Now, the exact version from the `Gemfile.lock` is installed instead. Applications without
+  a `BUNDLED WITH` value will receive a default bundler version. (https://github.com/heroku/heroku-buildpack-ruby/pull/1695)
+
+## [v340] - 2026-01-06
+
+- Bundler version is now installed via running `gem install bundler` previously it was pre-built
+  and downloaded directly from S3.
+
+ This change should be a refactor (no observed change in build behavior). If your app can build with `https://github.com/heroku/heroku-buildpack-ruby#v334` but not with this version, please open a
+ support ticket https://help.heroku.com/. (https://github.com/heroku/heroku-buildpack-ruby/pull/1680)
+
+## [v339] - 2026-01-05
+
+- Ruby is now installed before bundler. Previously, Bundler was used to detect the Ruby version by calling
+  `bundle platform --ruby`. Now that the Ruby version is detected directly from the  `Gemfile.lock`, the
+  order of installation can be changed such that Ruby is installed before Bundler.
+
+  This change should be a refactor (no observed change in build behavior), but involved substantial
+  internal changes. If your app can build with `https://github.com/heroku/heroku-buildpack-ruby#v335`
+  but not with this version, please open a support ticket https://help.heroku.com/. (https://github.com/heroku/heroku-buildpack-ruby/pull/1684)
+- The `PATH` order on Heroku CI relying on `bin/test` interface has changed for applications using the `heroku/ruby`
+  buildpack. It now starts with: `/app/bin:/app/vendor/bundle/bin:/app/vendor/bundle/ruby/3.3.0/bin` which matches
+  the behavior of regular `git push heroku` and customers who specify tests via `app.json`.
+  (https://github.com/heroku/heroku-buildpack-ruby/pull/1684)
+
+
+## [v338] - 2025-12-25
+
+- Ruby 4.0.0 is now available
+
+
+## [v337] - 2025-12-18
+
+- Ruby 4.0.0.preview3 is now available
+
+
+## [v336] - 2025-12-17
+
+- Ruby 3.4.8 is now available
+
+
+## [v335] - 2025-12-15
+
+- Ruby CI applications not using Rails now have `RACK_ENV=test` set (https://github.com/heroku/heroku-buildpack-ruby/pull/1683)
+
+## [v334] - 2025-12-12
+
+- Rolled back due to https://github.com/heroku/heroku-buildpack-ruby/issues/1681
+
+## [v333] - 2025-12-03
+
+- Ruby apps using bundler 4.0.x will now receive bundler 4.0.0 (https://github.com/heroku/heroku-buildpack-ruby/pull/1677)
+
+## [v332] - 2025-12-02
+
+- Ruby version is now pulled directly from `Gemfile.lock`. Previously the version was indirectly pulled
+  via shelling out to `bundle platform --ruby`, which requires that the version of Bundler must be resolved
+  and installed first. This new logic allows us to install the requested Ruby version before installing
+  bundler. (https://github.com/heroku/heroku-buildpack-ruby/pull/1665)
+
+## [v331] - 2025-12-02
+
+- Ruby apps using bundler 4.0.x will now receive bundler 4.0.0.beta2 (https://github.com/heroku/heroku-buildpack-ruby/pull/1673)
+
+## [v330] - 2025-12-02
+
+- Support `BUNDLED WITH` in `Gemfile.lock` with two spaces. This was [updated in bundler](https://github.com/ruby/rubygems/pull/9076). [#1668](https://github.com/heroku/heroku-buildpack-ruby/pull/1668)
+
+## [v329] - 2025-11-18
+
+- Fix "BUILD_DIR: unbound variable" error when deploying without a Gemfile with `heroku/ruby` buildpack [#1663](https://github.com/heroku/heroku-buildpack-ruby/pull/1663)
+
+## [v328] - 2025-11-17
+
+- Ruby 4.0.0-preview2 is now available
+
+
+## [v327] - 2025-10-24
+
+- Ruby 3.3.10 is now available
+
+
+## [v326] - 2025-10-21
+
+- Ruby apps using bundler 2.6.x will now receive bundler 2.6.9 (https://github.com/heroku/heroku-buildpack-ruby/pull/1651)
+- Ruby apps using bundler 2.7.x will now receive bundler 2.7.2 (https://github.com/heroku/heroku-buildpack-ruby/pull/1651)
+
+## [v325] - 2025-10-21
+
+- Internal refactor: Remove Cache class dependency from Metadata class (https://github.com/heroku/heroku-buildpack-ruby/pull/1649)
+- Improve message on `bin/detect` failure to include the list of files in the root directory (https://github.com/heroku/heroku-buildpack-ruby/pull/1647)
+
+## [v324] - 2025-10-09
+
+- JRuby 9.4.14.0 is now available
+
+
+## [v323] - 2025-10-08
+
+- Ruby 3.4.7 is now available
+
+
+## [v322] - 2025-09-29
+
+- Set `export PUMA_PERSISTENT_TIMEOUT=95` to match recommended router 2.0 settings for Rails applications (https://github.com/heroku/heroku-buildpack-ruby/pull/1645)
+- Warn when using Puma prior to 7.0.0 for Router 2.0 compatibility (https://github.com/heroku/heroku-buildpack-ruby/pull/1645)
+- Error when using Puma 7.0.0 to 7.0.2 (inclusive) to prevent runtime error with `PUMA_PERSISTENT_TIMEOUT` (https://github.com/heroku/heroku-buildpack-ruby/pull/1645)
+- The `config_vars` field is no longer set in `bin/release`, this feature only affected the first deploy and is redundant with `.profile.d` usage that already exists. (https://github.com/heroku/heroku-buildpack-ruby/pull/1645)
+
+## [v321] - 2025-09-16
+
+- Ruby 3.4.6 is now available
+
+
+## [v320] - 2025-09-09
+
+- Set `export PUMA_PERSISTENT_TIMEOUT=95` to match recommended router 2.0 settings for Rack applications (https://github.com/heroku/heroku-buildpack-ruby/pull/1641)
+
+## [v319] - 2025-08-27
+
+- Add bash based failure metrics reporting for `bin/report`. This allows the buildpack to distinguish beteween types of failures that occur before Ruby code in the buildpack has executed (such as when bootstrapping). (https://github.com/heroku/heroku-buildpack-ruby/pull/1635)
+
+## [v318] - 2025-08-11
+
+- Fix `heroku_buildpack_ruby_dir: unbound variable` warning (https://github.com/heroku/heroku-buildpack-ruby/pull/1632)
+
+## [v317] - 2025-08-07
+
+- JRuby 10.0.2.0 is now available
+
+
+## [v316] - 2025-08-06
+
+- Explicitly error on end-of-life (EOL) stack `heroku-20` (https://github.com/heroku/heroku-buildpack-ruby/pull/1629)
+- Default Ruby version is now 3.3.9 (https://github.com/heroku/heroku-buildpack-ruby/pull/1624)
+
+## [v315] - 2025-07-24
+
+- Ruby 3.2.9 and 3.3.9 is now available
+
+
+## [v314] - 2025-07-18
+
+- JRuby 10.0.1.0 is now available
+
+
+## [v313] - 2025-07-15
+
+- Ruby 3.4.5 is now available
+
+
+## [v312] - 2025-06-10
+
+- JRuby 9.4.13.0 is now available
+
+
+## [v311] - 2025-06-09
+
+
+- Stream `bundle list` when `bundle install` emits no gem information. This condition happens when bundler 2.4+ runs with no gem additions or deletions (https://github.com/heroku/heroku-buildpack-ruby/pull/1610)
+
+## [v310] - 2025-05-27
+
+- Introduce internal metrics for deriving Ruby version directly from the `Gemfile.lock` to avoid needing to call `bundle platform --ruby` in the future. No change in behavior is expected. (https://github.com/heroku/heroku-buildpack-ruby/pull/1603)
+
+## [v309] - 2025-05-19
+
+- Default Ruby version is now 3.3.8 (https://github.com/heroku/heroku-buildpack-ruby/pull/1595)
+
+## [v308] - 2025-05-15
+
+- Removed support for Ubuntu 20.04 (and thus Heroku-20 / `heroku/builder:20`). This includes removing support for Ruby < 3.1 and Bundler < 2.3. (https://github.com/heroku/buildpacks-ruby/pull/1591)
+
+## [v307] - 2025-05-14
+
+- Ruby 3.4.4 is now available
+
+
+## [v306] - 2025-05-08
+
+- JRuby 9.4.12.0, 9.4.12.1, 10.0.0.0, and 10.0.0.1 is now available
+
+
+## [v305] - 2025-04-28
+
+- Fix `cp --update=none` warning `heroku-22` (https://github.com/heroku/heroku-buildpack-ruby/pull/1588)
+
+## [v304] - 2025-04-28
+
+- Fix `cp --update=none` on `heroku-20` (https://github.com/heroku/heroku-buildpack-ruby/pull/1586)
+
+## [v303] - 2025-04-25
+
+- Ruby 3.5.0-preview1 is now available
+- Fix warning message about `cp -n` (https://github.com/heroku/heroku-buildpack-ruby/pull/1583)
+
+## [v302] - 2025-04-16
+
+- Ruby 3.3.8 is now available
+
+
+## [v301] - 2025-04-14
+
+- Observe `.ruby-version` formats (https://github.com/heroku/heroku-buildpack-ruby/pull/1576)
+
+## [v300] - 2025-04-14
+
+- Ruby 3.4.3 is now available
+
+
+## [v299] - 2025-04-07
+
+
+## [v298] - 2025-04-03
+
+- Added observability metrics (https://github.com/heroku/heroku-buildpack-ruby/pull/1569)
+
+## [v297] - 2025-03-26
+
+- Ruby 3.1.7 and 3.2.8 is now available
+
+## [v296] - 2025-03-21
+
+- Bundler `1.x` usage error is downgraded to a warning. This warning will be moved to an error once `heroku-20` is Sunset (https://github.com/heroku/heroku-buildpack-ruby/pull/1565)
+
+## [v295] - 2025-03-20
+
+- Explicit error message raised with upgrade instructions for applications specifying bundler `1.x` in the Gemfile.lock (https://github.com/heroku/heroku-buildpack-ruby/pull/1561)
+
+## [v294] - 2025-03-19
+
+- Default Ruby version is now 3.3.7 (https://github.com/heroku/heroku-buildpack-ruby/pull/1534)
+- Default bundler version (when no version present in the `Gemfile.lock`) is now bundler `2.3.x` which is currently `2.3.25` (https://github.com/heroku/heroku-buildpack-ruby/pull/1534)
+- Bundler 1.x will no longer work with the Ruby buildpack (https://github.com/heroku/heroku-buildpack-ruby/pull/1534)
+
+## [v293] - 2025-02-15
+
+- Ruby 3.4.2 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1548)
+
+## [v292] - 2025-02-10
+
+- Ruby 3.2.7 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1545)
+
+
+## [v291] - 2025-01-30
+
+- JRuby 9.4.11.0 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1542)
+
+## [v290] - 2025-01-23
+
+- JRuby 9.4.10.0 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1540)
+
+## [v289] - 2025-01-17
+
+- Ruby 3.3.7 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1538)
+
+## [v288] - 2025-01-06
+
+- Ruby apps using bundler 2.6+ will now receive bundler 2.6.2 (https://github.com/heroku/heroku-buildpack-ruby/pull/1535)
+- Ruby apps using bundler 2.5.x will now receive bundler 2.5.23 (https://github.com/heroku/heroku-buildpack-ruby/pull/1535)
+
+## [v287] - 2024-12-25
+
+- Ruby 3.4.0 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1531)
+- Ruby 3.4.1 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1531)
+
+## [v286] - 2024-12-13
+
+- Ruby 3.4.0-rc1 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1528)
+
+## [v285] - 2024-11-21
+
+- Default `UV_USE_IO_URING=0` due to build timeouts [context](https://github.com/heroku/heroku-buildpack-nodejs/pull/1347) (https://github.com/heroku/heroku-buildpack-ruby/pull/1523)
+
+## [v284] - 2024-11-15
+
+- Default Node.js version now 22.11.0 (https://github.com/heroku/heroku-buildpack-ruby/pull/1503)
+- Default Yarn version now 1.22.22 (https://github.com/heroku/heroku-buildpack-ruby/pull/1503)
+
+## [v283] - 2024-11-14
+
+- No customer facing changes
+
+## [v282] - 2024-11-08
+
+- [Rolled back] Default Node.js version now 22.11.0 (https://github.com/heroku/heroku-buildpack-ruby/pull/1503)
+- [Rolled back] Default Yarn version now 1.22.22 (https://github.com/heroku/heroku-buildpack-ruby/pull/1503)
+
+## [v281] - 2024-11-07
+
+- Support Node.js on ARM builds (https://github.com/heroku/heroku-buildpack-ruby/pull/1499)
+- Add detection support for Rails 8 (https://github.com/heroku/heroku-buildpack-ruby/pull/1498)
+- Ruby 3.2.6 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1504)
+- JRuby 9.4.9.0 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1506)
+- Ruby 3.3.6 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1511)
+
+## [v280] - 2024-10-08
+
+- Ruby 3.4.0-preview2 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1496)
+
+## [v279] - 2024-09-04
+
+- Ruby 3.3.5 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1491)
+
+## [v278] - 2024-08-05
+
+- Ruby 3.2.5 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1488)
+
+## [v277] - 2024-07-11
+
+- Stop bundling bootstrap Ruby for each stack inside the buildpack archive on the buildpack registry (https://github.com/heroku/heroku-buildpack-ruby/pull/1481)
+
+## [v276] - 2024-07-09
+
+- Ruby 3.3.4 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1482)
+
+## [v275] - 2024-07-03
+
+- JRuby 9.4.8.0 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1479)
+
+## [v274] - 2024-06-28
+
+- JRuby 9.3.15.0 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1476)
+
+## [v273] - 2024-06-26
+
+- Native Gemfile.lock support for Windows Ruby users with Bundler 2.2+ (https://github.com/heroku/heroku-buildpack-ruby/pull/1469)
+
+## [v272] - 2024-06-13
+
+- Remove experimental CNB support. For official CNB support use [heroku/buildpacks-ruby](https://github.com/heroku/buildpacks-ruby) instead. (https://github.com/heroku/heroku-buildpack-ruby/pull/1464)
+- Default Ruby version is now 3.1.6 (https://github.com/heroku/heroku-buildpack-ruby/pull/1466)
+- Ruby 3.3.3 is now available
+
+## [v271] - 2024-06-03
+
+- Ruby 3.4.0-preview1 is now available
+- Ruby 3.1.6 and 3.3.2 are now available
+- JRuby 9.4.7.0, 9.4.6.0, and 9.3.14.0 are now available
+- Fix issue with sprockets reference being nil when
+  propshaft gem is used instead (https://github.com/heroku/heroku-buildpack-ruby/pull/1452)
+
+## [v270] - 2024-04-23
+
+- Ruby versions 3.0.7, 3.1.5, 3.2.4, and 3.3.1 are now available on Heroku (https://github.com/heroku/heroku-buildpack-ruby/pull/1449)
+
+## [v269] - 2024-04-23
+
+- Fix Heroku-24 Ruby buildpack bootstrapping logic (https://github.com/heroku/heroku-buildpack-ruby/pull/1446)
+- Deprecate CNB support in this buildpack; CNB support for Ruby is provided by [heroku/buildpacks-ruby](https://github.com/heroku/buildpacks-ruby) instead (https://github.com/heroku/heroku-buildpack-ruby/pull/1445)
+
+## [v268] - 2024-04-17
+
+- Heroku-24 stack initial support. Includes multi-architecture (arm64/amd64) logic that has not been tested on the platform (https://github.com/heroku/heroku-buildpack-ruby/pull/1439)
+- Remove unused Rubinius and Ruby 1.9.2 codepaths (https://github.com/heroku/heroku-buildpack-ruby/pull/1440)
+
+## [v267] - 2024-02-28
+
+- Bundler version installation is now based on both major and minor version (https://github.com/heroku/heroku-buildpack-ruby/pull/1428)
+- Applications using bundler 2.4+ must now specify a ruby version in the Gemfile.lock or they will receive the default Ruby version (https://github.com/heroku/heroku-buildpack-ruby/pull/1428)
+
+## [v266] - 2024-02-20
+
+- Officially deprecate SENSIBLE_DEFAULTS environment variable (https://github.com/heroku/heroku-buildpack-ruby/pull/1420)
+
+## [v265] - 2024-01-22
+
+- Ruby 3.2.3 is now available
+
+## [v264] - 2023-12-25
+
+- Ruby 3.3.0 is now available
+
+## [v263] - 2023-12-11
+
+- Ruby 3.3.0-rc1 is now available (https://github.com/heroku/heroku-buildpack-ruby/pull/1411)
+- Fix BUILDPACK_VENDOR_URL support (https://github.com/heroku/heroku-buildpack-ruby/pull/1406)
+
+## [v262] - 2023-11-08
+
+- Warn when relying on default Node.js or Yarn versions (https://github.com/heroku/heroku-buildpack-ruby/pull/1401)
+- Warn when default Node.js or Yarn versions change (https://github.com/heroku/heroku-buildpack-ruby/pull/1401)
+
+## [v261] - 2023-11-02
+
+- JRuby 9.4.5.0 is now available
+- JRuby 9.3.13.0 is now available
+- Default Node.js version now 20.9.0
+
+## [v260] - 2023-10-23
+
+- JRuby 9.4.4.0 is now available
+
+## [v259] - 2023-10-02
+
+- Ruby 3.3.0-preview2 is now available
+
+## [v258] - 2023-09-26
+
+- No changes
+
+## [v257] - 2023-09-20
+
+- JRuby 9.3.11.0 is now available
+
+## [v256] - 2023-08-04
+
+- Fix Ruby 2.5.7 download on Heroku-20
+
+## [v255] - 2023-07-24
+
+- JRuby 9.4.3.0 is now available
+- JRuby 9.4.2.0 is now available
+
+## [v254] - 2023-05-12
+
+- Default Ruby version is now 3.1.4
+- Ruby 3.3.0-preview1 is now available
+
+## [v253] - 2023-03-31
+
+- Ruby versions 2.7.8, 3.0.6, 3.1.4, 3.2.2 are now available
+
+## [v252] - 2023-02-08
+
+* Ruby 3.2.1 is now available
+* JRuby 9.4.1.0 is now available
+
+## [v251] - 2023-02-03
+
+* Jruby 9.3.10.0 is available
+
+## [v250] - 2022-12-25
+
+* Ruby 3.2.0 is available
+
+## [v249] - 2022-12-16
+
+* Apps with the environment variable `HEROKU_SKIP_DATABASE_PROVISION=1` set will no longer receive a database on the first push to a new Heroku app. This environment variable interface is not standard across other buildpacks and may be deprecated via warnings in the build output and changed in the future.
+
+## [v248] - 2022-12-06
+
+* Ruby 3.2.0-rc1 is available
+
+## [v247] - 2022-12-01
+
+* JRuby 9.3.7.0, 9.3.8.0, 9.3.9.0, 9.4.0.0
+
+## [v246] - 2022-11-29
+
+* Default Node.js version now 16.18.1 (https://github.com/heroku/heroku-buildpack-ruby/pull/1342)
+* Default Yarn version now 1.22.19 (https://github.com/heroku/heroku-buildpack-ruby/pull/1342)
+
+## [v245] - 2022-11-16
+
+* Bump Bundler 2 wrapper to 2.3.25 (https://github.com/heroku/heroku-buildpack-ruby/pull/1337)
+
+## [v244] - 2022-07-25
+
+* Default Ruby version is now 3.1.2 (https://github.com/heroku/heroku-buildpack-ruby/pull/1316)
+
+## [v243] - 2022-06-14
+
+* Switch away from deprecated path-based S3 URLs (https://github.com/heroku/heroku-buildpack-ruby/pull/1311)
+* Adjust curl retry and connection timeout handling (https://github.com/heroku/heroku-buildpack-ruby/pull/1312)
+
+## [v242] - 2022-06-07
+
+* Ensure `bin/release` exits zero if `tmp/heroku-buildpack-release-step.yml` does not exist (https://github.com/heroku/heroku-buildpack-ruby/pull/1309)
+* Bootstrap Ruby version used by the buildpack internals is updated to Ruby 3.1.2 (https://github.com/heroku/heroku-buildpack-ruby/pull/1310)
+
+## [v241] - 2022-06-06
+
+* `bin/release` is re-written in bash, so it supports Heroku-22 (https://github.com/heroku/heroku-buildpack-ruby/pull/1308)
+* Download presence check now includes heroku-22 (https://github.com/heroku/heroku-buildpack-ruby/pull/1290)
+
+## [v240] - 2022-04-05
+
+* Add initial support for heroku-22 (https://github.com/heroku/heroku-buildpack-ruby/pull/1289)
+* Bundler 2.x is now 2.3.10 (https://github.com/heroku/heroku-buildpack-ruby/pull/1296)
+
+## [v239] - 2022-03-02
+
+* Rollback bundler 2.x change. Bundler 2.x is now back at 2.2.33 (https://github.com/heroku/heroku-buildpack-ruby/pull/1281)
+
+## [v238] - 2022-03-02
+
+* Bundler 2.x is now 2.3.7 (https://github.com/heroku/heroku-buildpack-ruby/pull/1276)
+
+## [v237] - 2022-02-24
+
+* Default Ruby version is now 3.0.3 (https://github.com/heroku/heroku-buildpack-ruby/pull/1270)
+
+## [v236] - 2022-01-04
+
+* Fix deprecated rake tasks for Rails 7 on Heroku CI (https://github.com/heroku/heroku-buildpack-ruby/pull/1257)
+
+## [v235] - 2022-01-03
+
+* Bundler 2.x is now 2.2.33 (https://github.com/heroku/heroku-buildpack-ruby/pull/1248)
+
+## [v234] - 2021-12-16
+
+* Fix YML indentation from v233 (https://github.com/heroku/heroku-buildpack-ruby/pull/1252)
+
+## [v233] - 2021-12-16
+
+* Default node version now 16.13.1, yarn is 1.22.17 (https://github.com/heroku/heroku-buildpack-ruby/pull/1238)
+* Default Ruby version is now 2.7.5 (https://github.com/heroku/heroku-buildpack-ruby/pull/1237)
+* Remove instrumentation and LPXC logic (https://github.com/heroku/heroku-buildpack-ruby/pull/1229)
+
+## [v232] - 2021-11-09
+
+* Deactivate LPXC (https://github.com/heroku/heroku-buildpack-ruby/pull/1228)
+
+## [v231] - 2021-10-27
+
+* Applications with `package.json` now get `nodejs` installed (https://github.com/heroku/heroku-buildpack-ruby/pull/1212)
+* Applications with `yarn.lock` now get `yarn` installed (https://github.com/heroku/heroku-buildpack-ruby/pull/1212)
+
+## [v230] - 2021-10-05
+
+* Default Ruby version is now 2.7.4 (https://github.com/heroku/heroku-buildpack-ruby/pull/1193)
+
+## [v229] - 2021-08-30
+
+* Fix interoperability with other Heroku buildpacks' `$WEB_CONCURRENCY` handling (https://github.com/heroku/heroku-buildpack-ruby/pull/1188)
+
+## [v228] - 2021-06-24
+
+* Bundler 2.x is now 2.2.21 (https://github.com/heroku/heroku-buildpack-ruby/pull/1170)
+* Remove support for the Cedar-14 and Heroku-16 stacks (https://github.com/heroku/heroku-buildpack-ruby/pull/1163)
+
+## [v227] - 2021-04-19
+
+* Bundler 2.x is now 2.2.16 (https://github.com/heroku/heroku-buildpack-ruby/pull/1150)
+
+## [v226] - 2021-04-13
+
+* Bundler 2.x is now 2.2.15 (https://github.com/heroku/heroku-buildpack-ruby/pull/1144)
+
+## [v225] - 2021-02-25
+
+* Bundler 2.x is now 2.2.11 (https://github.com/heroku/heroku-buildpack-ruby/pull/1132)
+
+## [v224] - 2021-02-24
+
+* Ruby buildpack now relies on the JVM buildpack to install java for Jruby apps (https://github.com/heroku/heroku-buildpack-ruby/pull/1119)
+
+## [v223] - 2021-01-22
+
+* Fix Gemfile.lock read bug from preventing proper removal of BUNDLED WITH declaration (https://github.com/heroku/heroku-buildpack-ruby/pull/1108)
+* Fail detection with a CNB-friendly exit code (https://github.com/heroku/heroku-buildpack-ruby/pull/1111)
+
+## [v222] - 2020-11-02
+
+* CNB support for Heroku-20 (https://github.com/heroku/heroku-buildpack-ruby/pull/1096)
+
+## [v221] - 2020-10-22
+
+* Remove excessive Active Storage warnings (https://github.com/heroku/heroku-buildpack-ruby/pull/1087)
+* Add Heroku-20 to the download presence check (https://github.com/heroku/heroku-buildpack-ruby/pull/1093)
+
+## [v220] - 2020-08-07
+
+* BUNDLE_WITHOUT now accommodates values with single spaces (https://github.com/heroku/heroku-buildpack-ruby/pull/1083)
+
+## [v219] - 2020-08-06
+
+* Fix double installation of bundler on CI runs when no test script is specified (https://github.com/heroku/heroku-buildpack-ruby/pull/1073)
+* Bundler 2.x is now 2.1.4 (https://github.com/heroku/heroku-buildpack-ruby/pull/1052)
+* Persistent bundler config is now being set using the `BUNDLE_*` env vars (https://github.com/heroku/heroku-buildpack-ruby/pull/1039)
+* Rake task "assets:clean" will not get called if it does not exist (https://github.com/heroku/heroku-buildpack-ruby/pull/1018)
+* CNB: Fix the `gems` layer not being made accessible by subsequent buildpacks (https://github.com/heroku/heroku-buildpack-ruby/pull/1033)
+
+## [v218] - 2020-07-13
+
+* The rake binstub generated from compiling Ruby will no longer be placed in the local `bin/rake` location (https://github.com/heroku/heroku-buildpack-ruby/pull/1031)
+* A bug in 2.6.0, 2.6.1, 2.6.3 require a Ruby upgrade, a warning has been added (https://github.com/heroku/heroku-buildpack-ruby/pull/1015)
+* The spring library is now disabled by setting the environment variable DISABLE_SPRING=1 (https://github.com/heroku/heroku-buildpack-ruby/pull/1017)
+* Warn when a bad "shebang" line in a binstub is detected (https://github.com/heroku/heroku-buildpack-ruby/pull/1014)
+* Default node version now 12.16.2, yarn is 1.22.4 (https://github.com/heroku/heroku-buildpack-ruby/pull/986)
+
+ ## [v217] - 2020-07-02
+
+* Gracefully handle unrecognised stacks ([#982](https://github.com/heroku/heroku-buildpack-ruby/pull/982))
+
+## [v216] (rolled back)
+
+
+## [v215] - 2020-04-09
+
+* Fix bundler cache not being used in CI builds (https://github.com/heroku/heroku-buildpack-ruby/pull/978)
+
+## [v214] - 2020-04-02
+
+* Default Ruby version is now 2.6.6 (https://github.com/heroku/heroku-buildpack-ruby/pull/974)
+* Fix regression. PATH value for `yarn` at runtime was relative instead of absolute (https://github.com/heroku/heroku-buildpack-ruby/pull/975)
+
+## [v213] - 2020-04-01
+
+* Fix regression. PATH value for `ruby` at runtime was relative instead of absolute (https://github.com/heroku/heroku-buildpack-ruby/pull/973)
+
+## [v212] - 2020-03-26
+
+* Cloud Native Buildpack support (https://github.com/heroku/heroku-buildpack-ruby/pull/888)
+
+## [v211] - 2020-03-12
+
+* Fix issue where the wrong version of bundler is used on CI apps (https://github.com/heroku/heroku-buildpack-ruby/pull/961)
+* Remove libpq external dependency (https://github.com/heroku/heroku-buildpack-ruby/pull/959)
+
+## [v210] - 2020-03-06
+
+* Fix version download error warning inversion logic (https://github.com/heroku/heroku-buildpack-ruby/pull/958)
+
+## [v209] - 2020-03-05
+
+* Fix bug in version download error message logic (https://github.com/heroku/heroku-buildpack-ruby/pull/957)
+
+## [v208] - 2020-03-04
+
+* Improve Ruby version download error messages (https://github.com/heroku/heroku-buildpack-ruby/pull/953)
+* Update default Ruby version to 2.6.5 (https://github.com/heroku/heroku-buildpack-ruby/pull/947)
+
+## [v207] - 2019-12-16
+
+* Vendor in libpq 5.12.1 for Heroku-18 (https://github.com/heroku/heroku-buildpack-ruby/pull/936)
+* Remove possibilities of false exceptions being raised by removing `BUNDLED WITH` from the `Gemfile.lock` (https://github.com/heroku/heroku-buildpack-ruby/pull/928)
+
+## [v206] - 2019-10-15
+
+* Default Ruby version for new apps is now 2.5.7 (https://github.com/heroku/heroku-buildpack-ruby/pull/926)
+* Using old and EOL versions of Ruby now generate warnings (https://github.com/heroku/heroku-buildpack-ruby/pull/864)
+
+## [v205] - 2019-09-24
+
+* Update bundler 1.x to 1.17.3 (https://github.com/heroku/heroku-buildpack-ruby/pull/845)
+* Default `MALLOC_ARENA_MAX=2` for new applications (https://github.com/heroku/heroku-buildpack-ruby/pull/752)
+
+## [v204] - 2019-09-12
+
+* Default Ruby version for new apps is now 2.5.6 (https://github.com/heroku/heroku-buildpack-ruby/pull/919)
+* Ensure that old binstubs are removed before new ones are generated (https://github.com/heroku/heroku-buildpack-ruby/pull/914)
+* Fix windows Gemfile.lock BUNDLED WITH support (https://github.com/heroku/heroku-buildpack-ruby/pull/898)
+
+## [v203] - 2019-08-20
+
+* Make sure Rails 6 apps have a `tmp/pids` folder so they can boot (https://github.com/heroku/heroku-buildpack-ruby/pull/909)
+
+## [v202] - 2019-08-20
+
+* Add support class for Rails 6 (https://github.com/heroku/heroku-buildpack-ruby/pull/908)
+
+## [v201] - 2019-06-23
+
+* Set memory default for Node builds (https://github.com/heroku/heroku-buildpack-ruby/pull/861)
+* Default Ruby version is now 2.5.5, was previously 2.5.3 (https://github.com/heroku/heroku-buildpack-ruby/pull/863)
+* Default Node version is now 10.15.3 and default Yarn version is now 1.16.0 (https://github.com/heroku/heroku-buildpack-ruby/pull/884)
+* Bundler 2 now uses 2.0.2 (https://github.com/heroku/heroku-buildpack-ruby/pull/894)
+
+## [v200] - 2019-03-07
+
+* Fix: Environment variables not being exported for other buildpacks in CI (https://github.com/heroku/heroku-buildpack-ruby/pull/858)
+* Ignore invalid byte encodings when detecting rails config (https://github.com/heroku/heroku-buildpack-ruby/pull/854)
+
+## v199 - 2019-02-19
+
+* Add support for arbitrary Bundler major versions, most notably bundler 2 (https://github.com/heroku/heroku-buildpack-ruby/pull/850)
+
+## v198 - 2019-01-17
+
+* Rev-default Ruby version to be the latest patch release of last years Ruby version 2.5.3 (https://github.com/heroku/heroku-buildpack-ruby/pull/846)
+* Allow apps to enable `RUBYOPT=--jit` (https://github.com/heroku/heroku-buildpack-ruby/pull/848)
+
+## v197 - 2018-12-18
+
+* Upgrade node version (https://github.com/heroku/heroku-buildpack-ruby/pull/831)
+* Upgrade yarn version (https://github.com/heroku/heroku-buildpack-ruby/pull/832)
+
+## v196 - 2018-10-31
+
+* Delete the sprockets temp directory for a smaller runtime slug if they are not building assets at runtime (https://github.com/heroku/heroku-buildpack-ruby/pull/812)
+
+## v195 - 2018-10-18
+
+* Default Ruby version is now 2.4.5 (https://github.com/heroku/heroku-buildpack-ruby/pull/821)
+
+## v194 - 2018-10-16
+
+* Do not add the `jobs:work` command if an app does not have that rake task available (https://github.com/heroku/heroku-buildpack-ruby/pull/810)
+
+## v193 - 2018-09-14
+
+* Fix link (https://github.com/heroku/heroku-buildpack-ruby/pull/811)
+
+## v192 - 2018-09-14
+
+* Add error messages when using unsupported Ruby versions on the Heroku-18 stack (https://github.com/heroku/heroku-buildpack-ruby/pull/809)
+
+## v191 - 2018-08-23
+
+* Warn when `config.action_dispatch.x_sendfile_header` is set but apache and nginx are not being used (https://github.com/heroku/heroku-buildpack-ruby/pull/795)
+
+## v190 - 2018-07-24
+
+* Support TAP output for Heroku CI (https://github.com/heroku/heroku-buildpack-ruby/pull/790).
+
+## v189 - 2018-07-10
+
+* Colorize build failures and warnings. (https://github.com/heroku/heroku-buildpack-ruby/pull/788)
+
+## v188 - 2018-06-26
+
+* Fix rails config detect timeout. Addresses the process deadlock when detecting rails config that contains an infinite task. This was originally addressed in #770 but the implementation did not handle all cases. (#781)
+
+## v187 - 2018-06-19
+
+* Prevent apps from deploying with known security vulnerability activated via config (#776)
+
+## v186 - 2018-06-12
+
+* The Ruby buildpack can now detect Rails configuration in a project (#758 #770)
+
+## v185 - 2018-05-31
+
+* The Ruby buildpack bootstrap Ruby version is now 2.5.1. This is not a customer facing feature (#765)
+
+## v184 - 2018-05-30
+
+* Default Ruby version is now 2.4.4 (#734)
+
+## v183 - 2018-04-26
+
+* Support for not yet released heroku-18 stack (#750)
+
+## v182 - 2018-04-24
+
+* Do not warn when `rails runner` cannot be executed (#749)
+
+## v181 - 2018-04-23
+
+* The `active_storage` is not guaranteed to be present (#748)
+
+## v180 - 2018-04-23
+
+* Fix case where user environment variables were not being used (#745)
+
+## v179 - 2018-04-23
+
+* Emit warnings for Active Storage (#739)
+
+## v178 - 2018-04-17
+
+* Use S3 directly instead of s3pository for Node downloads (#740)
+
+## v177 - 2018-04-10
+
+* New apps that do not specify a Ruby version now get 2.3.7 (#732)
+* Bugfix: `bundle install` output no longer has an extra newline (#735)
+* Bugfix: when deploying an application the `ruby` version specified in the Gemfile is available outside of the home directory (#733)
+
+## v176 - 2018-03-27
+
+* Node version upgraded to v8.9.4 (#714)
+* Yarn version upgraded to v1.5.1 (#714)
+* Fix issue with malformed UTF-8 string parsing (#724)
+
+## v175 - 2018-03-21
+
+* Suggest users encountering a specific sprockets error in specific beta versions to upgrade (#718)
+* Log metrics for common failures (#716)
+
+## v174 - 2018-02-13
+
+* Only set JAVA_HOME for Bundler when using JRuby (#649, @jkutner)
+
+## v173 - 2017-12-22
+
+* Remove Bundler shim since Bundler 2.5.0 will not vendor Bundler (#645)
+
+## v172 - 2017-12-22
+
+* updated Ruby 2.5.0 support + Bundler shim (#640)
+* Disable bundler version check (#632)
+* set JAVA_HOME to absolute path during `bundle install` (#631)
+
+## v170 - 2017-10-19
+
+* Compatibility for Ruby 2.5.0 preview 1 (#628)
+
+## v169 - 2017-09-28
+
+* Yarn version upgraded to v1.0.2
+
+## v168 - 2017-08-14
+
+* Install Node when using either ExecJS _or_ Webpacker (#608)
+* Make installs more robust against temporary network issues by retrying failed
+  downloads in `LanguagePack::Fetcher#fetch_untar`, which installs Rubies (#585)
+
+## v167 - 2016-07-25
+
+* Update Bundler to 1.15.2 (#602)
+
+## v166 - 2017-07-11
+
+* no changes from v165
+
+## v165 - 2017-07-11
+
+* Set `$JAVA_HOME` for JRuby apps during build (#593)
+* Update Node to 6.11.1 (#598)
+
+## v164 - 2017-06-21
+
+* Update Bundler to 1.15.1 (#579)
+
+## v163 - 2017-05-22
+
+* Fix CI rake tasks not running (#571)
+
+## v162 - 2017-05-18
+
+* Disable RuboCop warnings for `heroku_clear_tasks` (#567)
+
+## v161 - 2017-05-18
+
+* Ruby apps being run on CI are no longer expected to have Rails commands (#565)
+
+## v160 - 2017-05-18
+
+* `bin/rails test` only gets called in CI for Rails 5+ apps
+* support `:sql` (structure) Rails schema for CI (#549)
+
+## v159 - 2017-04-24
+
+*  Blacklist JAVA_OPTS and JAVA_TOOL_OPTIONS during build (#559)
+
+## v158 - 2017-04-12
+
+*  Fix CI issue causing system Ruby to be used (#558)
+
+## v157 - 2017-04-11
+
+* Fix "double ruby rainbow bug" caused by executing two `compile` actions on the same
+app (#553 & #555)
+* Remove Ruby 1.8.7 compatibility to allow for #555. This version of Ruby has been EOL
+for a long time. It is not available on Cedar-14 and Cedar-10 is EOL
+
+## v156 - 2017-04-11
+
+* Update default Ruby version to 2.3.4.
+
+## v155 - 2017-03-16
+
+* Yarn now installed for apps with `webpacker` gem (#547)
+
+## v154 - 2017-03-01
+
+* Postgres database add-on will only be provisioned if app has a postgres driver in the `Gemfile`. (#535)
+* Fix regression, where JRuby patchlevel was being pulled from `Gemfile.lock` and used when not appropriate (#536)
+
+## v153 - 2017-01-18
+
+* Fix regression, where defaults would override user env with rake (#528)
+
+## v152 - 2017-01-18
+
+* Remove RAILS_GROUPS=assets from being set in .profile.d (#526)
+
+## v151 - 2017-01-16
+
+* Upgrade to bundler 1.13.7 (#519)
+* Vendor Default Ruby to execute the buildpack (#515)
+* Heroku CI Support (#516)
+
+## v150 - 2016-12-23
+
+* Allow deployment of pre-release rubies (preview and rc) with Bundler 1.13.6+. This is needed because the patch level is recorded in the gemfile as `-1` since it is not released yet. For example 2.4.0rc1 will show up in a `Gemfile.lock` like this:
+
+```
+RUBY VERSION
+   ruby 2.4.0p-1
+```
+
+## v149 - 2016-12-01
+
+* Guarantee we always show warning when upgrading bundler version.
+
+## v148 - 2016-11-17
+
+* Default Ruby Version is 2.2.6
+* Update libyaml to 0.1.7 for [CVE-2014-9130](https://devcenter.heroku.com/changelog-items/1016)
+
+## v147 - 2016-11-15
+
+* Bump bundler to 1.13.6 [Bundler changelog](https://github.com/bundler/bundler/blob/v1.13.6/CHANGELOG.md). Allows for use of Ruby version operators.
+
+## v146 - 2016-03-23
+
+* Warn when `.bundle/config` is checked in (#471)
+* Do not cache `.bundle/config` between builds (#471)
+* Set WEB_CONCURRENCY for M-Performance dynos using sensible defaults (#474)
+* Fix rake task detection in Rails apps actually fails builds (#475)
+
+## v145 - 2016-03-08
+
+* Bump bundler to 1.11.2 [Bundler changelog](https://github.com/bundler/bundler/blob/master/CHANGELOG.md#1112-2015-12-15) (#461)
+* Rails 5 Support for logging to STDOUT via environment variable (#460)
+* Fail build when rake tasks cannot be detected in a Rails app (#462)
+
+## v144 - 2016-02-01
+
+* Fix default ruby to actually be Ruby 2.2.4 (#456)
+
+## v143 - 2016-01-28
+
+* Change default for new apps to Ruby 2.2.4 (#454)
+
+## v142 - 2016-01-14
+
+* Added pgconfig jar to JDK for JRuby JDBC (#450)
+* Let API pick exact postgres plan (#449)
+* Follow redirects on `curl` command (#443)
+* Check for preinstalled JDK (#434)
+
+## v141 - 2015-11-03
+
+* Support for custom JDK versions in system.properties (#423)
+* Fix nodejs buildpack integration (#429)
+* Automatic jruby heap setting for IX dynos (#426)
+* Warn when RAILS_ENV != production (https://devcenter.heroku.com/articles/deploying-to-a-custom-rails-environment)
+* Warn when using asset_sync (https://devcenter.heroku.com/articles/please-do-not-use-asset-sync)
+
+## v140 - 2015-09-09
+
+* JRuby specific ruby error message (#412)
+
+## v139 - 2015-08-31
+
+* Cached asset file should never take precedent over existing file (#402)
+* Do not write `database.yml` when using active record >= 4.1 (previously we only detected >= Rails 4.1) (#403)
+
+## v138 - 2015-05-19
+
+* Bump bundler to 1.9.7 [Bundler changelog](https://github.com/bundler/bundler/blob/master/CHANGELOG.md#196-2015-05-02) (#378)
+
+## v137 - 2015-05-11
+
+* Blacklist `JRUBY_OPTS`, use `JRUBY_BUILD_OPTS` to override build `JRUBY_OPTS`.  (#384)
+* Revert `--dev` during JRuby build for now. (#384)
+
+## v136 - 2015-05-06
+
+* JRUBY_BUILD_OPTS env var will override any build time jruby opts (#381)
+
+## v135 - 2015-05-05
+
+* Support sprockets 3.0 manifest file naming convention (#367)
+* Set `--dev` by default for JRuby builds (but not at runtime). This optimizes the JVM for short process and is ideal for `bundle install` and asset precompiles.
+* Cleanup `.git` folders in the bundle directory after `bundle install`.
+
+## v134 - 2015-03-01
+
+* JVM is now available on cedar-14, do not vendor in JVM based on individual gems. If customer needs a specific version they should use multibuildpack with java and ruby buildpacks.
+* Set a default value of WEB_CONCURRENCY based on dyno size when `SENSIBLE_DEFAULTS` environment variable is present.
+* Run `bundle clean` in the same context as `bundle install` heroku/heroku-buildpack-ruby#347
+* Rails 4.2+ apps will have environment variable RAILS_SERVE_STATIC_FILES set to "enabled" by default #349
+* Rails 5 apps now work on Heroku #349
+
+## v133 - 2015-01-22
+
+* Bump bundler to 1.7.12 which includes multiple fixes and support for block source declaration (https://github.com/bundler/bundler/blob/1-7-stable/CHANGELOG.md).
+
+## v132 - 2015-01-21
+
+* Support multibuildpack export file (#319)
+* Auto set the JVM MAX HEAP based on dyno size for JRuby (#323)
+* Use s3 based npmjs servers for node (#336)
+* Support system.properties file for specifying JDK in JRuby (#305)
+* Fix ruby version parsing to support JRuby 9.0.0.0.pre1 (#339)
+
+## v131 - 2015-01-15
+
+* Revert v130 due to lack of proper messaging around WEB_CONCURRENCY settings.
+
+## v130 - 2015-01-15
+
+* Auto set WEB_CONCURRENCY based on dyno size if not already set.
+* Support multibuildpack export file (#319)
+* Auto set the JVM MAX HEAP based on dyno size for JRuby (#323)
+* Use s3 based npmjs servers for node (#336)
+* Support system.properties file for specifying JDK in JRuby (#305)
+
+## v129 - 2014-11-06
+
+* Fix asset caching bug (#300)
+
+## v128 - 2014-11-04
+
+* Better cedar14 Ruby install error message
+
+## v127 - 2014-09-18
+
+* rbx is now stack aware
+
+## v126 - 2014-08-04
+
+* fix bundler cache clearing on ruby version change
+* vendor the jvm when yui-compressor is detected
+
+## v125 - 2014-08-01
+
+* bump to node 0.10.30 on cedar-14
+
+## v124 - 2014-08-01
+
+* use node 0.10.29 on cedar-14
+* properly use vendored jvm, so not to be dependent on java on the stack image
+
+## v123 - 2014-07-25
+
+* fix permission denied edge cases when copying the bundler cache with minitest
+
+## v122 - 2014-07-25
+
+* handle bundler cache for stack changes on existing apps
+
+## v121 - 2014-06-30
+
+* on new apps, source default envs instead of replacing them
+* support different stacks for new apps
+
+## v120 - 2014-06-16
+
+* Bump bundler to 1.6.3 which includes improved dependency resolver
+
+## v119 - 2014-05-09
+
+* Temporarily disable default ruby cache
+
+## v118 - 2014-05-06
+
+* Ruby version detection now loads user environment variables
+
+## v117 - 2014-04-14
+
+Features:
+
+
+Bugfixes:
+
+* fix anvil use case of multibuildpack with node
+
+
+## v116 - 2014-04-10
+
+Features:
+
+
+Bugfixes:
+
+* Revert back to Bundler 1.5.2
+
+
+## v115 - 2014-04-09
+
+Features:
+
+
+Bugfixes:
+
+* Add default process types to all apps deployed regardless of `Procfile`
+
+## v114 - 2014-04-09
+
+Features:
+
+* Bundler 1.6.1
+* Warn when not using a Procfile (looking at you webrick)
+
+Bugfixes:
+
+
+## v113 - 2014-04-08
+
+Features:
+
+* use heroku-buildpack-nodejs's node binary
+* `CURL_CONNECT_TIMEOUT` and `CURL_TIMEOUT` are configurable as ENV vars
+
+Bugfixes:
+
+* Don't double print "Running: rake assets:precompile" on Ruby apps
+
+
+## v112 - 2014-03-27
+
+Features:
+
+
+Bugfixes:
+
+* compile psych with libyaml 0.1.6 for CVE-2014-2525
+
+## v111 - 2014-03-20
+
+Features:
+
+
+Bugfixes:
+
+* spelling
+
+
+## v110 - 2014-03-20
+
+Features:
+
+* Better message when running `assets:precompile` without a database
+
+Bugfixes:
+
+## v108 - 2014-02-27
 
 Features:
 
@@ -10,13 +1243,13 @@ Bugfixes:
 
 * don't let users step on themselves by replacing `env` in `$PATH`
 
-## v107 (2/26/2014)
+## v107 - 2014-02-26
 
 Features:
 
 Bugfixes:
 
-* more shellescaping bug fixes
+* more shell escaping bug fixes
 
 
 ## v105
@@ -24,16 +1257,16 @@ Bugfixes:
 Rollbacked to v103
 
 
-## v104 (2/26/2014)
+## v104 - 2014-02-26
 
 Features:
 
 Bugfixes:
 
-* fix bugs in shellescaping (#231)
+* fix bugs in shell escaping (#231)
 
 
-## v103 (2/18/2014)
+## v103 - 2014-02-18
 
 Features:
 
@@ -42,7 +1275,7 @@ Features:
 Bugfixes:
 
 
-## v102 (2/6/2014)
+## v102 - 2014-02-06
 
 Features:
 
@@ -51,7 +1284,7 @@ Bugfixes:
 * use blacklist of env vars, so users can't break the build process
 
 
-## v101 (2/5/2014)
+## v101 - 2014-02-05
 
 Features:
 
@@ -62,7 +1295,7 @@ Bugfixes:
 * quote ponies env vars, so build doesn't break
 
 
-## v100 (2/4/2014)
+## v100 - 2014-02-04
 
 Features:
 
@@ -70,7 +1303,7 @@ Bugfixes:
 
 * compile psych with libyaml 0.1.5 for CVE-2013-6393
 
-## v99 (2/4/2014)
+## v99 - 2014-02-04
 
 Features:
 
@@ -79,7 +1312,7 @@ Features:
 Bugfixes:
 
 
-## v98 (1/30/2014)
+## v98 - 2014-01-30
 
 Features:
 
@@ -88,7 +1321,7 @@ Bugfixes:
 * Use vendored JDK binary during build
 
 
-## v97 (1/30/2014)
+## v97 - 2014-01-30
 
 Features:
 
@@ -97,7 +1330,7 @@ Bugfixes:
 * Actually finalize method rename to `install_bundler_in_app`
 
 
-## v96 (1/29/2014)
+## v96 - 2014-01-29
 
 Features:
 
@@ -109,7 +1342,7 @@ Bugfixes:
 
 Rollback to v93
 
-## v94 (1/29/2014)
+## v94 - 2014-01-29
 
 Features:
 
@@ -117,7 +1350,7 @@ Bugfixes:
 
 * Fixed `uninitialized constant Rake::DSL` error when running rake tasks on Ruby 1.9.2
 
-## v93 (01/28/2014)
+## v93 - 2014-01-28
 
 Features:
 
@@ -125,7 +1358,7 @@ Features:
 
 Bugfixes:
 
-## v92 (01/27/2014)
+## v92 - 2014-01-27
 
 Features:
 
@@ -134,7 +1367,7 @@ Bugfixes:
 * Only display rake error messages if a `Rakefile` exists
 * when detecting for ruby version, don't use stderr messages
 
-## v91 (01/16/2014)
+## v91 - 2014-01-16
 
 Features:
 
@@ -143,7 +1376,7 @@ Features:
 Bugfixes:
 
 
-## v90 (01/09/2014)
+## v90 - 2014-01-09
 
 Features:
 
@@ -151,7 +1384,7 @@ Features:
 
 Bugfixes:
 
-## v89 (01/09/2014)
+## v89 - 2014-01-09
 
 Features:
 
@@ -159,7 +1392,7 @@ Features:
 
 Bugfixes:
 
-## v86 (12/11/2013)
+## v86 - 2013-12-11
 
 Features:
 
@@ -168,7 +1401,7 @@ Bugfixes:
 * Windows warnings will now display before bundle install, this prevents an un-resolvable `Gemfile` from erroring which previously prevented the warning roll up from being shown. When this happened the developer did not see that we are clearing the `Gemfile.lock` from the git repository when bundled on a windows machine.
 * Checks for `public/assets/manifest*.json` and `public/assets/manifest.yml` will now come before Rake task detection introduced in v85.
 
-## v85 (12/05/2013)
+## v85 - 2013-12-05
 
 Features:
 
@@ -178,7 +1411,7 @@ Bugfixes:
 * Any errors in a Rakefile will now be explicitly shown as such instead of hidden in a `assets:precompile` task detection failure (#171)
 * Now using correct default "hobby" database #179
 
-## v84 (11/06/2013)
+## v84 - 2013-11-06
 
 Features:
 
@@ -189,7 +1422,7 @@ Bugfixes:
 
 * Fix default gem cache
 
-## v83 (10/29/2013)
+## v83 - 2013-10-29
 
 Features:
 
@@ -203,20 +1436,20 @@ Bugfixes:
 * Errors in Gemfiles will no longer show up as bad ruby versions #36
 * Fix warning warning libjffi-1.2.so on < JRuby 1.7.3
 
-## v82 (10/28/2013)
+## v82 - 2013-10-28
 
 Bugfixes:
 
 * Rails 3 deploys that do not successfully run `assets:precompile` will now fail.
 
-## v81 (10/15/2013)
+## v81 - 2013-10-15
 
 Features:
 
 * add Default Bundler Cache for new Ruby 2.0.0 apps
 * use Virginia S3 bucket instead of Cloudfront
 
-## v80 (9/23/2013)
+## v80 - 2013-09-23
 
 Features:
 
@@ -225,16 +1458,16 @@ Features:
 
 Bugfixes:
 
-* Disable invoke dynamic on JRuby by default until JDK stabalizes it
+* Disable invoke dynamic on JRuby by default until JDK stabilizes it
 
-## v79 (9/3/2013)
+## v79 - 2013-09-03
 
 Bugfixes:
 
 * Remove LPXC debug output when `DEBUG` env var is set (#141)
 * Symlink ruby.exe, so Rails 4 bins work for Windows (#139)
 
-## v78 (8/28/2013)
+## v78 - 2013-08-28
 
 Features:
 
@@ -244,19 +1477,19 @@ Bugfixes:
 
 * Fix issue #127 Race condition with LPXC
 
-## v77 (8/5/2013)
+## v77 - 2013-08-05
 
 Features:
 
 * Force nokogiri to compile with system libs
 
-## v76 (7/29/2013)
+## v76 - 2013-07-29
 
 Bugfixes:
 
 * fix request_id for instrumentation to follow standard
 
-## v75 (7/29/2013)
+## v75 - 2013-07-29
 
 Features:
 
@@ -267,45 +1500,45 @@ Bugfixes:
 
 * OpenJDK version was rolled back, stop special casing JRuby 1.7.3.
 
-## v74 (7/24/2013)
+## v74 - 2013-07-24
 
 Bugfixes:
 
 * Lock JRuby 1.7.3 and lower to older version of JDK due to <https://github.com/jruby/jruby/issues/626>
 
-## v73 (7/23/2013)
+## v73 - 2013-07-23
 
 * Revert to v69 due to asset:precompile bugs
 
-## v72 (7/23/2013)
+## v72 - 2013-07-23
 
 Bugfixes:
 
 * Fix rake task detection for Rails 3 (@hynkle, #118)
 
-## v71 (7/18/2013)
+## v71 - 2013-07-18
 
 * Revert to v69 due to asset:precompile bugs
 
-## v70 (7/18/2013)
+## v70 - 2013-07-18
 
 Bugfixes:
 
 * Don't silently fail rake task checks (@gabrielg, #34)
 
-## v69 (7/16/2013)
+## v69 - 2013-07-16
 
 Bugfixes:
 
 * Add spacing to end of instrumentation
 
-## v68 (7/16/2013)
+## v68 - 2013-07-16
 
 Features:
 
 * Log buildpack name and entering rails3/4 compile
 
-## v67 (7/10/2013)
+## v67 - 2013-07-10
 
 Features:
 
@@ -317,13 +1550,13 @@ Bugfixes:
 * Don't print DEBUG messages for lxpc when env var is present
 * Fix ruby gemfile warning line for JRuby
 
-## v66 (7/9/2013)
+## v66 - 2013-07-09
 
 Bugfixes:
 
 * Include logtoken properly
 
-## v65 (7/9/2013)
+## v65 - 2013-07-09
 
 Features:
 
@@ -333,7 +1566,7 @@ Bugfixes:
 
 * Fix DATABASE_URL to use jdbc-postgres for JRuby (@jkrall, #116)
 
-## v64 (6/19/2013)
+## v64 - 2013-06-19
 
 Features:
 
@@ -345,7 +1578,7 @@ Bugfixes:
 
 * fix sqlite3 error messaging detection
 
-## v63 (6/17/2013)
+## v63 - 2013-06-17
 
 Features:
 
@@ -353,14 +1586,14 @@ Features:
 * Change default ruby to 2.0.0
 * Stop using the stack image ruby and always vendor ruby
 
-## v62 (5/21/2013)
+## v62 - 2013-05-21
 
 Bugfixes:
 
 * Correctly detect asset manifest files in Rails 4
 * Fix jruby 1.8.7 bundler/psych require bug
 
-## v61 (4/18/2013)
+## v61 - 2013-04-18
 
 Features:
 
@@ -370,62 +1603,62 @@ Bugfixes:
 
 * Rebuild bundler cache if rubygems 2 is detected. Bugfixes in later rubygems.
 
-## v60 (4/17/2013)
+## v60 - 2013-04-17
 
 Security:
 
 * Disable Java RMI Remote Classloading for CVE-2013-1537, <https://bugzilla.redhat.com/show_bug.cgi?id=952387>
 
-## v59 (4/4/2013)
+## v59 - 2013-04-04
 
 Bugfixes:
 
 * Change JVM S3 bucket
 
-## v58 (3/19/2013)
+## v58 - 2013-03-19
 
 Bugfixes:
 
 * Fix ruby 1.8.7 not being able to compile native extensions
 
-## v57 (3/18/2013)
+## v57 - 2013-03-18
 
 Bugfixes:
 
 * Fix git gemspec bug in bundler
 
-## v56 (3/11/2013)
+## v56 - 2013-03-11
 
 Bugfixes:
 
 * Upgrade bundler to 1.3.2 to fix --dry-clean/Would have removed bug in bundle clean, part 2.
 
-## v55 (3/7/2013)
+## v55 - 2013-03-07
 
 Bugfixes:
 
 * Revert back to Bundler 1.3.0.pre.5, see https://gist.github.com/mattonrails/e063caf86962995e7ba0
 
-## v54 (3/7/2013)
+## v54 - 2013-03-07
 
 Bugfixes:
 
 * Upgrade bundler to 1.3.2 to fix --dry-clean/Would have removed bug in bundle clean
 
-## v53 (3/6/2013)
+## v53 - 2013-03-06
 
 Bugfixes:
 
 * bin/detect for Rails 3 and 4 will use railties for detection vs the rails gem
 * bin/detect does not error out when Gemfile + Gemfile.lock are missing
 
-## v52 (2/25/2013)
+## v52 - 2013-02-25
 
 Bugfixes:
 
 * Revert back to 1.3.0.pre.5 due to bundler warnings
 
-## v51 (2/25/2013)
+## v51 - 2013-02-25
 
 Features:
 
@@ -436,39 +1669,39 @@ Bugfixes:
 
 * Better buildpack detection through Gemfile.lock gems
 
-## v50 (1/31/2013)
+## v50 - 2013-01-31
 
 Features:
 
 * Restore ruby deploys back to normal
 
-## v49 (1/30/2013)
+## v49 - 2013-01-30
 
 Features:
 
 * Re-enable ruby deploys for apps just using the heroku cache
 * Display ruby version change when busting the cache
 
-## v48 (1/30/2013)
+## v48 - 2013-01-30
 
 Features:
 
 * Update deploy error message copy to link to status incident.
 
-## v47 (1/30/2013)
+## v47 - 2013-01-30
 
 Features:
 
 * Disable ruby deploys due to rubygems.org compromise
 
-## v46 (1/10/2013)
+## v46 - 2013-01-10
 
 Features:
 
 * Upgrade Bundler to 1.3.0.pre.5
 * bundler binstubs now go in vendor/bundle/bin
 
-## v45 (12/14/2012)
+## v45 - 2012-12-14
 
 Features:
 
@@ -476,87 +1709,87 @@ Features:
 * Enable Invoke Dynamic on JRuby by default
 * GEM_PATH is now updated on each push
 
-## v44 (12/14/2012)
+## v44 - 2012-12-14
 
 Faulty Release
 
-## v43 (12/13/2012)
+## v43 - 2012-12-13
 
 Features:
 
 * Upgrade Bundler to 1.3.0.pre.2
 
-## v42 (11/26/2012)
+## v42 - 2012-11-26
 
 Features:
 
 * Upgrade Bundler to 1.2.2 to fix Ruby 2.0.0/YAML issues
 
-## v41 (11/1/2012)
+## v41 - 2012-11-01
 
 Features:
 
 * Enable ruby 2.0.0 support for testing
 
-## v40 (10/14/2012)
+## v40 - 2012-10-14
 
 Features:
 
 * Cache version of the buildpack we used to deploy
 * Purge cache when v38 is detected
 
-## v39 (10/14/2012)
+## v39 - 2012-10-14
 
 Bugfixes:
 
 * Don't display cache clearing message for new apps
 * Actually clear bundler cache on ruby version change
 
-## v38 (10/14/2012)
+## v38 - 2012-10-14
 
 Bugfixes:
 
 * Stop bundle cache from continually growing
 
-## v37 (10/12/2012)
+## v37 - 2012-10-12
 
 Bugfixes:
 
 * Remove temporary workaround from v36.
 * Clear bundler cache upon Ruby version change
 
-## v36 (10/12/2012)
+## v36 - 2012-10-12
 
 Bugfixes:
 
 * Always clear the cache for ruby 1.9.3 as a temporary workaround due to the security upgrade
 
-## v35 (9/19/2012)
+## v35 - 2012-09-19
 
 Features:
 
 * Upgrade to Bundler 1.2.1
 * Display bundle clean output
-* More resilent to rubygems.org API outages
+* More resilient to rubygems.org API outages
 
 Bugfixes:
 
 * `bundle clean` works again
 
-## v34 (8/30/2012)
+## v34 - 2012-08-30
 
 Features:
 
 * Upgrade to Bundler 1.2.0
 
-## v33 (8/9/2012)
+## v33 - 2012-08-09
 
 Features:
 
 * Upgrade to Bundler 1.2.0.rc.2
 * vendor JDK7 for JRuby, but disable invoke dynamic
 
-## v29 (7/19/2012)
+## v29 - 2012-07-19
 
 Features:
 
@@ -564,7 +1797,7 @@ Features:
 * sync stdout so that the buildpack streams even in non-interactive shells
 * Upgrade to Bundler 1.2.0.rc
 
-## v28 (7/16/2012)
+## v28 - 2012-07-16
 
 Features:
 
@@ -575,39 +1808,39 @@ Bugfixes:
 
 * sqlite3 error gets displayed again
 
-## v27 (6/14/2012)
+## v27 - 2012-06-14
 
 Bugfixes:
 
 * Remove `vendor/bundle` message only appears when dir actually exists
 
-## v26 (6/14/2012)
+## v26 - 2012-06-14
 
 Features:
 
 * print message when assets:precompile finishes successfully
 * Remove `vendor/bundle` if user commits it to their git repo.
 
-## v25 (6/12/2012)
+## v25 - 2012-06-12
 
 Features:
 
 * support "ruby-xxx-jruby-yyy" for jruby detection packages
 
-## v24 (6/7/2012)
+## v24 - 2012-06-07
 
 Features:
 
 * removes bundler cache in the slug, to minimize slug size (@stevenh512, #16)
 * optimize push time with caching
 
-## v23 (5/8/2012)
+## v23 - 2012-05-08
 
 Bugfixes:
 
 * fix ruby version bug with "fatal:-Not-a-git-repository"
 
-## v22 (5/7/2012)
+## v22 - 2012-05-07
 
 Features:
 
@@ -618,25 +1851,25 @@ Deprecation:
 
 * ENV['RUBY_VERSION'] in favor of bundler's ruby DSL
 
-## v21 (3/21/2012)
+## v21 - 2012-03-21
 
 Features:
 
 * bundler 1.1.2
 
-## v20 (3/12/2012)
+## v20 - 2012-03-12
 
 Features:
 
 * bundler 1.1.0 \o/
 
-## v19 (1/25/2012)
+## v19 - 2012-01-25
 
 Bugfixes:
 
 * fix native extension building for rbx 2.0.0dev
 
-## v18 (1/18/2012)
+## v18 - 2012-01-18
 
 Features:
 
@@ -647,49 +1880,49 @@ Bugfixes:
 
 * force db password to be a string in the yaml file
 
-## v17 (12/29/2011)
+## v17 - 2011-12-29
 
 Features:
 
 * bundler 1.1.rc.7
 
-## v16 (12/29/2011)
+## v16 - 2011-12-29
 
 Features:
 
 * pass DATABASE_URL to rails 3.1 assets:precompile rake task detection
 
-## v15 (12/27/2011)
+## v15 - 2011-12-27
 
 Features:
 
 * bundler 1.1.rc.6
 
-## v14 (12/22/2011)
+## v14 - 2011-12-22
 
 Bugfixes:
 
 * stop freedom patching syck in ruby 1.9.3+
 
-## v13 (12/15/2011)
+## v13 - 2011-12-15
 
 Features:
 
 * bundler 1.1.rc.5
 
-## v12 (12/13/2011)
+## v12 - 2011-12-13
 
 Bugfixes:
 
 * syck workaround for yaml/psych issues
 
-## v11 (12/12/2011)
+## v11 - 2011-12-12
 
 Features:
 
 * bundler 1.1.rc.3
 
-## v10 (11/23/2011)
+## v10 - 2011-11-23
 
 Features:
 
@@ -700,7 +1933,7 @@ Bugfixes:
 
 * don't show sqlite3 error if it's in a bundle without group on failed bundle install
 
-## v9 (11/14/2011)
+## v9 - 2011-11-14
 
 Features:
 
@@ -711,13 +1944,13 @@ Bugfixes:
 
 * don't leave behind ruby_versions.yml
 
-## v8 (11/8/2011)
+## v8 - 2011-11-08
 
 Features:
 
 * use vm as part of RUBY_VERSION
 
-## v7 (11/8/2011)
+## v7 - 2011-11-08
 
 Features:
 
@@ -728,7 +1961,7 @@ Bugfixes:
 
 * move "bin/" to the front of the PATH, so apps can override existing bins
 
-## v6 (11/2/2011)
+## v6 - 2011-11-02
 
 Features:
 
@@ -738,3 +1971,170 @@ Bugfixes:
 
 * Change gem detection to use lockfile parser
 * use `$RACK_ENV` when thin is detected for rack apps
+
+[unreleased]: https://github.com/heroku/heroku-buildpack-ruby/compare/v362...main
+[v362]: https://github.com/heroku/heroku-buildpack-ruby/compare/v361...v362
+[v361]: https://github.com/heroku/heroku-buildpack-ruby/compare/v360...v361
+[v360]: https://github.com/heroku/heroku-buildpack-ruby/compare/v359...v360
+[v359]: https://github.com/heroku/heroku-buildpack-ruby/compare/v358...v359
+[v359]: https://github.com/heroku/heroku-buildpack-ruby/compare/v358...v359
+[v358]: https://github.com/heroku/heroku-buildpack-ruby/compare/v357...v358
+[v357]: https://github.com/heroku/heroku-buildpack-ruby/compare/v356...v357
+[v356]: https://github.com/heroku/heroku-buildpack-ruby/compare/v355...v356
+[v355]: https://github.com/heroku/heroku-buildpack-ruby/compare/v354...v355
+[v354]: https://github.com/heroku/heroku-buildpack-ruby/compare/v353...v354
+[v353]: https://github.com/heroku/heroku-buildpack-ruby/compare/v352...v353
+[v352]: https://github.com/heroku/heroku-buildpack-ruby/compare/v351...v352
+[v351]: https://github.com/heroku/heroku-buildpack-ruby/compare/v350...v351
+[v350]: https://github.com/heroku/heroku-buildpack-ruby/compare/v349...v350
+[v349]: https://github.com/heroku/heroku-buildpack-ruby/compare/v348...v349
+[v348]: https://github.com/heroku/heroku-buildpack-ruby/compare/v347...v348
+[v347]: https://github.com/heroku/heroku-buildpack-ruby/compare/v346...v347
+[v346]: https://github.com/heroku/heroku-buildpack-ruby/compare/v345...v346
+[v345]: https://github.com/heroku/heroku-buildpack-ruby/compare/v344...v345
+[v344]: https://github.com/heroku/heroku-buildpack-ruby/compare/v343...v344
+[v343]: https://github.com/heroku/heroku-buildpack-ruby/compare/v342...v343
+[v342]: https://github.com/heroku/heroku-buildpack-ruby/compare/v341...v342
+[v341]: https://github.com/heroku/heroku-buildpack-ruby/compare/v340...v341
+[v340]: https://github.com/heroku/heroku-buildpack-ruby/compare/v339...v340
+[v339]: https://github.com/heroku/heroku-buildpack-ruby/compare/v338...v339
+[v338]: https://github.com/heroku/heroku-buildpack-ruby/compare/v337...v338
+[v337]: https://github.com/heroku/heroku-buildpack-ruby/compare/v336...v337
+[v336]: https://github.com/heroku/heroku-buildpack-ruby/compare/v335...v336
+[v335]: https://github.com/heroku/heroku-buildpack-ruby/compare/v334...v335
+[v334]: https://github.com/heroku/heroku-buildpack-ruby/compare/v333...v334
+[v333]: https://github.com/heroku/heroku-buildpack-ruby/compare/v332...v333
+[v332]: https://github.com/heroku/heroku-buildpack-ruby/compare/v331...v332
+[v331]: https://github.com/heroku/heroku-buildpack-ruby/compare/v330...v331
+[v330]: https://github.com/heroku/heroku-buildpack-ruby/compare/v329...v330
+[v329]: https://github.com/heroku/heroku-buildpack-ruby/compare/v328...v329
+[v328]: https://github.com/heroku/heroku-buildpack-ruby/compare/v327...v328
+[v327]: https://github.com/heroku/heroku-buildpack-ruby/compare/v326...v327
+[v326]: https://github.com/heroku/heroku-buildpack-ruby/compare/v325...v326
+[v325]: https://github.com/heroku/heroku-buildpack-ruby/compare/v324...v325
+[v324]: https://github.com/heroku/heroku-buildpack-ruby/compare/v323...v324
+[v323]: https://github.com/heroku/heroku-buildpack-ruby/compare/v322...v323
+[v322]: https://github.com/heroku/heroku-buildpack-ruby/compare/v321...v322
+[v321]: https://github.com/heroku/heroku-buildpack-ruby/compare/v320...v321
+[v320]: https://github.com/heroku/heroku-buildpack-ruby/compare/v319...v320
+[v319]: https://github.com/heroku/heroku-buildpack-ruby/compare/v318...v319
+[v318]: https://github.com/heroku/heroku-buildpack-ruby/compare/v317...v318
+[v317]: https://github.com/heroku/heroku-buildpack-ruby/compare/v316...v317
+[v316]: https://github.com/heroku/heroku-buildpack-ruby/compare/v315...v316
+[v315]: https://github.com/heroku/heroku-buildpack-ruby/compare/v314...v315
+[v314]: https://github.com/heroku/heroku-buildpack-ruby/compare/v313...v314
+[v313]: https://github.com/heroku/heroku-buildpack-ruby/compare/v312...v313
+[v312]: https://github.com/heroku/heroku-buildpack-ruby/compare/v311...v312
+[v311]: https://github.com/heroku/heroku-buildpack-ruby/compare/v310...v311
+[v310]: https://github.com/heroku/heroku-buildpack-ruby/compare/v309...v310
+[v309]: https://github.com/heroku/heroku-buildpack-ruby/compare/v308...v309
+[v308]: https://github.com/heroku/heroku-buildpack-ruby/compare/v307...v308
+[v307]: https://github.com/heroku/heroku-buildpack-ruby/compare/v306...v307
+[v306]: https://github.com/heroku/heroku-buildpack-ruby/compare/v305...v306
+[v305]: https://github.com/heroku/heroku-buildpack-ruby/compare/v304...v305
+[v304]: https://github.com/heroku/heroku-buildpack-ruby/compare/v303...v304
+[v303]: https://github.com/heroku/heroku-buildpack-ruby/compare/v302...v303
+[v302]: https://github.com/heroku/heroku-buildpack-ruby/compare/v301...v302
+[v301]: https://github.com/heroku/heroku-buildpack-ruby/compare/v300...v301
+[v300]: https://github.com/heroku/heroku-buildpack-ruby/compare/v299...v300
+[v299]: https://github.com/heroku/heroku-buildpack-ruby/compare/v298...v299
+[v298]: https://github.com/heroku/heroku-buildpack-ruby/compare/v297...v298
+[v297]: https://github.com/heroku/heroku-buildpack-ruby/compare/v296...v297
+[v296]: https://github.com/heroku/heroku-buildpack-ruby/compare/v295...v296
+[v295]: https://github.com/heroku/heroku-buildpack-ruby/compare/v294...v295
+[v294]: https://github.com/heroku/heroku-buildpack-ruby/compare/v293...v294
+[v293]: https://github.com/heroku/heroku-buildpack-ruby/compare/v292...v293
+[v292]: https://github.com/heroku/heroku-buildpack-ruby/compare/v291...v292
+[v291]: https://github.com/heroku/heroku-buildpack-ruby/compare/v290...v291
+[v290]: https://github.com/heroku/heroku-buildpack-ruby/compare/v289...v290
+[v289]: https://github.com/heroku/heroku-buildpack-ruby/compare/v288...v289
+[v288]: https://github.com/heroku/heroku-buildpack-ruby/compare/v287...v288
+[v287]: https://github.com/heroku/heroku-buildpack-ruby/compare/v286...v287
+[v286]: https://github.com/heroku/heroku-buildpack-ruby/compare/v285...v286
+[v285]: https://github.com/heroku/heroku-buildpack-ruby/compare/v284...v285
+[v284]: https://github.com/heroku/heroku-buildpack-ruby/compare/v283...v284
+[v283]: https://github.com/heroku/heroku-buildpack-ruby/compare/v282...v283
+[v282]: https://github.com/heroku/heroku-buildpack-ruby/compare/v281...v282
+[v281]: https://github.com/heroku/heroku-buildpack-ruby/compare/v280...v281
+[v280]: https://github.com/heroku/heroku-buildpack-ruby/compare/v279...v280
+[v279]: https://github.com/heroku/heroku-buildpack-ruby/compare/v278...v279
+[v278]: https://github.com/heroku/heroku-buildpack-ruby/compare/v277...v278
+[v277]: https://github.com/heroku/heroku-buildpack-ruby/compare/v276...v277
+[v276]: https://github.com/heroku/heroku-buildpack-ruby/compare/v275...v276
+[v275]: https://github.com/heroku/heroku-buildpack-ruby/compare/v274...v275
+[v274]: https://github.com/heroku/heroku-buildpack-ruby/compare/v273...v274
+[v273]: https://github.com/heroku/heroku-buildpack-ruby/compare/v272...v273
+[v272]: https://github.com/heroku/heroku-buildpack-ruby/compare/v271...v272
+[v271]: https://github.com/heroku/heroku-buildpack-ruby/compare/v270...v271
+[v271]: https://github.com/heroku/heroku-buildpack-ruby/compare/v270...v271
+[v270]: https://github.com/heroku/heroku-buildpack-ruby/compare/v269...v270
+[v269]: https://github.com/heroku/heroku-buildpack-ruby/compare/v268...v269
+[v268]: https://github.com/heroku/heroku-buildpack-ruby/compare/v267...v268
+[v267]: https://github.com/heroku/heroku-buildpack-ruby/compare/v266...v267
+[v266]: https://github.com/heroku/heroku-buildpack-ruby/compare/v265...v266
+[v265]: https://github.com/heroku/heroku-buildpack-ruby/compare/v264...v265
+[v264]: https://github.com/heroku/heroku-buildpack-ruby/compare/v263...v264
+[v263]: https://github.com/heroku/heroku-buildpack-ruby/compare/v262...v263
+[v262]: https://github.com/heroku/heroku-buildpack-ruby/compare/v261...v262
+[v261]: https://github.com/heroku/heroku-buildpack-ruby/compare/v260...v261
+[v260]: https://github.com/heroku/heroku-buildpack-ruby/compare/v259...v260
+[v259]: https://github.com/heroku/heroku-buildpack-ruby/compare/v258...v259
+[v258]: https://github.com/heroku/heroku-buildpack-ruby/compare/v257...v258
+[v257]: https://github.com/heroku/heroku-buildpack-ruby/compare/v256...v257
+[v256]: https://github.com/heroku/heroku-buildpack-ruby/compare/v255...v256
+[v255]: https://github.com/heroku/heroku-buildpack-ruby/compare/v254...v255
+[v254]: https://github.com/heroku/heroku-buildpack-ruby/compare/v253...v254
+[v253]: https://github.com/heroku/heroku-buildpack-ruby/compare/v252...v253
+[v252]: https://github.com/heroku/heroku-buildpack-ruby/compare/v251...v252
+[v251]: https://github.com/heroku/heroku-buildpack-ruby/compare/v250...v251
+[v250]: https://github.com/heroku/heroku-buildpack-ruby/compare/v249...v250
+[v249]: https://github.com/heroku/heroku-buildpack-ruby/compare/v248...v249
+[v248]: https://github.com/heroku/heroku-buildpack-ruby/compare/v247...v248
+[v247]: https://github.com/heroku/heroku-buildpack-ruby/compare/v246...v247
+[v246]: https://github.com/heroku/heroku-buildpack-ruby/compare/v245...v246
+[v245]: https://github.com/heroku/heroku-buildpack-ruby/compare/v244...v245
+[v244]: https://github.com/heroku/heroku-buildpack-ruby/compare/v243...v244
+[v243]: https://github.com/heroku/heroku-buildpack-ruby/compare/v242...v243
+[v242]: https://github.com/heroku/heroku-buildpack-ruby/compare/v241...v242
+[v241]: https://github.com/heroku/heroku-buildpack-ruby/compare/v240...v241
+[v240]: https://github.com/heroku/heroku-buildpack-ruby/compare/v239...v240
+[v239]: https://github.com/heroku/heroku-buildpack-ruby/compare/v238...v239
+[v238]: https://github.com/heroku/heroku-buildpack-ruby/compare/v237...v238
+[v237]: https://github.com/heroku/heroku-buildpack-ruby/compare/v236...v237
+[v236]: https://github.com/heroku/heroku-buildpack-ruby/compare/v235...v236
+[v235]: https://github.com/heroku/heroku-buildpack-ruby/compare/v234...v235
+[v234]: https://github.com/heroku/heroku-buildpack-ruby/compare/v233...v234
+[v233]: https://github.com/heroku/heroku-buildpack-ruby/compare/v232...v233
+[v232]: https://github.com/heroku/heroku-buildpack-ruby/compare/v231...v232
+[v231]: https://github.com/heroku/heroku-buildpack-ruby/compare/v230...v231
+[v230]: https://github.com/heroku/heroku-buildpack-ruby/compare/v229...v230
+[v229]: https://github.com/heroku/heroku-buildpack-ruby/compare/v228...v229
+[v228]: https://github.com/heroku/heroku-buildpack-ruby/compare/v227...v228
+[v227]: https://github.com/heroku/heroku-buildpack-ruby/compare/v226...v227
+[v226]: https://github.com/heroku/heroku-buildpack-ruby/compare/v225...v226
+[v225]: https://github.com/heroku/heroku-buildpack-ruby/compare/v224...v225
+[v224]: https://github.com/heroku/heroku-buildpack-ruby/compare/v223...v224
+[v223]: https://github.com/heroku/heroku-buildpack-ruby/compare/v222...v223
+[v222]: https://github.com/heroku/heroku-buildpack-ruby/compare/v221...v222
+[v221]: https://github.com/heroku/heroku-buildpack-ruby/compare/v220...v221
+[v220]: https://github.com/heroku/heroku-buildpack-ruby/compare/v219...v220
+[v219]: https://github.com/heroku/heroku-buildpack-ruby/compare/v218...v219
+[v218]: https://github.com/heroku/heroku-buildpack-ruby/compare/v217...v218
+[v217]: https://github.com/heroku/heroku-buildpack-ruby/compare/v216...v217
+[v216]: https://github.com/heroku/heroku-buildpack-ruby/compare/v215...v216
+[v215]: https://github.com/heroku/heroku-buildpack-ruby/compare/v214...v215
+[v214]: https://github.com/heroku/heroku-buildpack-ruby/compare/v213...v214
+[v213]: https://github.com/heroku/heroku-buildpack-ruby/compare/v212...v213
+[v212]: https://github.com/heroku/heroku-buildpack-ruby/compare/v211...v212
+[v211]: https://github.com/heroku/heroku-buildpack-ruby/compare/v210...v211
+[v210]: https://github.com/heroku/heroku-buildpack-ruby/compare/v209...v210
+[v209]: https://github.com/heroku/heroku-buildpack-ruby/compare/v208...v209
+[v208]: https://github.com/heroku/heroku-buildpack-ruby/compare/v207...v208
+[v207]: https://github.com/heroku/heroku-buildpack-ruby/compare/v206...v207
+[v206]: https://github.com/heroku/heroku-buildpack-ruby/compare/v205...v206
+[v205]: https://github.com/heroku/heroku-buildpack-ruby/compare/v204...v205
+[v204]: https://github.com/heroku/heroku-buildpack-ruby/compare/v203...v204
+[v203]: https://github.com/heroku/heroku-buildpack-ruby/compare/v202...v203
+[v202]: https://github.com/heroku/heroku-buildpack-ruby/compare/v201...v202
+[v201]: https://github.com/heroku/heroku-buildpack-ruby/compare/v200...v201
+[v200]: https://github.com/heroku/heroku-buildpack-ruby/compare/v199...v200
diff --git a/CODE_OF_CONDUCT.md b/CODE_OF_CONDUCT.md
new file mode 100644
index 000000000..9e229777d
--- /dev/null
+++ b/CODE_OF_CONDUCT.md
@@ -0,0 +1,105 @@
+# Salesforce Open Source Community Code of Conduct
+
+## About the Code of Conduct
+
+Equality is a core value at Salesforce. We believe a diverse and inclusive
+community fosters innovation and creativity, and are committed to building a
+culture where everyone feels included.
+
+Salesforce open-source projects are committed to providing a friendly, safe, and
+welcoming environment for all, regardless of gender identity and expression,
+sexual orientation, disability, physical appearance, body size, ethnicity, nationality,
+race, age, religion, level of experience, education, socioeconomic status, or
+other similar personal characteristics.
+
+The goal of this code of conduct is to specify a baseline standard of behavior so
+that people with different social values and communication styles can work
+together effectively, productively, and respectfully in our open source community.
+It also establishes a mechanism for reporting issues and resolving conflicts.
+
+All questions and reports of abusive, harassing, or otherwise unacceptable behavior
+in a Salesforce open-source project may be reported by contacting the Salesforce
+Open Source Conduct Committee at ossconduct@salesforce.com.
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as
+contributors and maintainers pledge to making participation in our project and
+our community a harassment-free experience for everyone, regardless of gender
+identity and expression, sexual orientation, disability, physical appearance,
+body size, ethnicity, nationality, race, age, religion, level of experience, education,
+socioeconomic status, or other similar personal characteristics.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment
+include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy toward other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or
+advances
+* Personal attacks, insulting/derogatory comments, or trolling
+* Public or private harassment
+* Publishing, or threatening to publish, others' private information—such as
+a physical or electronic address—without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+professional setting
+* Advocating for or encouraging any of the above behaviors
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable
+behavior and are expected to take appropriate and fair corrective action in
+response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or
+reject comments, commits, code, wiki edits, issues, and other contributions
+that are not aligned with this Code of Conduct, or to ban temporarily or
+permanently any contributor for other behaviors that they deem inappropriate,
+threatening, offensive, or harmful.
+
+## Scope
+
+This Code of Conduct applies both within project spaces and in public spaces
+when an individual is representing the project or its community. Examples of
+representing a project or community include using an official project email
+address, posting via an official social media account, or acting as an appointed
+representative at an online or offline event. Representation of a project may be
+further defined and clarified by project maintainers.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported by contacting the Salesforce Open Source Conduct Committee
+at ossconduct@salesforce.com. All complaints will be reviewed and investigated
+and will result in a response that is deemed necessary and appropriate to the
+circumstances. The committee is obligated to maintain confidentiality with
+regard to the reporter of an incident. Further details of specific enforcement
+policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good
+faith may face temporary or permanent repercussions as determined by other
+members of the project's leadership and the Salesforce Open Source Conduct
+Committee.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][contributor-covenant-home],
+version 1.4, available at https://www.contributor-covenant.org/version/1/4/code-of-conduct.html.
+It includes adaptations and additions from [Go Community Code of Conduct][golang-coc],
+[CNCF Code of Conduct][cncf-coc], and [Microsoft Open Source Code of Conduct][microsoft-coc].
+
+This Code of Conduct is licensed under the [Creative Commons Attribution 3.0 License][cc-by-3-us].
+
+[contributor-covenant-home]: https://www.contributor-covenant.org
+[golang-coc]: https://golang.org/conduct
+[cncf-coc]: https://github.com/cncf/foundation/blob/master/code-of-conduct.md
+[microsoft-coc]: https://opensource.microsoft.com/codeofconduct/
+[cc-by-3-us]: https://creativecommons.org/licenses/by/3.0/us/
diff --git a/Gemfile b/Gemfile
index c8b4a4f5f..6075fe158 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,13 +1,18 @@
 source "https://rubygems.org"
+git_source(:github) { |repo| "https://github.com/#{repo}.git" }
+
+ruby "3.3.9"
 
 group :development, :test do
+  gem "toml-rb"
   gem "heroku_hatchet"
   gem "rspec-core"
   gem "rspec-expectations"
   gem "excon"
   gem "rake"
-  gem "parallel_tests"
-  gem 'rspec-retry'
-  gem "netrc"
-  gem "git", github: "hone/ruby-git", branch: "master"
+  gem "parallel_split_test"
+  gem "rspec-retry"
+  gem "json"
+  gem "redis"
+  gem "standard"
 end
diff --git a/Gemfile.lock b/Gemfile.lock
index ea111ea9c..dcd16611b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,79 +1,122 @@
-GIT
-  remote: git://github.com/hone/ruby-git.git
-  revision: 264836fcff3c037d8d8fc44bd770b150b46fdc4e
-  branch: master
-  specs:
-    git (1.2.6)
-
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (4.0.3)
-      i18n (~> 0.6, >= 0.6.4)
-      minitest (~> 4.2)
-      multi_json (~> 1.3)
-      thread_safe (~> 0.1)
-      tzinfo (~> 0.3.37)
-    anvil-cli (0.16.1)
-      progress (~> 2.4.0)
-      rest-client (~> 1.6.7)
-      thor (~> 0.15.2)
-    atomic (1.1.14)
-    diff-lcs (1.1.3)
-    excon (0.31.0)
-    heroku-api (0.3.17)
-      excon (~> 0.27)
-      multi_json (~> 1.8.2)
-    heroku_hatchet (1.3.2)
-      activesupport (~> 4)
-      anvil-cli (~> 0)
-      excon (~> 0)
-      heroku-api (~> 0)
-      repl_runner (~> 0.0.3)
+    ast (2.4.3)
+    base64 (0.3.0)
+    citrus (3.0.2)
+    connection_pool (2.5.3)
+    diff-lcs (1.6.2)
+    erubis (2.7.0)
+    excon (1.6.0)
+      logger
+    heroics (0.1.3)
+      base64
+      erubis (~> 2.0)
+      excon
+      moneta
+      multi_json (>= 1.9.2)
+      webrick
+    heroku_hatchet (8.0.6)
+      excon (< 2)
+      platform-api (~> 3)
       rrrretry (~> 1)
-      thor (~> 0)
+      thor (~> 1)
       threaded (~> 0)
-    i18n (0.6.9)
-    mime-types (2.1)
-    minitest (4.7.5)
-    multi_json (1.8.4)
-    netrc (0.7.7)
-    parallel (0.6.5)
-    parallel_tests (0.13.1)
-      parallel
-    progress (2.4.0)
-    rake (10.0.4)
-    repl_runner (0.0.3)
-      activesupport
-    rest-client (1.6.7)
-      mime-types (>= 1.16)
+    json (2.21.2)
+    language_server-protocol (3.17.0.6)
+    lint_roller (1.1.0)
+    logger (1.7.0)
+    moneta (1.0.0)
+    multi_json (1.17.0)
+    parallel (2.1.0)
+    parallel_split_test (0.10.0)
+      parallel (>= 0.5.13)
+      rspec-core (>= 3.9.0)
+    parser (3.3.12.0)
+      ast (~> 2.4.1)
+      racc
+    platform-api (3.8.0)
+      heroics (~> 0.1.1)
+      moneta (~> 1.0.0)
+      rate_throttle_client (~> 0.1.0)
+    prism (1.9.0)
+    racc (1.8.1)
+    rainbow (3.1.1)
+    rake (13.4.2)
+    rate_throttle_client (0.1.2)
+    redis (5.4.1)
+      redis-client (>= 0.22.0)
+    redis-client (0.25.1)
+      connection_pool
+    regexp_parser (2.12.0)
     rrrretry (1.0.0)
-    rspec (2.2.0)
-      rspec-core (~> 2.2)
-      rspec-expectations (~> 2.2)
-      rspec-mocks (~> 2.2)
-    rspec-core (2.13.1)
-    rspec-expectations (2.12.1)
-      diff-lcs (~> 1.1.3)
-    rspec-mocks (2.13.1)
-    rspec-retry (0.2.1)
-      rspec
-    thor (0.15.4)
-    thread_safe (0.1.3)
-      atomic
+    rspec-core (3.13.6)
+      rspec-support (~> 3.13.0)
+    rspec-expectations (3.13.5)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.13.0)
+    rspec-retry (0.6.2)
+      rspec-core (> 3.3)
+    rspec-support (3.13.6)
+    rubocop (1.88.2)
+      json (~> 2.3)
+      language_server-protocol (~> 3.17.0.2)
+      lint_roller (~> 1.1.0)
+      parallel (>= 1.10)
+      parser (>= 3.3.0.2)
+      rainbow (>= 2.2.2, < 4.0)
+      regexp_parser (>= 2.9.3, < 3.0)
+      rubocop-ast (>= 1.49.0, < 2.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (>= 2.4.0, < 4.0)
+    rubocop-ast (1.50.0)
+      parser (>= 3.3.7.2)
+      prism (~> 1.7)
+    rubocop-performance (1.26.1)
+      lint_roller (~> 1.1)
+      rubocop (>= 1.75.0, < 2.0)
+      rubocop-ast (>= 1.47.1, < 2.0)
+    ruby-progressbar (1.13.0)
+    standard (1.56.0)
+      language_server-protocol (~> 3.17.0.2)
+      lint_roller (~> 1.0)
+      rubocop (~> 1.88.0)
+      standard-custom (~> 1.0.0)
+      standard-performance (~> 1.8)
+    standard-custom (1.0.2)
+      lint_roller (~> 1.0)
+      rubocop (~> 1.50)
+    standard-performance (1.9.0)
+      lint_roller (~> 1.1)
+      rubocop-performance (~> 1.26.0)
+    thor (1.4.0)
     threaded (0.0.4)
-    tzinfo (0.3.38)
+    toml-rb (4.2.0)
+      citrus (~> 3.0, > 3.0)
+      racc (~> 1.7)
+    unicode-display_width (3.2.0)
+      unicode-emoji (~> 4.1)
+    unicode-emoji (4.2.0)
+    webrick (1.9.1)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
   excon
-  git!
   heroku_hatchet
-  netrc
-  parallel_tests
+  json
+  parallel_split_test
   rake
+  redis
   rspec-core
   rspec-expectations
   rspec-retry
+  standard
+  toml-rb
+
+RUBY VERSION
+   ruby 3.3.9p170
+
+BUNDLED WITH
+   2.5.22
diff --git a/README.md b/README.md
index d23812a94..3e4a55d1a 100644
--- a/README.md
+++ b/README.md
@@ -1,10 +1,11 @@
-Heroku buildpack: Ruby
-======================
+# Heroku Buildpack for Ruby
+![ruby](https://raw.githubusercontent.com/heroku/buildpacks/refs/heads/main/assets/images/buildpack-banner-ruby.png)
 
-This is a [Heroku buildpack](http://devcenter.heroku.com/articles/buildpacks) for Ruby, Rack, and Rails apps. It uses [Bundler](http://gembundler.com) for dependency management.
+This is a [Heroku Buildpack](http://devcenter.heroku.com/articles/buildpacks) for Ruby, Rack, and Rails apps. It uses [Bundler](https://bundler.io) for dependency management.
 
-Usage
------
+This buildpack requires 64-bit Linux.
+
+## Usage
 
 ### Ruby
 
@@ -13,9 +14,9 @@ Example Usage:
     $ ls
     Gemfile Gemfile.lock
 
-    $ heroku create --stack cedar --buildpack https://github.com/heroku/heroku-buildpack-ruby.git
+    $ heroku create --buildpack heroku/ruby
 
-    $ git push heroku master
+    $ git push heroku main
     ...
     -----> Heroku receiving push
     -----> Fetching custom buildpack
@@ -31,162 +32,28 @@ Example Usage:
            Procfile declares types -> (none)
            Default types for Ruby  -> console, rake
 
-The buildpack will detect your app as Ruby if it has a `Gemfile` and `Gemfile.lock` files in the root directory. It will then proceed to run `bundle install` after setting up the appropriate environment for [ruby](http://ruby-lang.org) and [Bundler](http://gembundler.com).
+The buildpack will detect your app as Ruby if it has a `Gemfile` and `Gemfile.lock` files in the root directory. It will then proceed to run `bundle install` after setting up the appropriate environment for [ruby](http://ruby-lang.org) and [Bundler](https://bundler.io).
 
-#### Run the Tests
+## Documentation
 
-The tests on this buildpack are written in Rspec to allow the use of
-`focused: true`. Parallelization of testing is provided by
-https://github.com/grosser/parallel_tests this lib spins up an arbitrary
-number of processes and running a different test file in each process,
-it does not parallelize tests within a test file. To run the tests: clone the repo, then `bundle install` then clone the test fixtures by running:
+For more information about using Ruby and buildpacks on Heroku, see these Dev Center articles:
 
-```sh
-$ hatchet install
-```
+- [Heroku Ruby Support](https://devcenter.heroku.com/articles/ruby-support)
+- [Getting Started with Ruby on Heroku](https://devcenter.heroku.com/articles/getting-started-with-ruby)
+- [Getting Started with Rails 7 on Heroku](https://devcenter.heroku.com/articles/getting-started-with-rails7)
+- [Buildpacks](https://devcenter.heroku.com/articles/buildpacks)
+- [Buildpack API](https://devcenter.heroku.com/articles/buildpack-api)
 
-Now run the tests:
+## Hacking
+
+To use this buildpack, fork it on Github.  Push up changes to your fork, then create a test app with `--buildpack <your-github-url>` and push to it.
+
+### Testing
 
 ```sh
-$ bundle exec parallel_rspec -n 6 spec/
+$ bundle exec hatchet install
 ```
 
-If you don't want to run them in parallel you can still:
-
 ```sh
 $ bundle exec rake spec
 ```
-
-Now go take a nap or something for a really long time.
-
-#### Bundler
-
-For non-windows `Gemfile.lock` files, the `--deployment` flag will be used. In the case of windows, the Gemfile.lock will be deleted and Bundler will do a full resolve so native gems are handled properly. The `vendor/bundle` directory is cached between builds to allow for faster `bundle install` times. `bundle clean` is used to ensure no stale gems are stored between builds.
-
-### Rails 2
-
-Example Usage:
-
-    $ ls
-    app  config  db  doc  Gemfile  Gemfile.lock  lib  log  public  Rakefile  README  script  test  tmp  vendor
-
-    $ ls config/environment.rb
-    config/environment.rb
-
-    $ heroku create --stack cedar --buildpack https://github.com/heroku/heroku-buildpack-ruby.git
-
-    $ git push heroku master
-    ...
-    -----> Heroku receiving push
-    -----> Ruby/Rails app detected
-    -----> Installing dependencies using Bundler version 1.1.rc
-    ...
-    -----> Writing config/database.yml to read from DATABASE_URL
-    -----> Rails plugin injection
-           Injecting rails_log_stdout
-    -----> Discovering process types
-           Procfile declares types      -> (none)
-           Default types for Ruby/Rails -> console, rake, web, worker
-
-The buildpack will detect your app as a Rails 2 app if it has a `environment.rb` file in the `config`  directory.
-
-#### Rails Log STDOUT
-  A [rails_log_stdout](http://github.com/ddollar/rails_log_stdout) is installed by default so Rails' logger will log to STDOUT and picked up by Heroku's [logplex](http://github.com/heroku/logplex).
-
-#### Auto Injecting Plugins
-
-Any vendored plugin can be stopped from being installed by creating the directory it's installed to in the slug. For instance, to prevent rails_log_stdout plugin from being injected, add `vendor/plugins/rails_log_stdout/.gitkeep` to your git repo.
-
-### Rails 3
-
-Example Usage:
-
-    $ ls
-    app  config  config.ru  db  doc  Gemfile  Gemfile.lock  lib  log  Procfile  public  Rakefile  README  script  tmp  vendor
-
-    $ ls config/application.rb
-    config/application.rb
-
-    $ heroku create --stack cedar --buildpack https://github.com/heroku/heroku-buildpack-ruby.git
-
-    $ git push heroku master
-    -----> Heroku receiving push
-    -----> Ruby/Rails app detected
-    -----> Installing dependencies using Bundler version 1.1.rc
-           Running: bundle install --without development:test --path vendor/bundle --deployment
-           ...
-    -----> Writing config/database.yml to read from DATABASE_URL
-    -----> Preparing app for Rails asset pipeline
-           Running: rake assets:precompile
-    -----> Rails plugin injection
-           Injecting rails_log_stdout
-           Injecting rails3_serve_static_assets
-    -----> Discovering process types
-           Procfile declares types      -> web
-           Default types for Ruby/Rails -> console, rake, worker
-
-The buildpack will detect your apps as a Rails 3 app if it has an `application.rb` file in the `config` directory.
-
-#### Assets
-
-To enable static assets being served on the dyno, [rails3_serve_static_assets](http://github.com/pedro/rails3_serve_static_assets) is installed by default. If the [execjs gem](http://github.com/sstephenson/execjs) is detected then [node.js](http://github.com/joyent/node) will be vendored. The `assets:precompile` rake task will get run if no `public/manifest.yml` is detected.  See [this article](http://devcenter.heroku.com/articles/rails31_heroku_cedar) on how rails 3.1 works on cedar.
-
-Hacking
--------
-
-To use this buildpack, fork it on Github.  Push up changes to your fork, then create a test app with `--buildpack <your-github-url>` and push to it.
-
-To change the vendored binaries for Bundler, [Node.js](http://github.com/joyent/node), and rails plugins, use the rake tasks provided by the `Rakefile`. You'll need an S3-enabled AWS account and a bucket to store your binaries in as well as the [vulcan](http://github.com/heroku/vulcan) gem to build the binaries on heroku.
-
-For example, you can change the vendored version of Bundler to 1.1.rc.
-
-First you'll need to build a Heroku-compatible version of Node.js:
-
-    $ export AWS_ID=xxx AWS_SECRET=yyy S3_BUCKET=zzz
-    $ s3 create $S3_BUCKET
-    $ rake gem:install[bundler,1.1.rc]
-
-Open `lib/language_pack/ruby.rb` in your editor, and change the following line:
-
-    BUNDLER_VERSION = "1.1.rc"
-
-Open `lib/language_pack/base.rb` in your editor, and change the following line:
-
-    VENDOR_URL = "https://s3.amazonaws.com/zzz"
-
-Commit and push the changes to your buildpack to your Github fork, then push your sample app to Heroku to test.  You should see:
-
-    -----> Installing dependencies using Bundler version 1.1.rc
-
-NOTE: You'll need to vendor the plugins, node, Bundler, and libyaml by running the rake tasks for the buildpack to work properly.
-
-Flow
-----
-
-Here's the basic flow of how the buildpack works:
-
-Ruby (Gemfile and Gemfile.lock is detected)
-
-* runs Bundler
-* installs binaries
-  * installs node if the gem execjs is detected
-* runs `rake assets:precompile` if the rake task is detected
-
-Rack (config.ru is detected)
-
-* everything from Ruby
-* sets RACK_ENV=production
-
-Rails 2 (config/environment.rb is detected)
-
-* everything from Rack
-* sets RAILS_ENV=production
-* install rails 2 plugins
-  * [rails_log_stdout](http://github.com/ddollar/rails_log_stdout)
-
-Rails 3 (config/application.rb is detected)
-
-* everything from Rails 2
-* install rails 3 plugins
-  * [rails3_server_static_assets](https://github.com/pedro/rails3_serve_static_assets)
-
diff --git a/Rakefile b/Rakefile
index cad0c21f8..186bbeb60 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,295 +1,56 @@
+# CAREFUL! Changes made to this file aren't tested
+#
+# If you need new functionality, consider putting it in lib/rake
+# and also adding tests, then calling that code from here
+#
 require "fileutils"
 require "tmpdir"
-require 'hatchet/tasks'
-
-S3_BUCKET_NAME  = "heroku-buildpack-ruby"
-VENDOR_URL      = "https://s3.amazonaws.com/#{S3_BUCKET_NAME}"
-
-def s3_tools_dir
-  File.expand_path("../support/s3", __FILE__)
-end
-
-def s3_upload(tmpdir, name)
-  sh("#{s3_tools_dir}/s3 put #{S3_BUCKET_NAME} #{name}.tgz #{tmpdir}/#{name}.tgz")
-end
-
-def vendor_plugin(git_url, branch = nil)
-  name = File.basename(git_url, File.extname(git_url))
-  Dir.mktmpdir("#{name}-") do |tmpdir|
-    FileUtils.rm_rf("#{tmpdir}/*")
-
-    Dir.chdir(tmpdir) do
-      sh "git clone #{git_url} ."
-      sh "git checkout origin/#{branch}" if branch
-      FileUtils.rm_rf("#{name}/.git")
-      sh("tar czvf #{tmpdir}/#{name}.tgz *")
-      s3_upload(tmpdir, name)
-    end
-  end
-end
-
-def in_gem_env(gem_home, &block)
-  old_gem_home = ENV['GEM_HOME']
-  old_gem_path = ENV['GEM_PATH']
-  ENV['GEM_HOME'] = ENV['GEM_PATH'] = gem_home.to_s
-
-  yield
-
-  ENV['GEM_HOME'] = old_gem_home
-  ENV['GEM_PATH'] = old_gem_path
-end
-
-def install_gem(gem, version)
-  name = "#{gem}-#{version}"
-  Dir.mktmpdir("#{gem}-#{version}") do |tmpdir|
-    Dir.chdir(tmpdir) do |dir|
-      FileUtils.rm_rf("#{tmpdir}/*")
-
-      in_gem_env(tmpdir) do
-        sh("unset RUBYOPT; gem install #{gem} --version #{version} --no-ri --no-rdoc --env-shebang")
-        sh("rm #{gem}-#{version}.gem")
-        sh("rm -rf cache/#{gem}-#{version}.gem")
-        sh("tar czvf #{tmpdir}/#{name}.tgz *")
-        s3_upload(tmpdir, name)
-      end
-    end
-  end
-end
-
-desc "update plugins"
-task "plugins:update" do
-  vendor_plugin "http://github.com/heroku/rails_log_stdout.git", "legacy"
-  vendor_plugin "http://github.com/pedro/rails3_serve_static_assets.git"
-  vendor_plugin "http://github.com/hone/rails31_enable_runtime_asset_compilation.git"
-end
-
-desc "install vendored gem"
-task "gem:install", :gem, :version do |t, args|
-  gem     = args[:gem]
-  version = args[:version]
-
-  install_gem(gem, version)
-end
-
-desc "generate ruby versions manifest"
-task "ruby:manifest" do
-  require 'rexml/document'
-  require 'yaml'
-
-  document = REXML::Document.new(`curl https://#{S3_BUCKET_NAME}.s3.amazonaws.com`)
-  rubies   = document.elements.to_a("//Contents/Key").map {|node| node.text }.select {|text| text.match(/^(ruby|rbx|jruby)-\\\\d+\\\\.\\\\d+\\\\.\\\\d+(-p\\\\d+)?/) }
-
-  Dir.mktmpdir("ruby_versions-") do |tmpdir|
-    name = 'ruby_versions.yml'
-    File.open(name, 'w') {|file| file.puts(rubies.to_yaml) }
-    sh("#{s3_tools_dir}/s3 put #{S3_BUCKET_NAME} #{name} #{name}")
-  end
-end
+require "hatchet/tasks"
+require_relative "lib/rake/deploy_check"
 
 namespace :buildpack do
-  require 'netrc'
-  require 'excon'
-  require 'json'
-  require 'time'
-  require 'cgi'
-  require 'git'
-  require 'fileutils'
-  require 'digest/md5'
-  require 'securerandom'
-
-  def connection
-    @connection ||= begin
-      user, password = Netrc.read["api.heroku.com"]
-      Excon.new("https://#{CGI.escape(user)}:#{password}@buildkits.herokuapp.com")
-    end
+  desc "prepares the next version of the buildpack for release"
+  task :prepare do
+    puts("Use https://github.com/heroku/heroku-buildpack-ruby/actions/workflows/prepare-release.yml")
   end
 
-  def latest_release
-    @latest_release ||= begin
-      buildpack_name = "heroku/ruby"
-      response = connection.get(path: "buildpacks/#{buildpack_name}/revisions")
-      releases = JSON.parse(response.body)
-
-      # {
-      #   "tar_link": "https://codon-buildpacks.s3.amazonaws.com/buildpacks/heroku/ruby-v84.tgz",
-      #   "created_at": "2013-11-06T18:55:04Z",
-      #   "published_by": "richard@heroku.com",
-      #   "id": 84
-      #  }
-      releases.map! do |a|
-        a["created_at"] = Time.parse(a["created_at"])
-        a
-      end.sort! { |a,b| b["created_at"] <=> a["created_at"] }
-      releases.first
-    end
-  end
-
-  def new_version
-    @new_version ||= "v#{latest_release["id"] + 1}"
-  end
-
-  def git
-    @git ||= Git.open(".")
-  end
-
-  desc "increment buildpack version"
-  task :increment do
-    version_file = './lib/language_pack/version'
-    require './lib/language_pack'
-    require version_file
-
-    if LanguagePack::Base::BUILDPACK_VERSION != new_version
-      stashes = nil
-
-      if git.status.changed.any?
-        stashes = Git::Stashes.new(git)
-        stashes.save("WIP")
-      end
-
-      File.open("#{version_file}.rb", 'w') do |file|
-      file.puts <<-FILE
-require "language_pack/base"
-
-# This file is automatically generated by rake
-module LanguagePack
-  class LanguagePack::Base
-    BUILDPACK_VERSION = "#{new_version}"
-  end
-end
-FILE
+  desc "releases the next version of the buildpack"
+  task :release do
+    puts "Checking login state"
+    sh("heroku whoami") do |out, status|
+      if status.success?
+        puts "Success"
+      else
+        raise "Ensure login works: `heroku login`"
       end
-
-      git.add "#{version_file}.rb"
-      git.commit "bump to #{new_version}"
-
-      stashes.pop if stashes
-
-      puts "Bumped to #{new_version}"
-    else
-      puts "Already on #{new_version}"
     end
-  end
-
-  def changelog_entry?
-    File.read("./CHANGELOG.md").split("\n").any? {|line| line.match(/^## #{new_version}/) }
-  end
-
-  desc "check if there's a changelog for the new version"
-  task :changelog do
-    if changelog_entry?
-      puts "Changelog for #{new_version} exists"
-    else
-      puts "Please add a changelog entry for #{new_version}"
-    end
-  end
-
-  def github_remote
-    @github_remote ||= git.remotes.detect {|remote| remote.url.match(%r{heroku/heroku-buildpack-ruby.git$}) }
-
-  end
-
-  def git_push_master
-    puts "Pushing master"
-    git.push(github_remote, 'master', false)
-    $?.success?
-  end
 
-  desc "update master branch"
-  task :git_push_master do
-    git_push_master
-  end
-
-  desc "stage a tarball of the buildpack"
-  task :stage do
-    Dir.mktmpdir("heroku-buildpack-ruby") do |tmpdir|
-      Git.clone(File.expand_path("."), 'heroku-buildpack-ruby', path: tmpdir)
-      Dir.chdir(tmpdir) do |dir|
-        streamer = lambda do |chunk, remaining_bytes, total_bytes|
-          File.open("ruby.tgz", "w") {|file| file.print(chunk) }
-        end
-        Excon.get(latest_release["tar_link"], :response_block => streamer)
-        Dir.chdir("heroku-buildpack-ruby") do |dir|
-          sh "tar xzf ../ruby.tgz .env"
-          sh "tar czf ../buildpack.tgz * .env"
-        end
-
-        @digest = Digest::MD5.hexdigest(File.read("buildpack.tgz"))
+    deploy = DeployCheck.new(github: "heroku/heroku-buildpack-ruby")
+    puts "Attempting to deploy #{deploy.next_version}, overwrite with RELEASE_VERSION env var"
+    deploy.check!
+    if deploy.push_tag?
+      sh("git tag -f #{deploy.next_version}") do |out, status|
+        raise "Could not `git tag -f #{deploy.next_version}`: #{out}" unless status.success?
       end
-
-      filename = "buildpacks/#{@digest}.tgz"
-      puts "Writing to #{filename}"
-      FileUtils.mkdir_p("buildpacks/")
-      FileUtils.cp("#{tmpdir}/buildpack.tgz", filename)
-      FileUtils.cp("#{tmpdir}/buildpack.tgz", "buildpacks/buildpack.tgz")
-    end
-  end
-
-  def multipart_form_data(buildpack_file_path)
-    body = ''
-    boundary = SecureRandom.hex(4)
-    data = File.open(buildpack_file_path)
-
-    data.binmode if data.respond_to?(:binmode)
-    data.pos = 0 if data.respond_to?(:pos=)
-
-    body << "--#{boundary}" << Excon::CR_NL
-    body << %{Content-Disposition: form-data; name="buildpack"; filename="#{File.basename(buildpack_file_path)}"} << Excon::CR_NL
-    body << 'Content-Type: application/x-gtar' << Excon::CR_NL
-    body << Excon::CR_NL
-    body << File.read(buildpack_file_path)
-    body << Excon::CR_NL
-    body << "--#{boundary}--" << Excon::CR_NL
-
-    {
-      :headers => { 'Content-Type' => %{multipart/form-data; boundary="#{boundary}"} },
-      :body => body
-    }
-  end
-
-  desc "publish buildpack"
-  task :publish do
-    buildpack_name = "heroku/ruby"
-    puts "Publishing #{buildpack_name} buildpack"
-    resp = connection.post(multipart_form_data("buildpacks/buildpack.tgz").merge(path: "/buildpacks/#{buildpack_name}"))
-    puts resp.status
-    puts resp.body
-  end
-
-  desc "tag a release"
-  task :tag do
-    tagged_version =
-      if @new_version.nil?
-        "v#{latest_release["id"]}"
-      else
-        new_version
+      sh("git push --tags") do |out, status|
+        raise "Could not `git push --tags`: #{out}" unless status.success?
       end
+    end
 
-    git.add_tag(tagged_version)
-    puts "Created tag #{tagged_version}"
-
-    puts "Pushing tag to remote #{github_remote}"
-    git.push(github_remote, nil, true)
-  end
-
-  desc "release a new version of the buildpack"
-  task :release do
-    Rake::Task["buildpack:increment"].invoke
-    raise "Please add a changelog entry for #{new_version}" unless changelog_entry?
-    raise "Can't push to master" unless git_push_master
-    Rake::Task["buildpack:stage"].invoke
-    Rake::Task["buildpack:publish"].invoke
-    Rake::Task["buildpack:tag"].invoke
+    command = "heroku buildpacks:publish heroku/ruby #{deploy.next_version}"
+    puts "Releasing to heroku: `#{command}`"
+    exec(command)
   end
 end
 
 begin
-  require 'rspec/core/rake_task'
+  require "rspec/core/rake_task"
 
   desc "Run specs"
   RSpec::Core::RakeTask.new(:spec) do |t|
-    t.rspec_opts = %w(-fs --color)
-    #t.ruby_opts  = %w(-w)
+    t.rspec_opts = %w[-fd --color]
+    # t.ruby_opts  = %w(-w)
   end
-  task :default => :spec
-rescue LoadError => e
+  task default: :spec
+rescue LoadError
 end
diff --git a/SECURITY.md b/SECURITY.md
new file mode 100644
index 000000000..72541d6bd
--- /dev/null
+++ b/SECURITY.md
@@ -0,0 +1,7 @@
+# Security
+
+Please report any security issue to [https://www.sfdc.co/SubmitVuln](https://www.sfdc.co/SubmitVuln)
+as soon as it is discovered. This project limits its runtime dependencies in
+order to reduce the total cost of ownership as much as can be, but all consumers
+should remain vigilant and have their security stakeholders review all third-party
+products (3PP) like this one and their dependencies.
diff --git a/bin/compile b/bin/compile
index c603d4e31..d27bd300c 100755
--- a/bin/compile
+++ b/bin/compile
@@ -1,18 +1,48 @@
-#!/usr/bin/env ruby
-
-# sync output
-$stdout.sync = true
-
-$:.unshift File.expand_path("../../lib", __FILE__)
-require "language_pack"
-require "language_pack/shell_helpers"
-
-LanguagePack::Instrument.trace 'compile', 'app.compile' do
-  if pack = LanguagePack.detect(ARGV[0], ARGV[1])
-    LanguagePack::ShellHelpers.initialize_env(ARGV[2])
-    pack.topic("Compiling #{pack.name}")
-    pack.log("compile") do
-      pack.compile
-    end
-  end
-end
+#!/usr/bin/env bash
+# The actual compilation code lives in `bin/support/ruby_compile`. This file instead
+# bootstraps the ruby needed and then executes `bin/support/ruby_compile`
+
+set -euo pipefail
+
+BUILD_DIR=$1
+CACHE_DIR=$2
+ENV_DIR=$3
+BIN_DIR=$(cd "$(dirname "$0")" || exit; pwd) # absolute path
+
+# shellcheck source=bin/support/bash_functions.sh
+source "$BIN_DIR/support/bash_functions.sh"
+
+# Initialize metrics for bin/report
+build_data::init "${CACHE_DIR}"
+build_data::clear
+
+checks::ensure_supported_stack "${STACK:?Required env var STACK is not set}"
+
+bootstrap_ruby_dir=$(mktemp -d)
+if "$BIN_DIR"/support/download_ruby "$BIN_DIR" "$bootstrap_ruby_dir"; then
+  :
+else
+  build_data::kv_string "failure_reason" "bootstrap_ruby_fail"
+  exit 1
+fi
+trap 'rm -rf "$bootstrap_ruby_dir"' EXIT
+
+if detect_needs_java "$BUILD_DIR"; then
+  cat <<EOM
+
+       ## Warning: Your app needs java
+
+       The Ruby buildpack determined your app needs java installed
+       we recommend you add the jvm buildpack to your application:
+
+         $ heroku buildpacks:add heroku/jvm --index=1
+
+-----> Installing Java
+
+EOM
+
+  build_data::kv_string "java_origin" "ruby_buildpack"
+  compile_buildpack_v2 "$BUILD_DIR" "$CACHE_DIR" "$ENV_DIR" "https://buildpack-registry.s3.dualstack.us-east-1.amazonaws.com/buildpacks/heroku/jvm.tgz" "heroku/jvm"
+fi
+
+"$bootstrap_ruby_dir"/bin/ruby "$BIN_DIR/support/ruby_compile.rb" "$@"
diff --git a/bin/detect b/bin/detect
index b87aa5660..c9cb89e18 100755
--- a/bin/detect
+++ b/bin/detect
@@ -1,11 +1,43 @@
-#!/usr/bin/env ruby
+#!/usr/bin/env bash
 
-require 'pathname'
+set -euo pipefail
 
-if Pathname.new(ARGV.first).join("Gemfile").exist?
-  puts "Ruby"
+APP_DIR=$1
+BIN_DIR=$(cd "$(dirname "$0")" || exit; pwd) # absolute path
+
+if [ -f "$APP_DIR/Gemfile" ]; then
+  echo "Ruby"
   exit 0
-else
-  puts "no"
-  exit 1
-end
+fi
+
+# shellcheck source=bin/support/bash_functions.sh
+source "$BIN_DIR/support/bash_functions.sh"
+
+output::error <<EOF
+Error: Your app is configured to use the Ruby buildpack,
+but we couldn't find any supported Ruby project files ('Gemfile' and 'Gemfile.lock').
+
+A Ruby app on Heroku must have a 'Gemfile' and 'Gemfile.lock' in the root directory of its source code.
+
+Currently the root directory of your app contains:
+
+$(ls -1A --indicator-style=slash "${APP_DIR}" || true)
+
+If your app already has a package manager file, check that it:
+
+1. Is in the top level directory (not a subdirectory).
+2. Has the correct spelling (the filenames are case-sensitive).
+3. Isn't listed in '.gitignore' or '.slugignore'.
+4. Has been added to the Git repository using 'git add --all'
+   and then committed using 'git commit'.
+
+Otherwise, add a package manager file to your app. If your app has
+no dependencies, then create an empty 'Gemfile', run 'bundle install' and
+commit the results to git.
+
+For help with using Ruby on Heroku, see:
+https://devcenter.heroku.com/articles/getting-started-with-ruby
+https://devcenter.heroku.com/articles/ruby-support
+EOF
+
+exit 1
diff --git a/bin/release b/bin/release
index c26158a67..e55dd4623 100755
--- a/bin/release
+++ b/bin/release
@@ -1,6 +1,13 @@
-#!/usr/bin/env ruby
+#!/usr/bin/env bash
 
-require 'pathname'
+set -euo pipefail
 
-release = Pathname.new(ARGV.first).join("tmp/heroku-buildpack-release-step.yml")
-puts release.read if release.exist?
+BUILD_DIR="${1:-}"
+RELEASE_FILE="${BUILD_DIR}/tmp/heroku-buildpack-release-step.yml"
+
+# Whilst the release file is always written by the buildpack, some apps use
+# third-party slug cleaner buildpacks to remove this and other files, so we
+# cannot assume it still exists by the time the release step runs.
+if [[ -f "${RELEASE_FILE}" ]]; then
+  cat "${RELEASE_FILE}"
+fi
diff --git a/bin/report b/bin/report
new file mode 100755
index 000000000..6e9bf2662
--- /dev/null
+++ b/bin/report
@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+# Usage: bin/report <build-dir> <cache-dir> <env-dir>
+
+# Produces a build report containing metadata about the build, that's consumed by the build system.
+# This script is run for both successful and failing builds, so it should not assume the build ran
+# to completion (e.g. Python or other tools may not even have been installed).
+#
+# Metrics are collected from the part of the buildpack written in Ruby and the
+# part written in Bash (that is used to bootstrap Ruby). They both write to the
+# same JSON file on disk.
+#
+# Metadata must be emitted to stdout as valid un-nested json (values must not be objects or arrays).
+#
+# Example valid stdout:
+#   {
+#     "ruby_version": "X.Y.Z",
+#     "ruby_install_duration": 1.234
+#   }
+#
+# Failures in this script don't cause the overall build to fail (and won't appear in user
+# facing build logs) to avoid breaking builds unnecessarily / causing confusion. To debug
+# issues check the internal build system logs for `buildpack.report.failed` events, or
+# when developing run `make run` in this repo locally, which runs `bin/report` too.
+
+set -euo pipefail
+
+CACHE_DIR="${2}"
+# The absolute path to the root of the buildpack.
+BIN_DIR=$(cd "$(dirname "$0")" || exit; pwd) # absolute path
+
+# Initialize metrics for bin/report
+# shellcheck source=bin/support/bash_functions.sh
+source "$BIN_DIR/support/bash_functions.sh"
+build_data::init "${CACHE_DIR}"
+build_data::print_bin_report_json
diff --git a/bin/support/bash_functions.sh b/bin/support/bash_functions.sh
new file mode 100755
index 000000000..79f2713a2
--- /dev/null
+++ b/bin/support/bash_functions.sh
@@ -0,0 +1,371 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+ANSI_RED=$'\e[1;31m'
+ANSI_RESET=$'\e[0m'
+
+# Output a styled multi-line error message to stderr.
+#
+# Usage:
+# ```
+# output::error <<-EOF
+# 	Error: The error summary.
+#
+# 	Detailed description.
+# EOF
+# ```
+function output::error() {
+	echo >&2
+	sed -e "s/^/${ANSI_RED} !     /" -e "s/$/${ANSI_RESET}/" >&2
+	echo >&2
+}
+
+curl_retry_on_18() {
+  local ec=18;
+  local attempts=0;
+  while (( ec == 18 && attempts++ < 3 )); do
+    curl "$@" # -C - would return code 33 if unsupported by server
+    ec=$?
+  done
+  return "$ec"
+}
+
+which_java()
+{
+  command -v java > /dev/null
+}
+
+# Detects if a given Gemfile.lock has jruby in it
+# $ cat Gemfile.lock | grep jruby # => ruby 2.5.7p001 (jruby 9.2.13.0)
+detect_needs_java()
+{
+  local app_dir=$1
+  local gemfile_lock="$app_dir/Gemfile.lock"
+  # local needs_jruby=0
+  local skip_java_install=1
+
+  if which_java; then
+    build_data::kv_string "java_origin" "previously_installed"
+    return "$skip_java_install"
+  fi
+
+  grep "(jruby " "$gemfile_lock" --quiet &> /dev/null
+}
+
+# Runs another buildpack against the build dir
+#
+# Example:
+#
+#   compile_buildpack_v2 "$build_dir" "$cache_dir" "$env_dir" "https://buildpack-registry.s3.dualstack.us-east-1.amazonaws.com/buildpacks/heroku/nodejs.tgz" "heroku/nodejs"
+#
+compile_buildpack_v2()
+{
+  local build_dir=$1
+  local cache_dir=$2
+  local env_dir=$3
+  local buildpack=$4
+  local name=$5
+
+  local dir
+  local url
+  local branch
+
+  dir=$(mktemp -t buildpackXXXXX)
+  rm -rf "$dir"
+
+  url=${buildpack%#*}
+  branch=${buildpack#*#}
+
+  if [ "$branch" == "$url" ]; then
+    branch=""
+  fi
+
+  if [ "$url" != "" ]; then
+    echo "-----> Downloading Buildpack: ${name}"
+
+    if [[ "$url" =~ \.tgz$ ]] || [[ "$url" =~ \.tgz\? ]]; then
+      mkdir -p "$dir"
+      if curl_retry_on_18 --no-progress-meter --fail --retry 3 --retry-connrefused --connect-timeout "${CURL_CONNECT_TIMEOUT:-3}" "$url" | tar xz -C "$dir"; then
+        :
+      else
+        echo "Failed to download $url"
+        build_data::kv_string "failure_reason" "compile_buildpack_v2_download_fail"
+        build_data::kv_string "failure_detail" "url: $url"
+        exit 1
+      fi
+    else
+      if git clone --quiet "$url" "$dir"; then
+        :
+      else
+        echo "Failed to clone $url"
+        build_data::kv_string "failure_reason" "compile_buildpack_v2_download_fail"
+        build_data::kv_string "failure_detail" "url: $url"
+        exit 1
+      fi
+    fi
+    cd "$dir" || return
+
+    if [ "$branch" != "" ]; then
+      if git checkout "$branch" >/dev/null 2>&1; then
+        :
+      else
+        echo "Failed to checkout branch $branch"
+        build_data::kv_string "failure_reason" "compile_buildpack_v2_checkout_fail"
+        build_data::kv_string "failure_detail" "buildpack: $buildpack, branch: $branch"
+        exit 1
+      fi
+    fi
+
+    # we'll get errors later if these are needed and don't exist
+    chmod -f +x "$dir/bin/{detect,compile,release}" || true
+
+    if framework=$("$dir"/bin/detect "$build_dir"); then
+      :
+    else
+      echo "Couldn't detect any framework for this buildpack. Exiting."
+      build_data::kv_string "failure_reason" "compile_buildpack_v2_detect_fail"
+      build_data::kv_string "failure_detail" "buildpack: $buildpack"
+
+      exit 1
+    fi
+
+    echo "-----> Detected Framework: $framework"
+    if "$dir"/bin/compile "$build_dir" "$cache_dir" "$env_dir"; then
+      :
+    else
+      echo "Failed to compile with $buildpack"
+      build_data::kv_string "failure_reason" "compile_buildpack_v2_compile_fail"
+      build_data::kv_string "failure_detail" "buildpack: $buildpack"
+      exit 1
+    fi
+
+    # check if the buildpack left behind an environment for subsequent ones
+    if [ -e "$dir/export" ]; then
+      set +u # http://redsymbol.net/articles/unofficial-bash-strict-mode/#sourcing-nonconforming-document
+      # shellcheck disable=SC1091
+      source "$dir/export"
+      set -u # http://redsymbol.net/articles/unofficial-bash-strict-mode/#sourcing-nonconforming-document
+    fi
+
+    if [ -x "$dir/bin/release" ]; then
+      if "$dir"/bin/release "$build_dir" > "$1"/last_pack_release.out; then
+        :
+      else
+        echo "Failed bin/release with $buildpack"
+        build_data::kv_string "failure_reason" "compile_buildpack_v2_release_fail"
+        build_data::kv_string "failure_detail" "buildpack: $buildpack"
+        exit 1
+      fi
+    fi
+  fi
+}
+
+# After a stack is EOL, updates to the buildpack may fail with unexpected or unhelpful errors.
+# This can happen when the buildpack is being used off of the platform such as with `dokku`
+# which is not officially supported.
+function checks::ensure_supported_stack() {
+	local stack="${1}"
+
+	case "${stack}" in
+		# When removing support from a stack, move it to the bottom of the list
+		heroku-22 | heroku-24 | heroku-26)
+			return 0
+			;;
+		heroku-18 | heroku-20)
+			build_data::kv_string "failure_reason" "stack_eol"
+			build_data::kv_string "failure_detail" "${stack} stack"
+			# This error will only ever be seen on non-Heroku environments, since the
+			# Heroku build system rejects builds using EOL stacks.
+			cat <<-EOF
+				Error: The '${stack}' stack is no longer supported.
+
+				This buildpack no longer supports the '${stack}' stack since it has
+				reached its end-of-life:
+				https://devcenter.heroku.com/articles/stack#stack-support-details
+
+				Upgrade to a newer stack to continue using this buildpack.
+			EOF
+			exit 1
+			;;
+		*)
+			build_data::kv_string "failure_reason" "stack_unknown"
+			build_data::kv_string "failure_detail" "${stack} stack"
+			cat <<-EOF
+				Error: The '${stack}' stack isn't recognised.
+
+				This buildpack doesn't recognise or support the '${stack}' stack.
+
+				If '${stack}' is a valid stack, make sure that you are using the latest
+				version of this buildpack and haven't pinned to an older release:
+				https://devcenter.heroku.com/articles/managing-buildpacks#view-your-buildpacks
+				https://devcenter.heroku.com/articles/managing-buildpacks#classic-buildpacks-references
+			EOF
+			exit 1
+			;;
+	esac
+}
+
+## ==============================
+# Start of build_data section
+## ==============================
+
+# Contains functions for storing build data from the buildpack in bash.
+#
+# The format of the report file is JSON.
+#
+# Example:
+#   {
+#     "ruby_version": "3.3.3",
+#     "ruby_install_duration": 1.234
+#   }
+#
+# All keys get `ruby.` prepended to them in the backend automatically.
+
+# Variables shared by this whole module
+BUILD_DATA_FILE="/dev/null"
+# Exported for use by Ruby code
+HEROKU_RUBY_BUILD_REPORT_FILE="/dev/null"
+
+# Must be called before you can use any other methods
+#
+# Usage:
+# ```
+# build_data::init "${CACHE_DIR}"
+# ```
+build_data::init() {
+	local cache_dir="${1}"
+	BUILD_DATA_FILE="${cache_dir}/build-data/ruby.json"
+	HEROKU_RUBY_BUILD_REPORT_FILE="${BUILD_DATA_FILE}"
+
+	# Used later in the `HerokuBuildReport.set_global` call in `bin/support/ruby_compile`
+	export HEROKU_RUBY_BUILD_REPORT_FILE
+}
+
+# Clears any prior build data since it persists between builds
+#
+# Usage:
+# ```
+# build_data::init "${CACHE_DIR}"
+# build_data::clear
+# ```
+build_data::clear() {
+	mkdir -p "$(dirname "${BUILD_DATA_FILE}")"
+	echo "{}" >"${BUILD_DATA_FILE}"
+}
+
+# Adds a key-value pair to the report file without any attempt to quote or escape the value.
+#
+# Usage:
+# ```
+# build_data::kv_raw "ruby_version_major" "3"
+# build_data::kv_raw "ruby_version_default" "true"
+# ```
+build_data::kv_raw() {
+	local key="${1}"
+	local value="${2}"
+	build_report::_set "${key}" "${value}" "false"
+}
+
+# Adds a key-value pair to the report file, quoting the value.
+#
+# Usage:
+# ```
+# build_data::kv_string "ruby_version" "3.3.3"
+# ```
+build_data::kv_string() {
+	local key="${1}"
+	local value="${2}"
+	build_report::_set "${key}" "${value}" "true"
+}
+
+# Internal helper to write a key/value pair to the build data store. The buildpack shouldn't call this directly.
+# Takes a key, value, and a boolean flag indicating whether the value needs to be quoted.
+#
+# Usage:
+# ```
+# build_report::_set "foo_string" "quote me" "true"
+# build_report::_set "bar_number" "99" "false"
+# ```
+function build_report::_set() {
+	local key="${1}"
+	# Truncate the value to an arbitrary 200 characters since it will sometimes contain user-provided
+	# inputs which may be unbounded in size. Ideally individual call sites will perform more aggressive
+	# truncation themselves based on the expected value size, however this is here as a fallback.
+	# (Honeycomb supports string fields up to 64KB in size, however, it's not worth filling up the
+	# build data store or bloating the payload passed back to Vacuole/submitted to Honeycomb given the
+	# extra content in those cases is not normally useful.)
+	local value="${2:0:200}"
+	local needs_quoting="${3}"
+
+	if [[ "${needs_quoting}" == "true" ]]; then
+		# Values passed using `--arg` are treated as strings, and so have double quotes added and any JSON
+		# special characters (such as newlines, carriage returns, double quotes, backslashes) are escaped.
+		local jq_args=(--arg value "${value}")
+	else
+		# Values passed using `--argjson` are treated as raw JSON values, and so aren't escaped or quoted.
+		local jq_args=(--argjson value "${value}")
+	fi
+
+	local new_data_file_contents
+	new_data_file_contents="$(jq --arg key "${key}" "${jq_args[@]}" '. + { ($key): ($value) }' "${BUILD_DATA_FILE}")"
+	echo "${new_data_file_contents}" >"${BUILD_DATA_FILE}"
+}
+
+# Returns the current time since the UNIX Epoch, as a float with microseconds precision.
+#
+# Usage (2025-08-22 11:15 UTC):
+# ```
+# build_data::current_unix_realtime
+# # => 1755879324.771610
+# ```
+build_data::current_unix_realtime() {
+	# We use a subshell with `LC_ALL=C` to ensure the output format isn't affected by system locale.
+	(
+		LC_ALL=C
+		echo "${EPOCHREALTIME}"
+	)
+}
+
+# Adds a key=duration to the report file.
+#
+# Usage:
+# ```
+# start_time=$(build_data::current_unix_realtime)
+# sleep 1
+# build_data::kv_duration_since "ruby_install" "${start_time}"
+#
+# build_data::print_bin_report_json
+# # => { "ruby_install": 1.234 }
+# ```
+build_data::kv_duration_since() {
+	local key="${1}"
+	local start_time="${2}"
+	local end_time duration
+	end_time="$(build_data::current_unix_realtime)"
+	duration="$(awk -v start="${start_time}" -v end="${end_time}" 'BEGIN { printf "%f", (end - start) }')"
+
+	build_data::kv_raw "${key}" "${duration}"
+}
+
+# Prints the build data in JSON format.
+#
+# Usage:
+# ```
+# build_data::print_bin_report_json
+# # => { "ruby_install": 1.234 }
+# ```
+build_data::print_bin_report_json() {
+	if [ "${HEROKU_RUBY_BUILD_REPORT_FILE}" != "${BUILD_DATA_FILE}" ]; then
+		echo "Error: HEROKU_RUBY_BUILD_REPORT_FILE does not match BUILD_DATA_FILE"
+		echo "HEROKU_RUBY_BUILD_REPORT_FILE: ${HEROKU_RUBY_BUILD_REPORT_FILE}"
+		echo "BUILD_DATA_FILE: ${BUILD_DATA_FILE}"
+		exit 1
+	fi
+
+	jq --sort-keys '.' "${BUILD_DATA_FILE}"
+}
+
+## ==============================
+# End of build data section
+## ==============================
diff --git a/bin/support/download_ruby b/bin/support/download_ruby
new file mode 100755
index 000000000..96d8eb770
--- /dev/null
+++ b/bin/support/download_ruby
@@ -0,0 +1,69 @@
+#!/usr/bin/env bash
+
+# Downloads a bootstrap copy of Ruby for execution of the buildpack
+# this is needed so we can totally control the Ruby version and are
+# not dependant on the Ruby version of the stack image
+
+# fail hard
+set -o pipefail
+# fail harder
+set -eu
+
+BIN_DIR=$1
+RUBY_BOOTSTRAP_DIR=$2
+
+# Stack is set by codon, listed here so shellcheck knows about it
+STACK=${STACK:-}
+
+curl_retry_on_18() {
+  local ec=18;
+  local attempts=0;
+  while (( ec == 18 && attempts++ < 3 )); do
+    curl "$@" # -C - would return code 33 if unsupported by server
+    ec=$?
+  done
+  return $ec
+}
+
+ruby_url() {
+  local stack=$1
+  local version=$2
+
+  if [ "$stack" == "heroku-22" ]; then
+    echo "${BUILDPACK_VENDOR_URL:-https://heroku-buildpack-ruby.s3.dualstack.us-east-1.amazonaws.com}/$stack/ruby-$version.tgz"
+  else
+    local arch
+    arch=$(dpkg --print-architecture)
+    echo "${BUILDPACK_VENDOR_URL:-https://heroku-buildpack-ruby.s3.dualstack.us-east-1.amazonaws.com}/$stack/$arch/ruby-$version.tgz"
+  fi
+}
+
+# Pull ruby version out of buildpack.toml to be used with bootstrapping
+regex=".*ruby_version = [\'\"]([0-9]+\.[0-9]+\.[0-9]+)[\'\"].*"
+if [[ $(cat "$BIN_DIR/../buildpack.toml") =~ $regex ]]
+  then
+    heroku_buildpack_ruby_url=$(ruby_url "$STACK" "${BASH_REMATCH[1]}")
+  else
+    heroku_buildpack_ruby_url=""
+    echo "Could not detect ruby version to bootstrap"
+    exit 1
+fi
+
+mkdir -p "$RUBY_BOOTSTRAP_DIR"
+
+if curl_retry_on_18 --fail --retry 3 --retry-connrefused --connect-timeout "${CURL_CONNECT_TIMEOUT:-3}" --no-progress-meter --location --output "$RUBY_BOOTSTRAP_DIR/ruby.tgz" "$heroku_buildpack_ruby_url"; then
+  :
+else
+cat<<EOF
+  Failed to download a Ruby executable for bootstrapping!
+
+  This is most likely a temporary internal error. If the problem
+  persists, make sure that you are not running a custom or forked
+  version of the Heroku Ruby buildpack which may need updating.
+
+  url: $heroku_buildpack_ruby_url
+EOF
+  exit 1
+fi
+
+tar xzf "$RUBY_BOOTSTRAP_DIR/ruby.tgz" -C "$RUBY_BOOTSTRAP_DIR"
diff --git a/bin/support/ruby_compile.rb b/bin/support/ruby_compile.rb
new file mode 100755
index 000000000..036c67dad
--- /dev/null
+++ b/bin/support/ruby_compile.rb
@@ -0,0 +1,32 @@
+#!/usr/bin/env ruby
+
+# This script compiles an application so it can run on Heroku.
+# It will install the application's specified version of Ruby, it's dependencies
+# and certain framework specific requirements (such as calling `rake assets:precompile`
+# for rails apps). You can see all features described in the devcenter
+# https://devcenter.heroku.com/articles/ruby-support
+$stdout.sync = true
+
+$:.unshift File.expand_path("../../../lib", __FILE__)
+require "language_pack"
+require "language_pack/shell_helpers"
+HerokuBuildReport.set_global(
+  path: Pathname(ENV.fetch("HEROKU_RUBY_BUILD_REPORT_FILE"))
+)
+
+begin
+  app_path = Pathname(ARGV[0])
+  cache_path = Pathname(ARGV[1])
+  gemfile_lock = LanguagePack.gemfile_lock(app_path: app_path)
+  Dir.chdir(app_path)
+
+  LanguagePack::ShellHelpers.initialize_env(ARGV[2])
+  LanguagePack.call(
+    app_path: app_path,
+    cache_path: cache_path,
+    gemfile_lock: gemfile_lock,
+    bundle_default_without: "development:test"
+  )
+rescue Exception => e # standard:disable Lint/RescueException
+  LanguagePack::ShellHelpers.display_error_and_exit(e)
+end
diff --git a/bin/support/ruby_test-compile.rb b/bin/support/ruby_test-compile.rb
new file mode 100755
index 000000000..c89d5e9ef
--- /dev/null
+++ b/bin/support/ruby_test-compile.rb
@@ -0,0 +1,36 @@
+#!/usr/bin/env ruby
+
+# This script installs an app's Ruby version and dependencies. It's
+# essentially the same thing as `ruby_compile` (which is called by bin/compile)
+# except that some behavior is cusomtized by the inclusion of the
+# `language_pack/test` file. One difference is dependencies
+# the `bin/compile` installs dependencies via bundler and excludes `development:test`
+# gems, however we need `test` gems to run tests, so instead only `development`
+# is excluded.
+#
+# It also sets up the database (if one is present) and populates the database
+# with the appropriate schema.
+$stdout.sync = true
+
+$:.unshift File.expand_path("../../../lib", __FILE__)
+require "language_pack"
+require "language_pack/shell_helpers"
+require "language_pack/test"
+
+begin
+  app_path = Pathname(ARGV[0])
+  cache_path = Pathname(ARGV[1])
+  gemfile_lock = LanguagePack.gemfile_lock(app_path: app_path)
+  Dir.chdir(app_path)
+
+  LanguagePack::ShellHelpers.initialize_env(ARGV[2])
+  LanguagePack.call(
+    app_path: app_path,
+    cache_path: cache_path,
+    gemfile_lock: gemfile_lock,
+    bundle_default_without: "development",
+    environment_name: "test"
+  )
+rescue Exception => e # standard:disable Lint/RescueException
+  LanguagePack::ShellHelpers.display_error_and_exit(e)
+end
diff --git a/bin/support/ruby_test.rb b/bin/support/ruby_test.rb
new file mode 100755
index 000000000..a80eb6c8c
--- /dev/null
+++ b/bin/support/ruby_test.rb
@@ -0,0 +1,55 @@
+#!/usr/bin/env ruby
+
+# This script will detect which test script or framework an app is likely to be
+# using and run the appropriate command. It is expected that `ruby_test-compile`
+# will be run before this file, this installs a version of Ruby and any dependencies
+# a customer's app needs.
+$stdout.sync = true
+
+$:.unshift File.expand_path("../../../lib", __FILE__)
+require "language_pack"
+require "language_pack/shell_helpers"
+require "language_pack/test"
+require "language_pack/ruby"
+
+include LanguagePack::ShellHelpers # standard:disable Style/MixinUsage
+
+def execute_test(command)
+  topic("Running test: #{command}")
+  execute_command(command)
+  exit $?.exitstatus
+end
+
+def execute_command(command)
+  # Normally the `pipe` command will indent output so that it
+  # matches the build output, however in a test TAP depends on
+  # having no whitespace before output. To avoid adding whitespace
+  # for the original Kernel.puts to be used by passing in the
+  # Kernel object.
+  pipe(command, user_env: true, output_object: Kernel)
+end
+
+# $ bin/test app_path ENV_DIR ARTIFACT_DIR
+app_path, env_dir, _ = ARGV.map { |arg| Pathname(arg).expand_path }
+LanguagePack::ShellHelpers.initialize_env(env_dir)
+Dir.chdir(app_path)
+
+gems_list = LanguagePack::Helpers::BundleList::HumanCommand.new(
+  stream_to_user: false
+).call
+
+execute_test(
+  if gems_list.has_gem?("rspec-core")
+    if File.exist?("bin/rspec")
+      "bin/rspec"
+    else
+      "bundle exec rspec"
+    end
+  elsif File.exist?("bin/rails") && gems_list.has_gem?("railties") && gems_list.gem_version("railties") >= Gem::Version.new("5.x")
+    "bin/rails test"
+  elsif File.exist?("bin/rake")
+    "bin/rake test"
+  else
+    "rake test"
+  end
+)
diff --git a/bin/test b/bin/test
new file mode 100755
index 000000000..2c7f8091d
--- /dev/null
+++ b/bin/test
@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+# The actual `bin/test-compile` code lives in `bin/ruby_test-compile`. This file instead
+# bootstraps the ruby needed and then executes `bin/ruby_test-compile`
+
+set -euo pipefail
+
+BIN_DIR=$(cd "$(dirname "$0")" || exit; pwd) # absolute path
+
+# shellcheck source=bin/support/bash_functions.sh
+source "$BIN_DIR/support/bash_functions.sh"
+
+# The bin/report mechanism is not available in bin/test-compile or bin/test
+# https://github.com/heroku/heroku-buildpack-ruby/pull/1635/files#r2293558218
+#
+# Do not initialize 'build_data::init' here. Without initialization,
+# the build_data calls will write to `/dev/null`, preventing errors.
+# Do not add additional 'build_data::' calls to this file.
+
+bootstrap_ruby_dir=$(mktemp -d)
+"$BIN_DIR"/support/download_ruby "$BIN_DIR" "$bootstrap_ruby_dir"
+trap 'rm -rf "$bootstrap_ruby_dir"' EXIT
+
+"$bootstrap_ruby_dir"/bin/ruby "$BIN_DIR/support/ruby_test.rb" "$@"
diff --git a/bin/test-compile b/bin/test-compile
new file mode 100755
index 000000000..a6ff5edec
--- /dev/null
+++ b/bin/test-compile
@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+# The actual `bin/test-compile` code lives in `bin/ruby_test-compile`. This file instead
+# bootstraps the ruby needed and then executes `bin/ruby_test-compile`
+
+set -euo pipefail
+
+BUILD_DIR=$1
+CACHE_DIR=$2
+ENV_DIR=$3
+BIN_DIR=$(cd "$(dirname "$0")" || exit; pwd) # absolute path
+
+# shellcheck source=bin/support/bash_functions.sh
+source "$BIN_DIR/support/bash_functions.sh"
+
+# The bin/report mechanism is not available in bin/test-compile or bin/test
+# https://github.com/heroku/heroku-buildpack-ruby/pull/1635/files#r2293558218
+#
+# Do not initialize 'build_data::init' here. Without initialization,
+# the build_data calls will write to `/dev/null`, preventing errors.
+# Do not add additional 'build_data::' calls to this file.
+
+bootstrap_ruby_dir=$(mktemp -d)
+"$BIN_DIR"/support/download_ruby "$BIN_DIR" "$bootstrap_ruby_dir"
+trap 'rm -rf "$bootstrap_ruby_dir"' EXIT
+
+if detect_needs_java "$BUILD_DIR"; then
+  cat <<EOM
+
+       ## Warning: Your app needs java
+
+       The Ruby buildpack determined your app needs java installed
+       we recommend you add the jvm buildpack to your application:
+
+         $ heroku buildpacks:add heroku/jvm --index=1
+
+-----> Installing Java
+
+EOM
+
+  compile_buildpack_v2 "$BUILD_DIR" "$CACHE_DIR" "$ENV_DIR" "https://buildpack-registry.s3.dualstack.us-east-1.amazonaws.com/buildpacks/heroku/jvm.tgz" "heroku/jvm"
+fi
+
+"$bootstrap_ruby_dir"/bin/ruby "$BIN_DIR/support/ruby_test-compile.rb" "$@"
diff --git a/buildpack.toml b/buildpack.toml
new file mode 100644
index 000000000..ce9393270
--- /dev/null
+++ b/buildpack.toml
@@ -0,0 +1,15 @@
+[buildpack]
+name = "Ruby"
+ruby_version = "3.3.9"
+
+[publish.Ignore]
+files = [
+  "changelogs/",
+  "spec/",
+  "Gemfile",
+  "Gemfile.lock",
+  "Rakefile",
+  "app.json",
+  "hatchet.json",
+  "hatchet.lock",
+]
diff --git a/changelogs/unreleased/.gitkeep b/changelogs/unreleased/.gitkeep
new file mode 100644
index 000000000..e69de29bb
diff --git a/changelogs/v204/clean_binstubs.md b/changelogs/v204/clean_binstubs.md
new file mode 100644
index 000000000..6c7c3c9cf
--- /dev/null
+++ b/changelogs/v204/clean_binstubs.md
@@ -0,0 +1,5 @@
+## Ruby buildpack now cleans unused binstubs before install
+
+After a Ruby application's dependencies have been installed via `bundle install` the old dependencies are cleaned up by running `bundle clean`. Recently it was discovered that this does not clean up unused binstubs. To correct this problem the Ruby buildpack now manually cleans up generated binstubs in `vendor/bundler/bin`. Then when `bundle install` is executed, only currently used binstubs will be generated.
+
+[Buildpack PR](https://github.com/heroku/heroku-buildpack-ruby/pull/914) and [Heroku Ruby support](https://devcenter.heroku.com/articles/ruby-support).
\ No newline at end of file
diff --git a/changelogs/v204/default_ruby.md b/changelogs/v204/default_ruby.md
new file mode 100644
index 000000000..ac67b0c70
--- /dev/null
+++ b/changelogs/v204/default_ruby.md
@@ -0,0 +1,3 @@
+## Default Ruby version for new apps is now 2.5.6
+
+The [default Ruby version for new Ruby applications is 2.5.6](https://devcenter.heroku.com/articles/ruby-support#default-ruby-version-for-new-apps). You’ll only get the default if the application does not specify a ruby version.
\ No newline at end of file
diff --git a/changelogs/v265/ruby-323.md b/changelogs/v265/ruby-323.md
new file mode 100644
index 000000000..dda99e999
--- /dev/null
+++ b/changelogs/v265/ruby-323.md
@@ -0,0 +1,10 @@
+## Ruby version 3.2.3 is now available
+
+[Ruby v3.2.3](/articles/ruby-support#ruby-versions) is now available on Heroku. To run
+your app using this version of Ruby, add the following `ruby` directive to your Gemfile:
+
+```ruby
+ruby "3.2.3"
+```
+
+For more information on [Ruby 3.2.3, you can view the release announcement](https://www.ruby-lang.org/en/news/).
diff --git a/changelogs/v267/bundler_major_minor.md b/changelogs/v267/bundler_major_minor.md
new file mode 100644
index 000000000..614a9c068
--- /dev/null
+++ b/changelogs/v267/bundler_major_minor.md
@@ -0,0 +1,18 @@
+## Bundler versions 2.4.22 and 2.5.6 are now available for Ruby Applications
+
+The [Ruby Buildpack](https://devcenter.heroku.com/articles/ruby-support#libraries) now installs a version of bundler based on the major and minor version listed in the `Gemfile.lock` under the `BUNDLED WITH` key. Previously, it only used the major version. Now, this logic will be used:
+
+- `BUNDLED WITH` 1.x will receive bundler `1.17.3`
+- `BUNDLED WITH` 2.0.x to 2.3.x will receive bundler `2.3.25`
+- `BUNDLED WITH` 2.4.x will receive bundler `2.4.22`
+- `BUNDLED WITH` 2.5.x and above will receive bundler `2.5.6`
+
+It is strongly recommended that you have both a `RUBY VERSION` and `BUNDLED WITH` version listed in your `Gemfile.lock`. If you do not have those values, you can generate them and commit them to git:
+
+```
+$ bundle update --ruby
+$ git add Gemfile.lock
+$ git commit -m "Update Gemfile.lock"
+```
+
+Applications without these values specified in the `Gemfile.lock` may break unexpectedly when the defaults change.
diff --git a/changelogs/v267/ruby_gemfile_lock.md b/changelogs/v267/ruby_gemfile_lock.md
new file mode 100644
index 000000000..1d9e44101
--- /dev/null
+++ b/changelogs/v267/ruby_gemfile_lock.md
@@ -0,0 +1,15 @@
+## Ruby applications without a `RUBY VERSION` in the Gemfile.lock may receive a default Ruby version
+
+Previously, it was possible to specify a full version of Ruby in the `Gemfile` even if it was not present in the `Gemfile.lock`. The Ruby directive in the `Gemfile` was parsed by bundler and emitted via the command `bundle --platform ruby`. This behavior has changed with bundler `2.4+`, so only ruby versions listed in the `RUBY VERSION` key of the `Gemfile.lock` will be returned. If your application uses bundler 2.4+ and does not have a `RUBY VERSION` specified in the `Gemfile.lock`, it will receive a default version of Ruby.
+
+It is strongly recommended that you have both a `RUBY VERSION` and `BUNDLED WITH` version listed in your `Gemfile.lock`. If you do not have those values, you can generate them and commit them to git:
+
+```
+$ bundle update --ruby
+$ git add Gemfile.lock
+$ git commit -m "Update Gemfile.lock"
+```
+
+Applications without these values specified in the `Gemfile.lock` may break unexpectedly when the defaults change.
+
+If your app relies on specifying the ruby version in the `Gemfile` but not the `Gemfile.lock` and it is not yet using Bundler 2.4+, you may preserve this behavior by not upgrading the bundler version in your `Gemfile.lock`, however, this behavior is deprecated. It will be removed at a future date. It is recommended you lock your Ruby version now to avoid an unexpected breakage in the future.
diff --git a/changelogs/v270/ruby_versions_307_315_324_331.md b/changelogs/v270/ruby_versions_307_315_324_331.md
new file mode 100644
index 000000000..dfe2375c4
--- /dev/null
+++ b/changelogs/v270/ruby_versions_307_315_324_331.md
@@ -0,0 +1,13 @@
+# Ruby versions 3.0.7, 3.1.5, 3.2.4, 3.3.1 are now available
+
+The following Ruby versions are now available on the Heroku platform:
+
+- Ruby 3.0.7
+- Ruby 3.1.5
+- Ruby 3.2.4
+- Ruby 3.3.1
+
+The latest versions are on the [Ruby support page](https://devcenter.heroku.com/articles/ruby-support).
+
+> note
+> [Ruby 3.0.x is now EOL](https://www.ruby-lang.org/en/news/2024/04/23/ruby-3-0-7-released/) and therefore is no longer within Heroku's support policy. Heroku strongly recommends upgrading to Ruby 3.1.x or later.
diff --git a/changelogs/v272/default_ruby.md b/changelogs/v272/default_ruby.md
new file mode 100644
index 000000000..a06f083bb
--- /dev/null
+++ b/changelogs/v272/default_ruby.md
@@ -0,0 +1,3 @@
+## Default Ruby version for new apps is now 3.1.6
+
+The [default Ruby version for new Ruby applications is 3.1.6](https://devcenter.heroku.com/articles/ruby-support#default-ruby-version-for-new-apps). You’ll only get the default if the application does not specify a ruby version.
diff --git a/changelogs/v273/windows_gemfile.md b/changelogs/v273/windows_gemfile.md
new file mode 100644
index 000000000..19920e449
--- /dev/null
+++ b/changelogs/v273/windows_gemfile.md
@@ -0,0 +1,73 @@
+## Native Gemfile.lock support for Windows Ruby users with Bundler 2.2+
+
+Ruby applications that use Windows and Bundler 2.2+ will no longer have their `Gemfile.lock` deleted and re-generated on deployment. Instead, they will rely on Bundler 2.2+'s support for multiple platforms to correctly resolve dependencies. We recommend any Windows Ruby user to upgrade their Bundler version in the `Gemfile.lock` to Bundler 2.2+ to take advantage of this behavior:
+
+> note
+> The leading `>` indicates a command prompt and should not be copied.
+
+```
+> gem install bundler
+> bundle update --bundler
+> bundle lock --add-platform ruby
+> bundle lock --add-platform x86_64-linux
+> bundle install
+> git add Gemfile.lock
+> git commit -m "Upgrade bundler"
+```
+
+This change is reflected in the [Deploying a Ruby Project Generated on Windows](https://devcenter.heroku.com/articles/bundler-windows-gemfile) Dev Center article. More information on the history of the behavior can be found [on this GitHub issue](https://github.com/heroku/heroku-buildpack-ruby/issues/1157).
+
+<!--
+
+https://devcenter.heroku.com/admin/articles/315/edit
+
+# Using Bundler
+
+To use, install bundler run:
+
+> note
+> Commands are prefixed with `>` to indicate they should be run in a command prompt, do not copy the `>` character.
+
+```term
+> gem install bundler
+```
+
+Create a file named `Gemfile` in the root of your app specifying what gems are required to run it:
+
+```ruby
+source "https://rubygems.org"
+
+gem 'sinatra', '4.0'
+```
+
+This file should be added to the git repository since it is part of the app. You should also add the `.bundle` directory to your `.gitignore` file. Once you have added the `Gemfile`, it makes it easy for other developers to get their environment ready to run the app:
+
+```term
+> bundle install
+```
+
+This command ensures that all gems specified in the `Gemfile` are available for your application. Running `bundle install` also generates a `Gemfile.lock`, which should be added to your git repository. The `Gemfile.lock` ensures that deployed versions of gems on Heroku match the version installed locally on your development machine.
+
+>warning
+>If your `Gemfile.lock` specifies a bundler version prior to 2.2 and the `PLATFORMS` section of your `Gemfile.lock` contains Windows entries, such as `mswin` or `mingw`, then the `Gemfile.lock` file will be ignored on Heroku. We recommend upgrading to Bundler 2.2 or later.
+
+## Windows support with Bundler 2.2 and later
+
+Heroku supports deploying applications developed on Windows, but [production dynos will be run on a different operating system](https://devcenter.heroku.com/articles/stack)). To ensure that your Heroku production application installs the same versions of gems you are using locally for development on your Windows machine, we recommend updating your application to Bundler 2.2 or later. You can upgrade your bundler version by running the following commands:
+
+```
+> gem install bundler
+> bundle update --bundler
+> bundle lock --add-platform ruby
+> bundle lock --add-platform x86_64-linux
+> bundle install
+> git add Gemfile.lock
+> git commit -m "Upgrade bundler"
+```
+
+After running these commands, Windows applications using bundler 2.2+ will rely on bundler's support for multiple platforms to find and install an appropriate version.
+
+## Windows support with bundler before 2.2
+
+If your application cannot upgrade to bundler 2.2 or later, then when you deploy, the `Gemfile.lock` file will be deleted and regenerated. More information about [this behavior can be found on the Ruby buildpack's GitHub repository](https://github.com/heroku/heroku-buildpack-ruby/issues/1157).
+-->
diff --git a/changelogs/v274/jruby_93150.md b/changelogs/v274/jruby_93150.md
new file mode 100644
index 000000000..cdc0821f1
--- /dev/null
+++ b/changelogs/v274/jruby_93150.md
@@ -0,0 +1,18 @@
+## JRuby version 9.3.15.0 is now available
+
+[JRuby v9.3.15.0](/articles/ruby-support#ruby-versions) is now available on Heroku. To run
+your app using this version of Ruby, add the following `ruby` directive to your Gemfile:
+
+```ruby
+ruby "2.6.8", engine: "jruby", engine_version: "9.3.15.0"
+```
+
+The JRuby release notes can be found on the [JRuby website](https://www.jruby.org/news).
+
+<!--
+
+https://devcenter.heroku.com/admin/articles/698/edit
+
+* `9.3.15.0`, Ruby Versions: [`2.6.8`]
+
+-->
diff --git a/changelogs/v275/jruby-9.4.8.0.md b/changelogs/v275/jruby-9.4.8.0.md
new file mode 100644
index 000000000..53d205557
--- /dev/null
+++ b/changelogs/v275/jruby-9.4.8.0.md
@@ -0,0 +1,10 @@
+## JRuby version 9.4.8.0 is now available
+
+[JRuby v9.4.8.0](/articles/ruby-support#ruby-versions) is now available on Heroku. To run
+your app using this version of Ruby, add the following `ruby` directive to your Gemfile:
+
+```ruby
+ruby "3.1.4", engine: "jruby", engine_version: "9.4.8.0"
+```
+
+The JRuby release notes can be found on the [JRuby website](https://www.jruby.org/news).
diff --git a/changelogs/v276/ruby_3.3.4.md b/changelogs/v276/ruby_3.3.4.md
new file mode 100644
index 000000000..4a35190b5
--- /dev/null
+++ b/changelogs/v276/ruby_3.3.4.md
@@ -0,0 +1,10 @@
+## Ruby version 3.3.4 is now available
+
+[Ruby v3.3.4](/articles/ruby-support#ruby-versions) is now available on Heroku. To run
+your app using this version of Ruby, add the following `ruby` directive to your Gemfile:
+
+```ruby
+ruby "3.3.4"
+```
+
+For more information on [Ruby 3.3.4, you can view the release announcement](https://www.ruby-lang.org/en/news/).
diff --git a/changelogs/v278/ruby_3.2.5.md b/changelogs/v278/ruby_3.2.5.md
new file mode 100644
index 000000000..e1a140f81
--- /dev/null
+++ b/changelogs/v278/ruby_3.2.5.md
@@ -0,0 +1,10 @@
+## Ruby version 3.2.5 is now available
+
+[Ruby v3.2.5](/articles/ruby-support#ruby-versions) is now available on Heroku. To run
+your app using this version of Ruby, add the following `ruby` directive to your Gemfile:
+
+```ruby
+ruby "3.2.5"
+```
+
+For more information on [Ruby 3.2.5, you can view the release announcement](https://www.ruby-lang.org/en/news/).
diff --git a/changelogs/v279/ruby-3.3.5.md b/changelogs/v279/ruby-3.3.5.md
new file mode 100644
index 000000000..abce00f2d
--- /dev/null
+++ b/changelogs/v279/ruby-3.3.5.md
@@ -0,0 +1,10 @@
+## Ruby version 3.3.5 is now available
+
+[Ruby v3.3.5](/articles/ruby-support#ruby-versions) is now available on Heroku. To run
+your app using this version of Ruby, add the following `ruby` directive to your Gemfile:
+
+```ruby
+ruby "3.3.5"
+```
+
+For more information on [Ruby 3.3.5, you can view the release announcement](https://www.ruby-lang.org/en/news/).
diff --git a/changelogs/v280/ruby-340-preview2.md b/changelogs/v280/ruby-340-preview2.md
new file mode 100644
index 000000000..353e9ad00
--- /dev/null
+++ b/changelogs/v280/ruby-340-preview2.md
@@ -0,0 +1,16 @@
+## Ruby version 3.4.0-preview2 is now available
+
+[Ruby v3.4.0-preview2](/articles/ruby-support#ruby-versions) is now available on Heroku. To run
+your app using this version of Ruby, add the following `ruby` directive to your Gemfile:
+
+```ruby
+ruby "3.4.0.preview2"
+```
+
+For more information on [Ruby 3.4.0-preview2, you can view the release announcement](https://www.ruby-lang.org/en/news/).
+
+> Note
+> This version of Ruby is not suitable for production applications.
+> However, it can be used to test that your application is ready for
+> the official release of Ruby 3.4.0 and
+> to provide feedback to the Ruby core team.
diff --git a/changelogs/v281/ruby-336.md b/changelogs/v281/ruby-336.md
new file mode 100644
index 000000000..9af79b538
--- /dev/null
+++ b/changelogs/v281/ruby-336.md
@@ -0,0 +1,10 @@
+## Ruby version 3.3.6 is now available
+
+[Ruby v3.3.6](/articles/ruby-support#ruby-versions) is now available on Heroku. To run
+your app using this version of Ruby, add the following `ruby` directive to your Gemfile:
+
+```ruby
+ruby "3.3.6"
+```
+
+For more information on [Ruby 3.3.6, you can view the release announcement](https://www.ruby-lang.org/en/news/).
diff --git a/changelogs/v284/node-yarn.md b/changelogs/v284/node-yarn.md
new file mode 100644
index 000000000..b469a66de
--- /dev/null
+++ b/changelogs/v284/node-yarn.md
@@ -0,0 +1,8 @@
+## Ruby apps now default to Node version 22.11.0 and Yarn version 1.22.22
+
+Applications using the `heroku/ruby` buildpack that do not have a version of Node installed by another buildpack (such as the `heroku/nodejs` buildpack) will now receive:
+
+- Node version 22.11.0
+- Yarn version 1.22.22
+
+These versions and instructions on how to specify a specific version of these binaries can be found on the [installed binaries section of the Heroku Ruby Support page](https://devcenter.heroku.com/articles/ruby-support#installed-binaries).
diff --git a/changelogs/v286/3.4.0-rc1.md b/changelogs/v286/3.4.0-rc1.md
new file mode 100644
index 000000000..c26eed3c8
--- /dev/null
+++ b/changelogs/v286/3.4.0-rc1.md
@@ -0,0 +1,15 @@
+## Ruby version 3.4.0-rc1 is now available
+
+[Ruby v3.4.0-rc1](/articles/ruby-support-reference#ruby-versions) is now available on Heroku. To run your app using this version of Ruby, add the following `ruby` directive to your Gemfile:
+
+```ruby
+ruby "3.4.0.rc1"
+```
+
+For more information on [Ruby 3.4.0-rc1, you can view the release announcement](https://www.ruby-lang.org/en/news/).
+
+> Note
+> This version of Ruby is not suitable for production applications.
+> However, it can be used to test that your application is ready for
+> the official release of Ruby 3.4.0 and
+> to provide feedback to the Ruby core team.
diff --git a/changelogs/v287/ruby_3.4.0.md b/changelogs/v287/ruby_3.4.0.md
new file mode 100644
index 000000000..b63ee6503
--- /dev/null
+++ b/changelogs/v287/ruby_3.4.0.md
@@ -0,0 +1,9 @@
+## Ruby version 3.4.0 is now available
+
+[Ruby v3.4.0](/articles/ruby-support-reference#ruby-versions) is now available on Heroku. To run your app using this version of Ruby, add the following `ruby` directive to your Gemfile:
+
+```ruby
+ruby "3.4.0"
+```
+
+For more information on [Ruby 3.4.0, you can view the release announcement](https://www.ruby-lang.org/en/news/).
diff --git a/changelogs/v288/bundler_2.5.23.md b/changelogs/v288/bundler_2.5.23.md
new file mode 100644
index 000000000..9267483f4
--- /dev/null
+++ b/changelogs/v288/bundler_2.5.23.md
@@ -0,0 +1,15 @@
+## Bundler version 2.5.23 is now available for Ruby Applications
+
+The [Ruby Buildpack](https://devcenter.heroku.com/articles/ruby-support#libraries) installs a version of bundler based on the major and minor version listed in the `Gemfile.lock` under the `BUNDLED WITH` key:
+
+- `BUNDLED WITH` 2.5.x will receive bundler `2.5.23`
+
+It is strongly recommended that you have both a `RUBY VERSION` and `BUNDLED WITH` version listed in your `Gemfile.lock`. If you do not have those values, you can generate them and commit them to git:
+
+```
+$ bundle update --ruby
+$ git add Gemfile.lock
+$ git commit -m "Update Gemfile.lock"
+```
+
+Applications without these values specified in the `Gemfile.lock` may break unexpectedly when the defaults change.
diff --git a/changelogs/v288/bundler_2.6.x_support.md b/changelogs/v288/bundler_2.6.x_support.md
new file mode 100644
index 000000000..e9d131563
--- /dev/null
+++ b/changelogs/v288/bundler_2.6.x_support.md
@@ -0,0 +1,15 @@
+## Bundler version 2.6.2 is now available for Ruby Applications
+
+The [Ruby Buildpack](https://devcenter.heroku.com/articles/ruby-support#libraries) installs a version of bundler based on the major and minor version listed in the `Gemfile.lock` under the `BUNDLED WITH` key:
+
+- `BUNDLED WITH` 2.6.x and above will receive bundler `2.6.2`
+
+It is strongly recommended that you have both a `RUBY VERSION` and `BUNDLED WITH` version listed in your `Gemfile.lock`. If you do not have those values, you can generate them and commit them to git:
+
+```
+$ bundle update --ruby
+$ git add Gemfile.lock
+$ git commit -m "Update Gemfile.lock"
+```
+
+Applications without these values specified in the `Gemfile.lock` may break unexpectedly when the defaults change.
diff --git a/changelogs/v289/ruby-3-3-7.md b/changelogs/v289/ruby-3-3-7.md
new file mode 100644
index 000000000..75a40f185
--- /dev/null
+++ b/changelogs/v289/ruby-3-3-7.md
@@ -0,0 +1,9 @@
+## Ruby version 3.3.7 is now available
+
+[Ruby v3.3.7](/articles/ruby-support#ruby-versions) is now available on Heroku. To run your app using this version of Ruby, add the following `ruby` directive to your Gemfile:
+
+```ruby
+ruby "3.3.7"
+```
+
+For more information on [Ruby 3.3.7, you can view the release announcement](https://www.ruby-lang.org/en/news/).
diff --git a/changelogs/v290/jruby-9.4.10.0.md b/changelogs/v290/jruby-9.4.10.0.md
new file mode 100644
index 000000000..2cfa8465b
--- /dev/null
+++ b/changelogs/v290/jruby-9.4.10.0.md
@@ -0,0 +1,10 @@
+## JRuby version 9.4.10.0 is now available
+
+[JRuby v9.4.10.0](/articles/ruby-support-reference#ruby-versions) is now available on Heroku. To run
+your app using this version of Ruby, add the following `ruby` directive to your Gemfile:
+
+```ruby
+ruby "3.1.4", engine: "jruby", engine_version: "9.4.10.0"
+```
+
+The JRuby release notes can be found on the [JRuby website](https://www.jruby.org/news).
diff --git a/changelogs/v291/jruby-9.4.11.0.md b/changelogs/v291/jruby-9.4.11.0.md
new file mode 100644
index 000000000..a4bc9607c
--- /dev/null
+++ b/changelogs/v291/jruby-9.4.11.0.md
@@ -0,0 +1,10 @@
+## JRuby version 9.4.11.0 is now available
+
+[JRuby v9.4.11.0](/articles/ruby-support-reference#ruby-versions) is now available on Heroku. To run
+your app using this version of Ruby, add the following `ruby` directive to your Gemfile:
+
+```ruby
+ruby "3.1.4", engine: "jruby", engine_version: "9.4.11.0"
+```
+
+The JRuby release notes can be found on the [JRuby website](https://www.jruby.org/news).
diff --git a/changelogs/v292/ruby-3.2.7.md b/changelogs/v292/ruby-3.2.7.md
new file mode 100644
index 000000000..1219f91be
--- /dev/null
+++ b/changelogs/v292/ruby-3.2.7.md
@@ -0,0 +1,9 @@
+## Ruby version 3.2.7 is now available
+
+[Ruby v3.2.7](/articles/ruby-support#ruby-versions) is now available on Heroku. To run your app using this version of Ruby, add the following `ruby` directive to your Gemfile:
+
+```ruby
+ruby "3.2.7"
+```
+
+For more information on [Ruby 3.2.7, you can view the release announcement](https://www.ruby-lang.org/en/news/).
diff --git a/changelogs/v293/ruby-3.4.2.md b/changelogs/v293/ruby-3.4.2.md
new file mode 100644
index 000000000..6527e6497
--- /dev/null
+++ b/changelogs/v293/ruby-3.4.2.md
@@ -0,0 +1,9 @@
+## Ruby version 3.4.2 is now available
+
+[Ruby v3.4.2](/articles/ruby-support#ruby-versions) is now available on Heroku. To run your app using this version of Ruby, add the following `ruby` directive to your Gemfile:
+
+```ruby
+ruby "3.4.2"
+```
+
+For more information on [Ruby 3.4.2, you can view the release announcement](https://www.ruby-lang.org/en/news/).
diff --git a/changelogs/v294/bundler_default.md b/changelogs/v294/bundler_default.md
new file mode 100644
index 000000000..03f692719
--- /dev/null
+++ b/changelogs/v294/bundler_default.md
@@ -0,0 +1,13 @@
+## Ruby applications with no specified bundler versions now receive Bundler 2.x
+
+Previously applications with no `BUNDLED WITH` in their `Gemfile.lock` would receive bundler `1.x`. They will now receive the new [default bundler version](https://devcenter.heroku.com/articles/ruby-support-reference#default-bundler-version) `2.3.x`.
+
+It is strongly recommended that you have both a `RUBY VERSION` and `BUNDLED WITH` version listed in your `Gemfile.lock`. If you do not have those values, you can generate them and commit them to git:
+
+```
+$ bundle update --ruby
+$ git add Gemfile.lock
+$ git commit -m "Update Gemfile.lock"
+```
+
+Applications without these values specified in the `Gemfile.lock` may break unexpectedly when the defaults change.
diff --git a/changelogs/v294/default_ruby.md b/changelogs/v294/default_ruby.md
new file mode 100644
index 000000000..9aaf2a5fc
--- /dev/null
+++ b/changelogs/v294/default_ruby.md
@@ -0,0 +1,3 @@
+## Default Ruby version for new apps is now 3.3.7
+
+The [default Ruby version for new Ruby applications is 3.3.7](https://devcenter.heroku.com/articles/ruby-support#default-ruby-version-for-new-apps). You’ll only get the default if the application does not specify a ruby version.
diff --git a/changelogs/v309/default_ruby.md b/changelogs/v309/default_ruby.md
new file mode 100644
index 000000000..92d78578b
--- /dev/null
+++ b/changelogs/v309/default_ruby.md
@@ -0,0 +1,22 @@
+## Default Ruby version for new apps is now 3.3.8
+
+The [default Ruby version for new Ruby applications is 3.3.8](https://devcenter.heroku.com/articles/ruby-support#default-ruby-version-for-new-apps). You’ll only get the default if the application does not specify a Ruby version.
+
+Heroku highly recommends specifying your desired Ruby version. You can specify a Ruby version in your `Gemfile`:
+
+```ruby
+ruby "3.3.9"
+```
+
+Once you have a Ruby version specified in your `Gemfile`, update the `Gemfile.lock` by running the following command:
+
+```term
+$ bundle update --ruby
+```
+
+Make sure you commit the results to git before attempting to deploy again:
+
+```term
+$ git add Gemfile Gemfile.lock
+$ git commit -m "update ruby version"
+```
diff --git a/changelogs/v316/default_v339.md b/changelogs/v316/default_v339.md
new file mode 100644
index 000000000..00e77c025
--- /dev/null
+++ b/changelogs/v316/default_v339.md
@@ -0,0 +1,22 @@
+## Default Ruby version for new apps is now 3.3.9
+
+The [default Ruby version for new Ruby applications is 3.3.9](https://devcenter.heroku.com/articles/ruby-support#default-ruby-version-for-new-apps). You’ll only get the default if the application does not specify a Ruby version.
+
+Heroku highly recommends specifying your desired Ruby version. You can specify a Ruby version in your `Gemfile`:
+
+```ruby
+ruby "3.3.9"
+```
+
+Once you have a Ruby version specified in your `Gemfile`, update the `Gemfile.lock` by running the following command:
+
+```term
+$ bundle update --ruby
+```
+
+Make sure you commit the results to git before attempting to deploy again:
+
+```term
+$ git add Gemfile Gemfile.lock
+$ git commit -m "update ruby version"
+```
diff --git a/changelogs/v320/puma_persistent_timeout.md b/changelogs/v320/puma_persistent_timeout.md
new file mode 100644
index 000000000..dc6e6880c
--- /dev/null
+++ b/changelogs/v320/puma_persistent_timeout.md
@@ -0,0 +1,16 @@
+## Ruby apps now have `PUMA_PERSISTENT_TIMEOUT=95` set by default
+
+All Ruby applications now have `PUMA_PERSISTENT_TIMEOUT` environment variable set to a default value of `95`.
+
+Puma [7.0](https://github.com/puma/puma/pull/3378) introduced the ability to configure the `persistent_timeout` value via an environment variable. Router 2.0 uses an idle timeout value of 90s https://devcenter.heroku.com/articles/http-routing#keepalives. To avoid a situation where a request is sent right before Puma closes the connection, the value needs to be slightly higher than the Router's value.
+
+Applications that are not on Puma 7+ can use it manually in their `config/puma.rb` file:
+
+```ruby
+# config/puma.rb
+
+# Only required for Puma 6 and below
+persistent_timeout(ENV.fetch("PUMA_PERSISTENT_TIMEOUT") || 95)
+```
+
+Other web server users can use this as a stable interface to retrieve a suggested idle timeout setting.
diff --git a/changelogs/v322/persistent-timeout-rails.md b/changelogs/v322/persistent-timeout-rails.md
new file mode 100644
index 000000000..48edf1934
--- /dev/null
+++ b/changelogs/v322/persistent-timeout-rails.md
@@ -0,0 +1,16 @@
+## Rails apps now have `PUMA_PERSISTENT_TIMEOUT=95` set by default
+
+Previously, this setting was only applied to [Rack applications](https://devcenter.heroku.com/changelog-items/3391). With this change, all Ruby applications now have the `PUMA_PERSISTENT_TIMEOUT` environment variable set to a default value of `95`.
+
+Puma [7.0.3+](https://github.com/puma/puma/pull/3378) introduced the ability to configure the `persistent_timeout` value via an environment variable. Router 2.0 uses an idle timeout value of 90s https://devcenter.heroku.com/articles/http-routing#keepalives. To avoid a situation where a request is sent right before Puma closes the connection, the value needs to be slightly higher than the Router's value.
+
+Applications that are not on Puma 7.0.3+ can use it manually in their `config/puma.rb` file:
+
+```ruby
+# config/puma.rb
+
+# Only required for Puma 6 and below
+persistent_timeout(ENV.fetch("PUMA_PERSISTENT_TIMEOUT") { 95 }.to_i)
+```
+
+Other web server users can use this as a stable interface to retrieve a suggested idle timeout setting.
diff --git a/changelogs/v326/bundler-272-269.md b/changelogs/v326/bundler-272-269.md
new file mode 100644
index 000000000..2634de7ee
--- /dev/null
+++ b/changelogs/v326/bundler-272-269.md
@@ -0,0 +1,16 @@
+## Bundler version 2.6.9 and 2.7.2 are now available for Ruby Applications
+
+The [Ruby Buildpack](https://devcenter.heroku.com/articles/ruby-support#libraries) installs a version of bundler based on the major and minor version listed in the `Gemfile.lock` under the `BUNDLED WITH` key:
+
+- `BUNDLED WITH` 2.6.x will receive bundler `2.6.9`
+- `BUNDLED WITH` 2.7.x will receive bundler `2.7.2`
+
+It is strongly recommended that you have both a `RUBY VERSION` and `BUNDLED WITH` version listed in your `Gemfile.lock`. If you do not have those values, you can generate them and commit them to git:
+
+```
+$ bundle update --ruby
+$ git add Gemfile.lock
+$ git commit -m "Update Gemfile.lock"
+```
+
+Applications without these values specified in the `Gemfile.lock` may break unexpectedly when the defaults change.
diff --git a/changelogs/v330/bundler-two-space.md b/changelogs/v330/bundler-two-space.md
new file mode 100644
index 000000000..9c8b0477f
--- /dev/null
+++ b/changelogs/v330/bundler-two-space.md
@@ -0,0 +1,3 @@
+## Support two space `BUNDLED WITH` indented `Gemfile.lock`
+
+The `Gemfile.lock` file generated with the latest version of Bundler [now uses two spaces instead of three](https://github.com/ruby/rubygems/pull/9076). The `heroku/ruby` buildpack now supports this format.
diff --git a/changelogs/v331/bundler-4.0.0.beta2.md b/changelogs/v331/bundler-4.0.0.beta2.md
new file mode 100644
index 000000000..163e01ce5
--- /dev/null
+++ b/changelogs/v331/bundler-4.0.0.beta2.md
@@ -0,0 +1,20 @@
+## Bundler version 4.0.0.beta2 is now available for Ruby Applications
+
+The [Ruby Buildpack](https://devcenter.heroku.com/articles/ruby-support#libraries) installs a version of bundler based on the major and minor version listed in the `Gemfile.lock` under the `BUNDLED WITH` key:
+
+- `BUNDLED WITH` 4.0.x will receive bundler `4.0.0.beta2`
+
+It is strongly recommended that you have both a `RUBY VERSION` and `BUNDLED WITH` version listed in your `Gemfile.lock`. If you do not have those values, you can generate them and commit them to git:
+
+```
+$ bundle update --ruby
+$ git add Gemfile.lock
+$ git commit -m "Update Gemfile.lock"
+```
+
+Applications without these values specified in the `Gemfile.lock` may break unexpectedly when the defaults change.
+
+> Note
+> This version of Bundler is not suitable for production applications.
+> However, it can be used to test that your application is ready for
+> the official release of Bundler 4.0.
diff --git a/changelogs/v333/bundler-4.0.0.md b/changelogs/v333/bundler-4.0.0.md
new file mode 100644
index 000000000..7b10fe4d4
--- /dev/null
+++ b/changelogs/v333/bundler-4.0.0.md
@@ -0,0 +1,16 @@
+## Bundler version 4.0.0 is now available for Ruby Applications
+
+The [Ruby Buildpack](https://devcenter.heroku.com/articles/ruby-support) installs a version of bundler based on the major and minor version listed in the `Gemfile.lock` under the `BUNDLED WITH` key:
+
+- `BUNDLED WITH` 4.0.x will receive bundler `4.0.0`
+
+It is strongly recommended that you have both a `RUBY VERSION` and `BUNDLED WITH` version listed in your `Gemfile.lock`. If you do not have those values, you can generate them and commit them to git:
+
+```
+$ bundle update --ruby
+$ git add Gemfile.lock
+$ git commit -m "Update Gemfile.lock"
+```
+
+Applications without these values specified in the `Gemfile.lock` may break unexpectedly when the defaults change.
+
diff --git a/changelogs/v335/rack-env-ci-test.md b/changelogs/v335/rack-env-ci-test.md
new file mode 100644
index 000000000..ab6b7c636
--- /dev/null
+++ b/changelogs/v335/rack-env-ci-test.md
@@ -0,0 +1,20 @@
+## Heroku CI now sets `RACK_ENV=test` for all Ruby applications
+
+Previously, only Rails applications running on Heroku CI would have `RACK_ENV` and `RAILS_ENV` set to `test`. Non-Rails [Ruby applications](https://devcenter.heroku.com/articles/ruby-support-reference) (such as Sinatra or plain Rack apps) would incorrectly receive `RACK_ENV=production` during CI test runs.
+
+Now, all Ruby applications running on Heroku CI will have `RACK_ENV=test` set by default. This ensures that test-specific configurations are properly loaded and prevents issues with gems like DatabaseCleaner that have safeguards against running in production environments.
+
+If your application relies on the previous behavior, you can explicitly set `RACK_ENV` in your `app.json`:
+
+```json
+{
+  "environments": {
+    "test": {
+      "env": {
+        "RACK_ENV": "production"
+      }
+    }
+  }
+}
+```
+
diff --git a/changelogs/v339/ci-path-order.md b/changelogs/v339/ci-path-order.md
new file mode 100644
index 000000000..f821968f1
--- /dev/null
+++ b/changelogs/v339/ci-path-order.md
@@ -0,0 +1,81 @@
+## Ruby applications using Heroku CI have a different PATH load order
+
+The `PATH` order on Heroku CI relying on `bin/test` interface has changed for applications using the `heroku/ruby` buildpack.
+
+It now starts with:
+
+- `/app/bin:/app/vendor/bundle/bin:/app/vendor/bundle/ruby/<major>.<minor>.0/bin`
+
+> Note `<major>.<minor>` is for the Ruby version so Ruby 3.3.10 would show `/app/vendor/bundle/ruby/3.3.0/bin` on the path .
+
+This matches the behavior of regular `$ git push heroku` deploys and applications specifying a test command via `app.json`.
+
+Previously it started with:
+
+- `/app/bin:vendor/bundle/ruby/<major>.<minor>.0/bin:<bootstrap ruby>/bin:/app/vendor/bundle/ruby/<major>.<minor>.0/bin:/app/vendor/bundle/bin`
+
+This discrepancy between has resulted in zero reported issues or tickets, so the fix is not expected to be disruptive. However, it's still a change, and if your application is affected it helps to understand each of the parts of those path to help with debugging.
+
+## Heroku CI `bin/test`
+
+Only applications that do not specify a test command in their `app.json` will trigger calling `bin/test` of the
+buildpack. This `bin/test` runs a Ruby script to determine what test command should be called (such as `bin/rake test`).
+Applications relying on this behavior will now get a different `PATH` order.
+
+## What is the `PATH`?
+
+When you type in `$ rspec` the operating system will look for the executable `rspec` by breaking the `PATH` environment variable into parts with a colon (`:`) separator in order from back to front. That means that it will now look for the `rspec` executable in this order:
+
+- `/app/bin/rspec`
+- `/app/vendor/bundle/bin/rspec`
+- `/app/vendor/bundle/ruby/<major>.<minor>.0/bin/rspec`
+
+By changing the contents or the ordering of the `PATH` you'll possibly change which executable is run. You can see the executable order by using the `which` tool.
+
+```
+$ heroku run bash
+~ $ which -a rake
+/app/bin/rake
+/app/vendor/bundle/bin/rake
+/app/vendor/bundle/ruby/3.3.0/bin/rake
+```
+
+The `-a` flag tells `which` to list all found executables, not just the first. But when you run `$ rake` it will effectively be the same as calling the full path `$ /app/bin/rake` directly.
+
+## Path parts
+
+The following describes the parts that `heroku/ruby` places on the `PATH` both before and after the change.
+
+### App binstubs `/app/bin`
+
+This is the local `./bin` "binstubs" directory that all recent Rails applications have.
+In addition, the Ruby buildpack also places a symlink to the `ruby` executable we install there, as
+well as other default gems.
+
+This path is first for the current and prior `PATH`.
+
+### Bundler binstubs `/app/vendor/bundle/bin`
+
+The location of binstubs installed by `bundle install`. So if you have `rake` in your `Gemfile` you would get a `/app/vendor/bundle/bin/rake` executable file. Notably, these executables load `bundler/setup`, so if you call `$ /app/vendor/bundle/bin/rake` it's similar to calling `$ bundle exec /app/vendor/bundle/bin/rake`.
+
+Unlike on a local machine, the difference between activating `$ rspec` and `$ bundle exec rspec` is very small, because Heroku cleans unused gem versions. The only time there are multiple versions of a gem on the system is due to default gems or multiple Ruby installations (due to conflicting "bootstrap" Ruby).
+
+This is now second on the `PATH`, previously it was last (as installed by `heroku/ruby`).
+
+> Note that this is bundler version dependent Bundler 2.6 places files here Bundler 2.7+ does not
+
+### RubyGems binstubs`/app/vendor/bundle/ruby/<major>.<minor>.0/bin`
+
+The location of binstubs installed by RubyGems (`gem`). When you `bundle install`, it also installs "binstubs" to this directory. These executables do NOT load bundler, so on Ruby 3.3.10 `$ bundle exec /app/vendor/bundle/ruby/3.3.0/bin/rake` and `$ /app/vendor/bundle/ruby/3.3.0/bin` would possibly produce different results on a system where there are many versions of a default gem installed.
+
+This is now third on the `PATH`, previously it was second as a relative path and again later as an absolute path.
+
+When a relative path is on the `PATH` as the application changes working directories it changes the effective value of the path. For example, `Dir.chdir("tmp")` would trigger path lookups in `tmp/vendor/bundle/ruby/3.3.0/bin` (for Ruby 3.3.10). It's unlikely this affected many people, but the difference is worth noting.
+
+### Bootstrap Ruby `<bootstrap ruby>/bin`
+
+The Ruby buildpack uses a "bootstrap" version of Ruby to execute itself.
+
+Because `/app/bin` is on the path first, the correct version of Ruby will always be used (since that is where we symlink Ruby). However, if you were trying to call a default gem binstub, it's possible that prior to this change, you could have activated the "bootstrap" Ruby's copy instead of the Ruby version you requested.
+
+This is no longer on the path as the implementation was refactored, so it's no longer needed. Previously, it was on the path by necessity of the implementation of `bin/test`.
diff --git a/changelogs/v341/exact-bundler-version.md b/changelogs/v341/exact-bundler-version.md
new file mode 100644
index 000000000..eff3de1a6
--- /dev/null
+++ b/changelogs/v341/exact-bundler-version.md
@@ -0,0 +1,22 @@
+## Ruby applications now receive exact bundler version
+
+The exact bundler version from the `Gemfile.lock` is now installed with no conversion.
+
+If your application fails after this change, you can manually adjust your `BUNDLED WITH` value in the `Gemfile.lock` to match the previously used exact version:
+
+- `BUNDLED WITH 1.x.` installs `bundler 1.17.3`
+- `BUNDLED WITH 2.0.x to 2.3.x` installs `bundler 2.3.25`
+- `BUNDLED WITH 2.4.x` installs `bundler 2.4.22`
+- `BUNDLED WITH 2.5.x` installs `bundler 2.5.23`
+- `BUNDLED WITH 2.6.x` installs `bundler 2.6.9`
+- `BUNDLED WITH 2.7.x` installs `bundler 2.7.2`
+- `BUNDLED WITH 4.0.x` installs `bundler 4.0.0`
+
+For example, if your application started failing, using bundler 2.6.1, you could adjust it to instead use the 2.6.x series above which would be:
+
+```
+BUNDLED WITH
+   2.6.9
+```
+
+Applications without a `BUNDLED WITH` value will receive a [default bundler version ](https://devcenter.heroku.com/articles/ruby-support-reference#default-bundler-version).
diff --git a/changelogs/v345/node-lts-24.md b/changelogs/v345/node-lts-24.md
new file mode 100644
index 000000000..1a19c325c
--- /dev/null
+++ b/changelogs/v345/node-lts-24.md
@@ -0,0 +1,7 @@
+## Ruby apps now default to Node version 24.13.0
+
+Applications using the `heroku/ruby` buildpack that do not have a version of Node installed by another buildpack (such as the `heroku/nodejs` buildpack) will now receive:
+
+- Node version 24.13.0
+
+These versions and instructions on how to specify a specific version of these binaries can be found on the [installed binaries section of the Heroku Ruby Support page](https://devcenter.heroku.com/articles/ruby-support#installed-binaries).
diff --git a/changelogs/v346/bundler_default.md b/changelogs/v346/bundler_default.md
new file mode 100644
index 000000000..fdbb34fc5
--- /dev/null
+++ b/changelogs/v346/bundler_default.md
@@ -0,0 +1,19 @@
+## Ruby applications with no specified bundler versions now receive Bundler 2.5.23
+
+If your `Gemfile.lock` doesn’t include the `BUNDLED WITH` key, Heroku installs a [default bundler version](https://devcenter.heroku.com/articles/ruby-support-reference#default-bundler-version):
+
+- Apps using [Classic Buildpacks](https://devcenter.heroku.com/articles/buildpacks#classic-buildpacks) was `2.3.25` now `2.5.23`
+- Apps using [Cloud Native Buildpacks](https://devcenter.heroku.com/articles/buildpacks#heroku-cloud-native-buildpacks) stays `2.5.23`
+
+>note
+>Ruby's [standard version of bundler](https://stdgems.org/bundler/) takes precedence if it's greater than Heroku's installed version. When there is no `BUNDLED WITH` in the `Gemfile.lock`, then `bundle install` uses the highest version of Bundler available.
+
+It is strongly recommended that you have both a `RUBY VERSION` and `BUNDLED WITH` version listed in your `Gemfile.lock`. If you do not have those values, you can generate them and commit them to git:
+
+```
+$ bundle update --ruby
+$ git add Gemfile.lock
+$ git commit -m "Update Gemfile.lock"
+```
+
+Applications without these values specified in the `Gemfile.lock` may break unexpectedly when the defaults change.
diff --git a/config/cdn.yml b/config/cdn.yml
deleted file mode 100644
index ed97d539c..000000000
--- a/config/cdn.yml
+++ /dev/null
@@ -1 +0,0 @@
----
diff --git a/hatchet.json b/hatchet.json
index 2c201e99b..2dc933628 100644
--- a/hatchet.json
+++ b/hatchet.json
@@ -3,52 +3,40 @@
     "sharpstone/asset_precompile_fail",
     "sharpstone/asset_precompile_pass",
     "sharpstone/asset_precompile_not_found",
-    "sharpstone/database_url_expected_in_rakefile",
     "sharpstone/no_rakefile",
-    "sharpstone/bad_rakefile",
-    "sharpstone/mri_187_no_rake",
-    "sharpstone/mri_187_rake",
-    "sharpstone/mri_200_no_rake",
-    "sharpstone/mri_200_rake"
+    "sharpstone/bad_rakefile"
   ],
   "bundler": [
-    "sharpstone/bad_gemfile_on_platform",
     "sharpstone/git_gemspec",
     "sharpstone/no_lockfile",
-    "sharpstone/sqlite3_gemfile",
-    "sharpstone/nokogiri_160"
+    "sharpstone/sqlite3_gemfile"
   ],
   "ruby": [
-    "sharpstone/mri_187",
-    "sharpstone/ruby_193_jruby_173",
-    "sharpstone/ruby_193_jruby_176"
+    "sharpstone/jruby-minimal",
+    "sharpstone/empty-procfile",
+    "sharpstone/bad_ruby_version"
   ],
   "rack": [
-    "sharpstone/default_ruby",
-    "sharpstone/mri_187_nokogiri",
-    "sharpstone/mri_192",
-    "sharpstone/mri_193",
-    "sharpstone/mri_200",
-    "sharpstone/mri_210"
+    "sharpstone/default_ruby"
   ],
-  "rails2": [
-    "sharpstone/rails23_mri_187"
+  "rails_versions": [
+    "sharpstone/rails_lts_23_default_ruby",
+    "sharpstone/rails3_default_ruby",
+    "sharpstone/rails42_default_ruby",
+    "sharpstone/rails61",
+    "sharpstone/rails-jsbundling",
+    "sharpstone/rails_8_ruby_schema",
+    "sharpstone/rails_8_sql_schema",
+    "sharpstone/rails_8_1_trilogy_db_minimal"
   ],
-  "rails3": [
-    "sharpstone/rails3_mri_193",
-    "sharpstone/railties3_mri_193",
-    "sharpstone/rails3_12factor",
-    "sharpstone/rails3_one_plugin",
-    "sharpstone/rails3_runtime_assets",
-    "sharpstone/rails3-fail-assets-compile"
+  "heroku": [
+    "heroku/ruby-getting-started"
   ],
-  "rails4": [
-    "sharpstone/rails4-manifest",
-    "sharpstone/rails3-to-4-no-bin",
-    "sharpstone/rails4_windows_mri193",
-    "sharpstone/rails4-fail-assets-compile"
+  "node": [
+    "sharpstone/minimal_webpacker"
   ],
-  "rails41": [
-    "sharpstone/rails41_scaffold"
+  "ci": [
+    "sharpstone/heroku-ci-json-example",
+    "sharpstone/ruby_no_rails_test"
   ]
 }
diff --git a/hatchet.lock b/hatchet.lock
new file mode 100644
index 000000000..c59a4d166
--- /dev/null
+++ b/hatchet.lock
@@ -0,0 +1,49 @@
+---
+- - "./repos/bundler/git_gemspec"
+  - 7755e19caf122e1373bce73ffe9b333e9411d732
+- - "./repos/bundler/no_lockfile"
+  - 1947ce9a9c276d5df1c323b2ad78d1d85c7ab4c0
+- - "./repos/bundler/sqlite3_gemfile"
+  - 116db685f54dae18f703b3beb90e64fdbddb048d
+- - "./repos/ci/heroku-ci-json-example"
+  - 728cc99c8e80290cc07441d61a8bcd4596e696fb
+- - "./repos/ci/ruby_no_rails_test"
+  - 8f6b08138db00ef7f3b5a21b1eb42611b83e363b
+- - "./repos/heroku/ruby-getting-started"
+  - main
+- - "./repos/node/minimal_webpacker"
+  - d659577a612b12ddb44ce34e28124c025ecb22f3
+- - "./repos/rack/default_ruby"
+  - master
+- - "./repos/rails_versions/rails-jsbundling"
+  - 50e9fdf7c3a37623c676989ddebac4ee5349734b
+- - "./repos/rails_versions/rails3_default_ruby"
+  - 984b6d02353519251c2d1e885bf8914a2584f26a
+- - "./repos/rails_versions/rails42_default_ruby"
+  - fbdaf031823f09d1514ec1d55dcb04ca2f4264ca
+- - "./repos/rails_versions/rails61"
+  - 47828a3e8c79b7869ca0d9a3afa4be065fa46e96
+- - "./repos/rails_versions/rails_8_1_trilogy_db_minimal"
+  - 3a4ac8b53c68c504b980c4403f6b27b5cf57dd4b
+- - "./repos/rails_versions/rails_8_ruby_schema"
+  - a993a3f00c8e09f733bc3b783f7e37148d0af1d4
+- - "./repos/rails_versions/rails_8_sql_schema"
+  - d5089812196931e858a97119de1640a86825a272
+- - "./repos/rails_versions/rails_lts_23_default_ruby"
+  - f3597fd6f0887763eb65ec2f83a5e9a5155d5625
+- - "./repos/rake/asset_precompile_fail"
+  - 16f7834331d6bb3fc5c284130b14eb1ff74d99d5
+- - "./repos/rake/asset_precompile_not_found"
+  - 57fc7f239bf9319e2f77fe580ba68445f6635191
+- - "./repos/rake/asset_precompile_pass"
+  - ce976c727d9f477957c499f39f4cf9603c378103
+- - "./repos/rake/bad_rakefile"
+  - 3cb9c7bf6494c59bd25fa74c2aa4531119e12a46
+- - "./repos/rake/no_rakefile"
+  - d2ec2084b825218418dac54bd6276ac896b31cdd
+- - "./repos/ruby/bad_ruby_version"
+  - 7bf3470265a87ea6361640aa4bfce6ce3b743520
+- - "./repos/ruby/empty-procfile"
+  - 7cae0aae424c2028b81b5d37ee24d42db8e545b9
+- - "./repos/ruby/jruby-minimal"
+  - 3fa8a57f3dbb4ad6f1db411dca7cdc9b343955ad
diff --git a/lib/heroku_build_report.rb b/lib/heroku_build_report.rb
new file mode 100644
index 000000000..19985194c
--- /dev/null
+++ b/lib/heroku_build_report.rb
@@ -0,0 +1,86 @@
+require "yaml"
+require "json"
+require "pathname"
+
+# Observability reporting for builds
+#
+# Example usage:
+#
+#   HerokuBuildReport::GLOBAL.capture(
+#     "ruby_version" => "3.4.2"
+#   )
+module HerokuBuildReport
+  # Accumulates data in memory and writes it to the specified path in JSON format
+  #
+  # Writes data to disk on every capture. Later `bin/report` emits the disk contents
+  class JsonReport
+    MALFORMED_JSON_KEY = "build_report_file_malformed"
+    attr_reader :data
+
+    def initialize(path:, io: $stdout)
+      @io = io
+      @path = Pathname(path).expand_path
+      @path.dirname.mkpath
+      FileUtils.touch(@path)
+      @data = safe_load(@path.read)
+
+      if @data[MALFORMED_JSON_KEY]
+        @path.write(@data.to_json)
+      end
+    end
+
+    def safe_load(contents)
+      if !contents || contents.empty?
+        {}
+      else
+        JSON.parse(contents)
+      end
+    rescue
+      @io.puts "Internal Warning: Expected build report to be JSON, but it is malformed: #{contents.inspect}"
+      {MALFORMED_JSON_KEY => true}
+    end
+
+    def complex_object?(value)
+      value.to_yaml.match?(/!ruby\/object:/)
+    end
+
+    def capture(metrics = {})
+      metrics.each do |(key, value)|
+        next if key.nil? || key.to_s.strip.empty?
+
+        key = key&.strip
+        raise "Key cannot be empty (#{key.inspect} => #{value})" if key.nil? || key.empty?
+
+        # Don't serialize complex values by accident
+        if complex_object?(value)
+          value = value.to_s
+        end
+
+        @data[key.to_s] = value
+      end
+
+      @path.write(@data.to_json)
+    end
+  end
+
+  # Current load order of the various "language packs"
+  def self.set_global(path:)
+    JsonReport.new(path: path).tap { |report|
+      # Silence warning about setting a constant
+      begin
+        old_verbose = $VERBOSE
+        $VERBOSE = nil
+        const_set(:GLOBAL, report)
+      ensure
+        $VERBOSE = old_verbose
+      end
+    }
+  end
+
+  # Stores data in memory only, does not persist to disk
+  def self.dev_null
+    JsonReport.new(path: "/dev/null")
+  end
+
+  GLOBAL = dev_null # Changed via `set_global`
+end
diff --git a/lib/language_pack.rb b/lib/language_pack.rb
index 7dc3de377..96cb76f1f 100644
--- a/lib/language_pack.rb
+++ b/lib/language_pack.rb
@@ -1,45 +1,164 @@
 require "pathname"
-require 'benchmark'
+require "benchmark"
+
+require "language_pack/shell_helpers"
+require "language_pack/helpers/gemfile_lock"
 
 # General Language Pack module
 module LanguagePack
   module Helpers
   end
 
-  # detects which language pack to use
-  # @param [Array] first argument is a String of the build directory
-  # @return [LanguagePack] the {LanguagePack} detected
-  def self.detect(*args)
-    Instrument.instrument 'detect' do
-      Dir.chdir(args.first)
+  def self.gemfile_lock(app_path:)
+    path = app_path.join("Gemfile.lock")
+    if path.exist?
+      LanguagePack::Helpers::GemfileLock.new(
+        contents: path.read
+      )
+    else
+      raise BuildpackError.new("Gemfile.lock required. Please check it in.")
+    end
+  end
+
+  def self.call(app_path:, cache_path:, gemfile_lock:, bundle_default_without:, environment_name: "production")
+    arch = LanguagePack::Base.get_arch
+    stack = ENV.fetch("STACK")
+    cache = LanguagePack::Cache.new(cache_path)
+    warn_io = LanguagePack::ShellHelpers::WarnIO.new
+    user_env_hash = LanguagePack::ShellHelpers.user_env_hash
+    bundler_cache = LanguagePack::BundlerCache.new(cache, stack)
+    bundler_version = LanguagePack::Helpers::BundlerWrapper.resolve_bundler_version(
+      warn_io: warn_io,
+      gemfile_lock: gemfile_lock
+    )
+
+    metadata = LanguagePack::Metadata.new(cache_path: cache_path)
+    new_app = metadata.empty?
+
+    dot_ruby_version_path = app_path.join(".ruby-version")
+    dot_ruby_version_result = if dot_ruby_version_path.exist?
+      LanguagePack::Helpers::DotRubyVersionFile.new(
+        contents: dot_ruby_version_path.read
+      ).call
+    end
+
+    ruby_version = Ruby.get_ruby_version(
+      report: HerokuBuildReport::GLOBAL,
+      metadata: metadata,
+      gemfile_lock: gemfile_lock,
+      dot_ruby_version_result: dot_ruby_version_result
+    )
 
-      pack = [ NoLockfile, Rails41, Rails4, Rails3, Rails2, Rack, Ruby ].detect do |klass|
-        klass.use?
-      end
+    Ruby.remove_vendor_bundle(app_path: app_path)
+    Ruby.warn_bundler_upgrade(metadata: metadata, bundler_version: bundler_version)
+    Ruby.warn_bad_binstubs(app_path: app_path, warn_object: warn_io)
+    Ruby.warn_bundle_binstub(app_path: app_path, warn_object: warn_io)
+    Ruby.install_ruby(
+      app_path: app_path,
+      ruby_version: ruby_version,
+      stack: stack,
+      arch: arch,
+      metadata: metadata,
+      io: warn_io
+    )
 
-      return pack ? pack.new(*args) : nil
+    bundler = Helpers::BundlerWrapper.new(bundler_path: ruby_version.bundler_directory, bundler_version: bundler_version).install
+    default_config_vars = Ruby.default_config_vars(metadata: metadata, ruby_version: ruby_version, bundler: bundler, environment_name: environment_name)
+    Ruby.setup_language_pack_environment(
+      app_path: app_path.expand_path,
+      ruby_version: ruby_version,
+      user_env_hash: user_env_hash,
+      bundle_default_without: bundle_default_without,
+      default_config_vars: default_config_vars
+    )
+    Ruby.load_bundler_cache(
+      ruby_version: ruby_version,
+      new_app: new_app,
+      cache: cache,
+      metadata: metadata,
+      stack: stack,
+      bundler_cache: bundler_cache,
+      bundler_version: bundler_version,
+      bundler: bundler,
+      io: warn_io
+    )
+
+    bundler_output = "" # buffer
+    Ruby.build_bundler(
+      ruby_version: ruby_version,
+      app_path: app_path,
+      io: warn_io,
+      bundler_cache: bundler_cache,
+      bundler_version: bundler_version,
+      bundler_output: bundler_output
+    )
+
+    Ruby.bundle_list(
+      io: warn_io,
+      stream_to_user: !bundler_output.match?(/Installing|Fetching|Using/)
+    )
+
+    if (pack = LanguagePack.detect(
+      arch: arch,
+      new_app: new_app,
+      warn_io: warn_io,
+      bundler: bundler,
+      app_path: app_path,
+      cache_path: cache_path,
+      ruby_version: ruby_version,
+      gemfile_lock: gemfile_lock,
+      environment_name: environment_name
+    ))
+      pack.topic("Compiling #{pack.name}")
+      pack.compile
     end
   end
 
-end
+  # detects which language pack to use
+  def self.detect(arch:, app_path:, cache_path:, environment_name:, gemfile_lock:, new_app:, ruby_version:, warn_io:, bundler:)
+    pack_klass = [Rails8, Rails7, Rails6, Rails5, Rails4, Rails3, Rails2, Rack, Ruby].detect do |klass|
+      klass.use?(bundler: bundler)
+    end
 
+    pack_klass&.new(
+      arch: arch,
+      bundler: bundler,
+      new_app: new_app,
+      warn_io: warn_io,
+      app_path: app_path,
+      cache_path: cache_path,
+      environment_name: environment_name,
+      gemfile_lock: gemfile_lock,
+      ruby_version: ruby_version
+    )
+  end
+end
 
 $:.unshift File.expand_path("../../vendor", __FILE__)
 $:.unshift File.expand_path("..", __FILE__)
 
-require 'dotenv'
-require 'language_pack/shell_helpers'
-require 'language_pack/instrument'
+require "heroku_build_report"
+
 require "language_pack/helpers/plugin_installer"
 require "language_pack/helpers/stale_file_cleaner"
+require "language_pack/helpers/bundle_list"
 require "language_pack/helpers/rake_runner"
+require "language_pack/helpers/rails_runner"
+require "language_pack/helpers/puma_warn_error"
 require "language_pack/helpers/bundler_wrapper"
+require "language_pack/helpers/lockfile_shell_parser"
+require "language_pack/helpers/default_env_vars"
+require "language_pack/helpers/outdated_ruby_version"
+require "language_pack/helpers/download_presence"
+require "language_pack/helpers/dot_ruby_version_file"
+require "language_pack/installers/heroku_ruby_installer"
 
 require "language_pack/ruby"
 require "language_pack/rack"
 require "language_pack/rails2"
 require "language_pack/rails3"
-require "language_pack/disable_deploys"
 require "language_pack/rails4"
-require "language_pack/rails41"
-require "language_pack/no_lockfile"
+require "language_pack/rails5"
+require "language_pack/rails6"
+require "language_pack/rails7"
+require "language_pack/rails8"
diff --git a/lib/language_pack/base.rb b/lib/language_pack/base.rb
index 4e5d63459..23cc658a5 100644
--- a/lib/language_pack/base.rb
+++ b/lib/language_pack/base.rb
@@ -4,46 +4,60 @@
 require "digest/sha1"
 require "language_pack/shell_helpers"
 require "language_pack/cache"
+require "language_pack/helpers/bundler_cache"
 require "language_pack/metadata"
 require "language_pack/fetcher"
-require "language_pack/instrument"
 
 Encoding.default_external = Encoding::UTF_8 if defined?(Encoding)
 
 # abstract class that all the Ruby based Language Packs inherit from
 class LanguagePack::Base
   include LanguagePack::ShellHelpers
-
-  VENDOR_URL = "https://s3-external-1.amazonaws.com/heroku-buildpack-ruby"
-
-  attr_reader :build_path, :cache
-
-  # changes directory to the build_path
-  # @param [String] the path of the build dir
-  # @param [String] the path of the cache dir this is nil during detect and release
-  def initialize(build_path, cache_path=nil)
-     self.class.instrument "base.initialize" do
-      @build_path   = build_path
-      @cache        = LanguagePack::Cache.new(cache_path) if cache_path
-      @metadata     = LanguagePack::Metadata.new(@cache)
-      @id           = Digest::SHA1.hexdigest("#{Time.now.to_f}-#{rand(1000000)}")[0..10]
-      @warnings     = []
-      @deprecations = []
-      @fetchers     = {:buildpack => LanguagePack::Fetcher.new(VENDOR_URL) }
-
-      Dir.chdir build_path
+  extend LanguagePack::ShellHelpers
+
+  VENDOR_URL = ENV["BUILDPACK_VENDOR_URL"] || "https://heroku-buildpack-ruby.s3.dualstack.us-east-1.amazonaws.com"
+  ROOT_DIR = File.expand_path("../../..", __FILE__)
+  AMD_ONLY_STACKS = ["heroku-22"]
+  KNOWN_ARCHITECTURES = ["amd64", "arm64"]
+
+  attr_reader :app_path, :bundler, :cache, :environment_name, :stack
+
+  def initialize(app_path:, arch:, bundler:, cache_path:, environment_name:, gemfile_lock:, new_app:, ruby_version:, warn_io:)
+    @app_path = app_path
+    @arch = arch
+    @bundler = bundler
+    @environment_name = environment_name
+    @gemfile_lock = gemfile_lock
+    @new_app = new_app
+    @ruby_version = ruby_version
+    @warn_io = warn_io
+    @stack = ENV.fetch("STACK")
+    @cache = LanguagePack::Cache.new(cache_path)
+    @metadata = LanguagePack::Metadata.new(cache_path: cache_path)
+    @bundler_cache = LanguagePack::BundlerCache.new(@cache, @stack)
+    @fetchers = {buildpack: LanguagePack::Fetcher.new(VENDOR_URL)}
+    @report = HerokuBuildReport::GLOBAL
+  end
+
+  def self.get_arch
+    command = "dpkg --print-architecture"
+    arch = run!(command, silent: true).strip
+
+    if !KNOWN_ARCHITECTURES.include?(arch)
+      raise <<~EOF
+        Architecture '#{arch}' returned from command `#{command}` is unknown.
+        Known architectures include: #{KNOWN_ARCHITECTURES.inspect}"
+      EOF
     end
-  end
 
-  def instrument(*args, &block)
-    self.class.instrument(*args, &block)
+    arch
   end
 
-  def self.instrument(*args, &block)
-    LanguagePack::Instrument.instrument(*args, &block)
+  def new_app?
+    @new_app
   end
 
-  def self.===(build_path)
+  def self.===(app_path)
     raise "must subclass"
   end
 
@@ -58,13 +72,6 @@ def default_addons
     raise "must subclass"
   end
 
-  # config vars to be set on first push.
-  # @return [Hash] the result
-  # @not: this is only set the first time an app is pushed to.
-  def default_config_vars
-    raise "must subclass"
-  end
-
   # process types to provide for the app
   # Ex. for rails we provide a web process
   # @return [Hash] the result
@@ -75,61 +82,47 @@ def default_process_types
   # this is called to build the slug
   def compile
     write_release_yaml
-    instrument 'base.compile' do
-      if @warnings.any?
-        topic "WARNINGS:"
-        puts @warnings.join("\n")
-      end
-      if @deprecations.any?
-        topic "DEPRECATIONS:"
-        puts @deprecations.join("\n")
-      end
+    Kernel.puts ""
+    warnings.each do |warning|
+      Kernel.puts "\e[1m\e[33m###### WARNING:\e[0m" # Bold yellow
+      Kernel.puts ""
+      puts warning
+      Kernel.puts ""
     end
+    Kernel.puts ""
   end
 
-  def write_release_yaml
+  def build_release
     release = {}
-    release["addons"]                = default_addons
+    release["addons"] = default_addons
     release["default_process_types"] = default_process_types
-    release["config_vars"]           = default_config_vars
-    FileUtils.mkdir("tmp") unless File.exists?("tmp")
-    File.open("tmp/heroku-buildpack-release-step.yml", 'w') do |f|
-      f.write(release.to_yaml)
-    end
-  end
 
-  # log output
-  # Ex. log "some_message", "here", :someattr="value"
-  def log(*args)
-    args.concat [:id => @id]
-    args.concat [:framework => self.class.to_s.split("::").last.downcase]
-
-    start = Time.now.to_f
-    log_internal args, :start => start
-
-    if block_given?
-      begin
-        ret = yield
-        finish = Time.now.to_f
-        log_internal args, :status => "complete", :finish => finish, :elapsed => (finish - start)
-        return ret
-      rescue StandardError => ex
-        finish = Time.now.to_f
-        log_internal args, :status => "error", :finish => finish, :elapsed => (finish - start), :message => ex.message
-        raise ex
-      end
-    end
+    release
   end
 
-private ##################################
+  def write_release_yaml
+    release = build_release
+    FileUtils.mkdir("tmp") unless File.exist?("tmp")
+    File.write("tmp/heroku-buildpack-release-step.yml", release.to_yaml)
 
-  # sets up the environment variables for the build process
-  def setup_language_pack_environment
+    warn_webserver
   end
 
-  def add_to_profiled(string)
-    FileUtils.mkdir_p "#{build_path}/.profile.d"
-    File.open("#{build_path}/.profile.d/ruby.sh", "a") do |file|
+  def warn_webserver
+    return if File.exist?("Procfile")
+    msg = "No Procfile detected, using the default web server.\n"
+    msg << "We recommend explicitly declaring how to boot your server process via a Procfile.\n"
+    msg << "https://devcenter.heroku.com/articles/ruby-default-web-server"
+    warn msg
+  end
+
+  private ##################################
+
+  def add_to_profiled(string, filename: "ruby.sh", mode: "a")
+    profiled_path = "#{app_path}/.profile.d/"
+
+    FileUtils.mkdir_p profiled_path
+    File.open("#{profiled_path}/#{filename}", mode) do |file|
       file.puts string
     end
   end
@@ -139,23 +132,43 @@ def set_env_default(key, val)
   end
 
   def set_env_override(key, val)
-    add_to_profiled %{export #{key}="#{val.gsub('"','\"')}"}
+    add_to_profiled %(export #{key}="#{val.gsub('"', '\"')}")
   end
 
-  def log_internal(*args)
-    message = build_log_message(args)
-    %x{ logger -p user.notice -t "slugc[$$]" "buildpack-ruby #{message}" }
+  def add_to_export(string)
+    export = File.join(ROOT_DIR, "export")
+    File.open(export, "a") do |file|
+      file.puts string
+    end
   end
 
-  def build_log_message(args)
-    args.map do |arg|
-      case arg
-        when Float then "%0.2f" % arg
-        when Array then build_log_message(arg)
-        when Hash  then arg.map { |k,v| "#{k}=#{build_log_message([v])}" }.join(" ")
-        else arg
+  # option can be :path, :default, :override
+  # https://github.com/buildpacks/spec/blob/366ac1aa0be59d11010cc21aa06c16d81d8d43e7/buildpack.md#environment-variable-modification-rules
+  def export(key, val, option: nil)
+    string =
+      if option == :default
+        %(export #{key}="${#{key}:-#{val}}")
+      elsif option == :path
+        %(export #{key}="#{val}:$#{key}")
+      else
+        %(export #{key}="#{val.gsub('"', '\"')}")
       end
-    end.join(" ")
+
+    export = File.join(ROOT_DIR, "export")
+    File.open(export, "a") do |file|
+      file.puts string
+    end
+  end
+
+  def set_export_default(key, val)
+    export key, val, option: :default
   end
-end
 
+  def set_export_override(key, val)
+    export key, val, option: :override
+  end
+
+  def set_export_path(key, val)
+    export key, val, option: :path
+  end
+end
diff --git a/lib/language_pack/cache.rb b/lib/language_pack/cache.rb
index 912daa120..a849c37e4 100644
--- a/lib/language_pack/cache.rb
+++ b/lib/language_pack/cache.rb
@@ -1,45 +1,98 @@
 require "pathname"
 require "language_pack"
 
+# Manipulates/handles contents of the cache directory
 class LanguagePack::Cache
+  # @param [String] path to the cache store
   def initialize(cache_path)
-    @cache_base = Pathname.new(cache_path)
+    @cache_base = if cache_path
+      Pathname.new(cache_path)
+    end
   end
 
-  # removes the the specified
+  # removes the the specified path from the cache
   # @param [String] relative path from the cache_base
   def clear(path)
+    return unless @cache_base
+
     target = (@cache_base + path)
     target.exist? && target.rmtree
   end
 
-  # write cache contents
+  # Overwrite cache contents
+  # When called the cache destination will be cleared and the new contents coppied over
+  # This method is perferable as LanguagePack::Cache#add can cause accidental cache bloat.
+  #
   # @param [String] path of contents to store. it will be stored using this a relative path from the cache_base.
-  # @param [Boolean] defaults to true. if set to true, the cache store directory will be cleared before writing to it.
-  def store(path, clear_first=true)
-    clear(path) if clear_first
-    copy path, (@cache_base + path)
+  # @param [String] relative path to store the cache contents, if nil it will assume the from path
+  def store(from, path = nil)
+    return unless @cache_base
+
+    path ||= from
+    clear path
+    copy from, (@cache_base + path)
+  end
+
+  # Adds file to cache without clearing the destination
+  # Use LanguagePack::Cache#store to avoid accidental cache bloat
+  def add(from, path = nil)
+    return unless @cache_base
+
+    path ||= from
+    copy from, (@cache_base + path)
   end
 
   # load cache contents
   # @param [String] relative path of the cache contents
-  def load(path)
-    copy (@cache_base + path), path
+  # @param [String] path of where to store it locally, if nil, assume same relative path as the cache contents
+  def load(path, dest = nil)
+    return unless @cache_base
+
+    dest ||= path
+    copy (@cache_base + path), dest
+  end
+
+  def load_without_overwrite(path, dest = nil)
+    return unless @cache_base
+
+    dest ||= path
+
+    case ENV["STACK"]
+    when "heroku-22"
+      copy (@cache_base + path), dest, "-a -n"
+    else
+      copy (@cache_base + path), dest, "-a --update=none"
+    end
   end
 
   # copy cache contents
   # @param [String] source directory
   # @param [String] destination directory
-  def copy(from, to)
+  def copy(from, to, options = "-a")
+    return unless @cache_base
+
     return false unless File.exist?(from)
     FileUtils.mkdir_p File.dirname(to)
-    system("cp -a #{from}/. #{to}")
+    command = "cp #{options} #{from}/. #{to}"
+    system(command)
+    raise "Command failed `#{command}`" unless $?
+  end
+
+  # copy contents between to places in the cache
+  # @param [String] source cache directory
+  # @param [String] destination directory
+  def cache_copy(from, to)
+    return unless @cache_base
+
+    copy(@cache_base + from, @cache_base + to)
   end
 
   # check if the cache content exists
   # @param [String] relative path of the cache contents
   # @param [Boolean] true if the path exists in the cache and false if otherwise
   def exists?(path)
-    File.exists?(@cache_base + path)
+    return unless @cache_base
+
+    File.exist?(@cache_base + path)
   end
 end
diff --git a/lib/language_pack/disable_deploys.rb b/lib/language_pack/disable_deploys.rb
deleted file mode 100644
index 46570bb8d..000000000
--- a/lib/language_pack/disable_deploys.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require "language_pack"
-require "language_pack/base"
-
-class LanguagePack::DisableDeploys < LanguagePack::Base
-  def self.use?
-    File.exist?("Gemfile")
-  end
-
-  def name
-    "Ruby/DisableDeploys"
-  end
-
-  def compile
-    error "Ruby deploys have been temporarily disabled due to a Rubygems.org security breach.\nPlease see https://status.heroku.com/incidents/489 for more info and a workaround if you need to deploy."
-  end
-end
-
diff --git a/lib/language_pack/fetcher.rb b/lib/language_pack/fetcher.rb
index 003096bf3..3f22ec932 100644
--- a/lib/language_pack/fetcher.rb
+++ b/lib/language_pack/fetcher.rb
@@ -3,45 +3,54 @@
 
 module LanguagePack
   class Fetcher
+    class FetchError < StandardError; end
+
     include ShellHelpers
-    CDN_YAML_FILE = File.expand_path("../../../config/cdn.yml", __FILE__)
 
-    def initialize(host_url)
-      @config   = load_config
-      @host_url = fetch_cdn(host_url)
+    def initialize(host_url, stack: nil, arch: nil)
+      @host_url = Pathname.new(host_url)
+      # File.basename prevents accidental directory traversal
+      @host_url += File.basename(stack) if stack
+      @host_url += File.basename(arch) if arch
+    end
+
+    def exists?(path, max_attempts = 1)
+      curl = curl_command("--head #{@host_url.join(path)}")
+      run!(curl, error_class: FetchError, max_attempts: max_attempts, silent: true)
+    rescue FetchError
+      false
     end
 
     def fetch(path)
-      curl = curl_command("-O #{@host_url.join(path)}")
-      run!(curl)
+      curl = curl_command("--remote-name #{@host_url.join(path)}")
+      run!(curl, error_class: FetchError)
     end
 
-    def fetch_untar(path)
-      curl = curl_command("#{@host_url.join(path)} -s -o")
-      run!("#{curl} - | tar zxf -")
+    def fetch_untar(path, files_to_extract = nil, strip_components: 0)
+      curl = curl_command("#{@host_url.join(path)} --no-progress-meter --output")
+      tar_cmd = ["tar", "--strip-components=#{strip_components}", "-xzf", "- #{files_to_extract}"]
+      run! "#{curl} - | #{tar_cmd.join(" ")}",
+        error_class: FetchError,
+        max_attempts: 3
     end
 
-    def fetch_bunzip2(path)
-      curl = curl_command("#{@host_url.join(path)} -s -o")
-      run!("#{curl} - | tar jxf -")
+    def fetch_bunzip2(path, files_to_extract = nil)
+      curl = curl_command("#{@host_url.join(path)} --no-progress-meter --output")
+      run!("#{curl} - | tar jxf - #{files_to_extract}", error_class: FetchError)
     end
 
     private
+
     def curl_command(command)
-      "set -o pipefail; curl --fail --retry 3 --retry-delay 1 --connect-timeout 3 --max-time #{curl_timeout_in_seconds} #{command}"
+      "set -o pipefail; curl --location --fail --retry 5 --retry-delay 1 --connect-timeout #{curl_connect_timeout_in_seconds} --max-time #{curl_timeout_in_seconds} #{command}"
     end
 
     def curl_timeout_in_seconds
-      ENV['CURL_TIMEOUT'] || 30
-    end
-
-    def load_config
-      YAML.load_file(CDN_YAML_FILE) || {}
+      env("CURL_TIMEOUT") || 30
     end
 
-    def fetch_cdn(url)
-      url = @config[url] || url
-      Pathname.new(url)
+    def curl_connect_timeout_in_seconds
+      env("CURL_CONNECT_TIMEOUT") || 3
     end
   end
 end
diff --git a/lib/language_pack/helpers/binstub_check.rb b/lib/language_pack/helpers/binstub_check.rb
new file mode 100644
index 000000000..48ad2e2f0
--- /dev/null
+++ b/lib/language_pack/helpers/binstub_check.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+require "language_pack/helpers/binstub_wrapper"
+# This class is designed to check for binstubs for validity
+#
+# Example:
+#
+#   check = LanguagePack::Helpers::BinstubCheck.new(app_root_dir: Dir.pwd, warn_object: self)
+#   check.call
+class LanguagePack::Helpers::BinstubCheck
+  attr_reader :bad_binstubs
+
+  def initialize(app_root_dir:, warn_object:)
+    @bin_dir = Pathname.new(app_root_dir).join("bin")
+    @warn_object = warn_object
+    @bad_binstubs = []
+  end
+
+  # Checks all binstubs in the directory for a
+  # bad shebang line. If any are present
+  # a warning is created on the passed in `warn_object`
+  def call
+    return unless @bin_dir.directory?
+
+    each_binstub do |binstub|
+      @bad_binstubs << binstub if binstub.bad_shebang?
+    end
+
+    warn unless @bad_binstubs.empty?
+  end
+
+  # Iterates and yields each binstub in a directory
+  # as a BinstubWrapper
+  private def each_binstub
+    @bin_dir.entries.each do |basename|
+      binstub = LanguagePack::Helpers::BinstubWrapper.new(@bin_dir.join(basename))
+
+      next unless binstub.file? # Needed since "." and ".." are returned by Pathname#entries
+      yield binstub
+    end
+  end
+
+  private def warn
+    message = <<~EOM
+      Improperly formatted binstubs detected in your project
+
+      The following file(s) have appear to contain a problematic "shebang" line
+
+      #{@bad_binstubs.map { |binstub| "  - bin/#{binstub.basename}" }.join("\n")}
+
+      For example bin/#{@bad_binstubs.first.basename} has the shebang line:
+
+      ```
+      #{@bad_binstubs.first.open(&:readline).strip}
+      ```
+
+      It should be:
+
+      ```
+      #!/usr/bin/env ruby
+      ```
+
+      A malformed shebang line may cause your program to crash.
+
+      For more information about binstubs and "shebang" lines see:
+        https://devcenter.heroku.com/articles/bad-ruby-binstub-shebang
+    EOM
+
+    @warn_object.warn(message, inline: true)
+  end
+end
diff --git a/lib/language_pack/helpers/binstub_wrapper.rb b/lib/language_pack/helpers/binstub_wrapper.rb
new file mode 100644
index 000000000..93c295219
--- /dev/null
+++ b/lib/language_pack/helpers/binstub_wrapper.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+require "delegate"
+
+# This is a helper class, it wraps a pathname object
+# and adds helper methods used to pull out the first line of the file ("the shebang")
+# as well as determining if the file is binary or not.
+#
+#   binstub = BinstubWrapper.new(Pathname.new(Dir.pwd).join("bin/rails"))
+#   binstub.file? # => true
+#   binstub.binary? #=> false
+#   binstub.bad_shebang? #=> false
+class LanguagePack::Helpers::BinstubWrapper < SimpleDelegator
+  def initialize(string_or_pathname)
+    @binstub = Pathname.new(string_or_pathname)
+    super(@binstub)
+  end
+
+  # Returns false if the shebang line has a ruby binary
+  # that is not simply "ruby" or "ruby.exe"
+  #
+  # Example:
+  #
+  #   bin_dir = Pathname.new(Dir.pwd).join("bin")
+  #   binstub = BinstubWrapper.new(bin_dir.join("rails_good"))
+  #   binstub.shebang # => "#!/usr/bin/env ruby\n"
+  #   binstub.bad_shebang? # => false
+  #
+  #   binstub = BinstubWrapper.new(bin_dir.join("rails_bad"))
+  #   binstub.shebang # => "#!/usr/bin/env ruby2.5\n"
+  #   binstub.bad_shebang? # => true
+  def bad_shebang?
+    return false if binary?
+
+    shebang.match?(/^#!\s*\/usr\/bin\/env\s*ruby(\d.*)$/) # https://rubular.com/r/ozbNEPVInc3sSN
+  end
+
+  # The first line of a binstub contains the "shebang" line
+  # that tells the operating system how to execute the file
+  # for example:
+  #
+  #   binstub = BinstubWrapper.new(Pathname.new(Dir.pwd).join("bin/rails"))
+  #   binstub.shebang # => "#!/usr/bin/env ruby\n"
+  def shebang
+    @shebang ||= begin
+      @binstub.open(&:readline)
+    rescue EOFError
+      +""
+    end
+  end
+
+  # Binary files (may) not have valid UTF-8 encoding. In order to
+  # compare a shebang line, we must first check if the shebang
+  # line is binary or not. To do that, we can see if it is not valid
+  # UTF-8
+  def binary?
+    !valid_utf8?
+  end
+
+  def valid_utf8?
+    shebang.force_encoding("UTF-8").valid_encoding?
+  end
+end
diff --git a/lib/language_pack/helpers/bundle_binstub_check.rb b/lib/language_pack/helpers/bundle_binstub_check.rb
new file mode 100644
index 000000000..5564cacb5
--- /dev/null
+++ b/lib/language_pack/helpers/bundle_binstub_check.rb
@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+# Checks for the presence of a `bin/bundle` binstub in the app.
+#
+# When `bin/bundle` exists, bundler may remove itself during `bundle clean`
+# and then fall back to the default bundler version shipped with Ruby at
+# runtime, which can be a different major version than what the app expects.
+#
+# The fix is to remove the `bin/bundle` binstub from the app.
+#
+# See: https://github.com/heroku/heroku-buildpack-ruby/issues/1690
+# See: https://github.com/ruby/rubygems/issues/9218
+#
+# Example:
+#
+#   check = LanguagePack::Helpers::BundleBinstubCheck.new(
+#     app_root_dir: Dir.pwd,
+#     warn_object: self
+#   )
+#   check.call
+#
+class LanguagePack::Helpers::BundleBinstubCheck
+  def initialize(app_root_dir:, warn_object:)
+    @bin_bundle = Pathname.new(app_root_dir).join("bin", "bundle")
+    @warn_object = warn_object
+  end
+
+  def call
+    if @bin_bundle.exist?
+      @warn_object.warn(warning_message, inline: true)
+    end
+  end
+
+  private def warning_message
+    <<~WARNING
+      Your app has a `bin/bundle` binstub that may cause bundler to
+      malfunction. We recommend you remove it.
+
+      When `bin/bundle` is present, `bundle clean` may remove the
+      installed version of bundler and then your app falls back to
+      the default bundler version that ships with Ruby, which can be
+      a different major version than expected.
+
+      To fix this issue, run:
+
+      ```
+      $ rm bin/bundle
+      $ git add .
+      $ git commit -m "Remove bin/bundle binstub"
+      ```
+
+      For more information see:
+        https://github.com/heroku/heroku-buildpack-ruby/issues/1690
+    WARNING
+  end
+end
diff --git a/lib/language_pack/helpers/bundle_list.rb b/lib/language_pack/helpers/bundle_list.rb
new file mode 100644
index 000000000..43f5f5487
--- /dev/null
+++ b/lib/language_pack/helpers/bundle_list.rb
@@ -0,0 +1,85 @@
+require "language_pack/shell_helpers"
+
+module LanguagePack::Helpers
+  class BundleList
+    class CmdError < BuildpackError
+      def initialize(command:, output:)
+        super(<<~EOF)
+          Error detecting dependencies
+
+          The Ruby buildpack requires information about your application’s dependencies to
+          complete the build. Without this information, the Ruby buildpack cannot continue.
+
+          Command failed: `#{command}`
+
+          #{output}
+        EOF
+      end
+    end
+
+    # Runs `bundle list` and builds a BundleList object
+    # from the output
+    #
+    # Announces the run, optionally streams results to the user.
+    # This is useful for the case where bundler doesn't print
+    # any version info.
+    #
+    # Example:
+    #
+    #    BundleList::Command.new(
+    #      stream_to_user: stream_to_user
+    #    ).call
+    class HumanCommand
+      include LanguagePack::ShellHelpers
+
+      private attr_reader :stream_to_user, :io
+
+      def initialize(stream_to_user:, io: self)
+        @io = io
+        @stream_to_user = stream_to_user
+      end
+
+      def call
+        command = "bundle list"
+        io.puts "Running: #{command}"
+
+        output = if stream_to_user
+          pipe(command, user_env: true, output_object: io)
+        else
+          run(command, user_env: true)
+        end
+
+        if $?.success?
+          BundleList.new(
+            output: output
+          )
+        else
+          raise CmdError.new(output: output, command: command)
+        end
+      end
+    end
+
+    def initialize(output:)
+      @raw = output
+      @gems = {}
+      @raw.scan(/\* (?<name>\S+) \((?<version>[a-zA-Z0-9.]+)(?<git_sha> [a-zA-Z0-9]+)?\)/) do
+        captures = Regexp.last_match.named_captures
+        @gems[captures["name"]] = captures["version"]
+      end
+    end
+
+    def has_gem?(name)
+      @gems[name]
+    end
+
+    def length
+      @gems.length
+    end
+
+    def gem_version(name)
+      if (version = @gems[name])
+        Gem::Version.new(version)
+      end
+    end
+  end
+end
diff --git a/lib/language_pack/helpers/bundler_cache.rb b/lib/language_pack/helpers/bundler_cache.rb
new file mode 100644
index 000000000..a56674b62
--- /dev/null
+++ b/lib/language_pack/helpers/bundler_cache.rb
@@ -0,0 +1,51 @@
+require "pathname"
+require "fileutils"
+require "language_pack/cache"
+
+# manipulating the `vendor/bundle` Bundler cache directory.
+# supports storing the cache in a "stack" directory
+class LanguagePack::BundlerCache
+  attr_reader :bundler_dir
+
+  # @param [LanguagePack::Cache] cache object
+  # @param [String] stack buildpack is running on
+  def initialize(cache, stack = nil)
+    @cache = cache
+    @stack = stack
+    @bundler_dir = Pathname.new("vendor/bundle")
+    @stack_dir = @stack ? Pathname.new(@stack) + @bundler_dir : @bundler_dir
+  end
+
+  # removes the bundler cache dir BOTH in the cache and local directory
+  def clear(stack = nil)
+    stack ||= @stack
+    @cache.clear(stack)
+    @bundler_dir.rmtree
+  end
+
+  # converts to cache directory to support stacks. only copy contents if the stack hasn't changed
+  # @param [Boolean] denote if there's a stack change or not
+  def convert_stack(stack_change)
+    @cache.cache_copy(@bundler_dir, @stack_dir) unless stack_change
+    @cache.clear(@bundler_dir)
+  end
+
+  # detects if using the non stack directory layout
+  def old?
+    @cache.exists?(@bundler_dir)
+  end
+
+  def exists?
+    @cache.exists?(@stack_dir)
+  end
+
+  # writes cache contents to cache store
+  def store
+    @cache.store(@bundler_dir, @stack_dir)
+  end
+
+  # loads cache contents from the cache store
+  def load
+    @cache.load(@stack_dir, @bundler_dir)
+  end
+end
diff --git a/lib/language_pack/helpers/bundler_wrapper.rb b/lib/language_pack/helpers/bundler_wrapper.rb
index c0524d256..e8fbc699f 100644
--- a/lib/language_pack/helpers/bundler_wrapper.rb
+++ b/lib/language_pack/helpers/bundler_wrapper.rb
@@ -1,53 +1,74 @@
+# frozen_string_literal: true
+
+require "json"
+
+# This class is responsible for installing and maintaining a
+# reference to bundler. It contains access to bundler internals
+# that are used to introspect a project such as detecting presence
+# of gems and their versions.
+#
+# Example:
+#
+#   bundler = LanguagePack::Helpers::BundlerWrapper.new(bundler_path: "vendor/bundle/ruby/3.2.0", bundler_version: "2.5.7")
+#   bundler.install
+#   bundler.version                 => "2.5.23"
+#   bundler.dir_name                => "bundler-2.5.23"
+#   bundler.has_gem?("railties")    => true
+#   bundler.gem_version("railties") => "5.2.2"
+#   bundler.clean
+#
+# IMPORTANT: Calling `BundlerWrapper#install` on this class mutates the environment variable
+# ENV['BUNDLE_GEMFILE']. If you're calling in a test context (or anything outside)
+# of an isolated dyno, you must call `BundlerWrapper#clean`. To reset the environment
+# variable:
+#
+#   bundler = LanguagePack::Helpers::BundlerWrapper.new(bundler_path: "vendor/bundle/ruby/3.2.0", bundler_version: "2.5.7")
+#   bundler.install
+#   bundler.clean # <========== IMPORTANT =============
+#
 class LanguagePack::Helpers::BundlerWrapper
-  class GemfileParseError < StandardError
-    def initialize(error)
-      msg = "There was an error parsing your Gemfile, we cannot continue\n"
-      msg << error.message
-      self.set_backtrace(error.backtrace)
-      super msg
-    end
-  end
-
-  VENDOR_URL         = LanguagePack::Base::VENDOR_URL                # coupling
-  DEFAULT_FETCHER    = LanguagePack::Fetcher.new(VENDOR_URL)         # coupling
-  BUNDLER_DIR_NAME   = LanguagePack::Ruby::BUNDLER_GEM_PATH          # coupling
-  BUNDLER_PATH       = File.expand_path("../../../../tmp/#{BUNDLER_DIR_NAME}", __FILE__)
-  GEMFILE_PATH       = Pathname.new "./Gemfile"
-
-  attr_reader   :bundler_path
-
-  def initialize(options = {})
-    @fetcher              = options[:fetcher]      || DEFAULT_FETCHER
-    @bundler_path         = options[:bundler_path] || File.join(Dir.mktmpdir, BUNDLER_DIR_NAME)
-    @gemfile_path         = options[:gemfile_path] || GEMFILE_PATH
-    @bundler_tar          = options[:bundler_tar]  || "#{BUNDLER_DIR_NAME}.tgz"
-    @gemfile_lock_path    = "#{@gemfile_path}.lock"
-    @orig_bundle_gemfile  = ENV['BUNDLE_GEMFILE']
-    ENV['BUNDLE_GEMFILE'] = @gemfile_path.to_s
-    @unlock               = false
-    @path                 = Pathname.new "#{@bundler_path}/gems/#{BUNDLER_DIR_NAME}/lib"
+  include LanguagePack::ShellHelpers
+
+  DEFAULT_VERSION = "2.5.23"
+
+  attr_reader :bundler_path
+
+  def initialize(
+    bundler_path:,
+    bundler_version:,
+    gemfile_path: Pathname.new("./Gemfile"),
+    report: HerokuBuildReport::GLOBAL
+  )
+    @report = report
+    @gemfile_path = gemfile_path
+    @gemfile_lock_path = Pathname.new("#{@gemfile_path}.lock")
+
+    dot_ruby_version_file = @gemfile_lock_path.join("..").join(".ruby-version")
+    @report.capture(
+      "dot_ruby_version.contents" => dot_ruby_version_file.exist? ? dot_ruby_version_file.read&.strip : nil
+    )
+    @version = bundler_version
+    parts = @version.split(".")
+    @report.capture(
+      "bundler.version_installed" => @version,
+      "bundler.major" => parts&.shift,
+      "bundler.minor" => parts&.shift,
+      "bundler.patch" => parts&.shift
+    )
+    @dir_name = "bundler-#{@version}"
+
+    @bundler_path = Pathname(bundler_path)
+    @orig_bundle_gemfile = ENV["BUNDLE_GEMFILE"]
   end
 
   def install
+    ENV["BUNDLE_GEMFILE"] = @gemfile_path.to_s
     fetch_bundler
-    $LOAD_PATH << @path
-    without_warnings do
-      load @path.join("bundler.rb")
-    end
     self
   end
 
   def clean
-    ENV['BUNDLE_GEMFILE'] = @orig_bundle_gemfile
-    FileUtils.remove_entry_secure(bundler_path) if Dir.exist?(bundler_path)
-  end
-
-  def without_warnings(&block)
-    orig_verb  = $VERBOSE
-    $VERBOSE   = nil
-    yield
-  ensure
-    $VERBOSE = orig_verb
+    ENV["BUNDLE_GEMFILE"] = @orig_bundle_gemfile
   end
 
   def has_gem?(name)
@@ -55,80 +76,67 @@ def has_gem?(name)
   end
 
   def gem_version(name)
-    instrument "ruby.gem_version" do
-      if spec = specs[name]
-        spec.version
-      end
-    end
-  end
-
-  # detects whether the Gemfile.lock contains the Windows platform
-  # @return [Boolean] true if the Gemfile.lock was created on Windows
-  def windows_gemfile_lock?
-    platforms.detect do |platform|
-      /mingw|mswin/.match(platform.os) if platform.is_a?(Gem::Platform)
-    end
+    specs[name]
   end
 
   def specs
-    @specs     ||= lockfile_parser.specs.each_with_object({}) {|spec, hash| hash[spec.name] = spec }
+    @specs ||= specs_from_lockfile
   end
 
-  def platforms
-    @platforms ||= lockfile_parser.platforms
-  end
+  attr_reader :version
 
-  def version
-    Bundler::VERSION
-  end
+  attr_reader :dir_name
 
-  def instrument(*args, &block)
-    LanguagePack::Instrument.instrument(*args, &block)
-  end
+  private def fetch_bundler
+    return true if Dir.exist?(bundler_path.join("gems", dir_name))
 
-  def ui
-    Bundler.ui = Bundler::UI::Shell.new({})
-  end
+    topic("Installing bundler #{@version}")
 
-  def definition
-    Bundler.definition(@unlock)
-  rescue => e
-    raise GemfileParseError.new(e)
+    # Install directory structure (as of Bundler 2.1.4):
+    # - cache
+    # - bin
+    # - gems
+    # - specifications
+    # - build_info
+    # - extensions
+    # - doc
+    FileUtils.mkdir_p(bundler_path)
+    run!("GEM_HOME=#{bundler_path} gem install bundler --version #{@version} --no-document --env-shebang")
   end
 
-  def unlock
-    @unlock = true
-    yield
-  ensure
-    @unlock = false
+  # Runs a Ruby subprocess to parse the Gemfile.lock and return specs as a hash.
+  private def specs_from_lockfile
+    LanguagePack::Helpers::LockfileShellParser.call(lockfile_path: @gemfile_lock_path)
   end
 
-  def ruby_version
-    unlock do
-      definition.ruby_version
-    end
-  end
+  def self.resolve_bundler_version(gemfile_lock:, warn_io:)
+    version = gemfile_lock.bundler.version
+    if version
+      version
+    else
+      warn_io.warn(<<~WARNING)
+        Using default bundler version `#{DEFAULT_VERSION}`
 
-  def lockfile_parser
-    @lockfile_parser ||= parse_gemfile_lock
-  end
+        The Ruby buildpack uses the `BUNDLED WITH` value in your `Gemfile.lock` to determine the version
+        of bundler to install. Your `Gemfile.lock` does not contain this section, so a default version
+        of bundler will be installed instead.
 
-  private
-  def fetch_bundler
-    instrument 'fetch_bundler' do
-      return true if Dir.exists?(bundler_path)
-      FileUtils.mkdir_p(bundler_path)
-      Dir.chdir(bundler_path) do
-        @fetcher.fetch_untar(@bundler_tar)
-      end
-      Dir["bin/*"].each {|path| `chmod 755 #{path}` }
-    end
-  end
+        Heroku recommends that you have both a `RUBY VERSION` and `BUNDLED WITH` version listed in your `Gemfile.lock`.
+        You can add it to your project by running:
+
+        ```
+        $ bundle update --bundler
+        ```
+
+        Commit the results to git before redeploying:
+
+        ```
+        $ git add Gemfile.lock
+        $ git commit -m "Add BUNDLED WITH version"
+        ```
+      WARNING
 
-  def parse_gemfile_lock
-    instrument 'parse_bundle' do
-      gemfile_contents = File.read(@gemfile_lock_path)
-      Bundler::LockfileParser.new(gemfile_contents)
+      DEFAULT_VERSION
     end
   end
 end
diff --git a/lib/language_pack/helpers/default_env_vars.rb b/lib/language_pack/helpers/default_env_vars.rb
new file mode 100644
index 000000000..4a2874d4e
--- /dev/null
+++ b/lib/language_pack/helpers/default_env_vars.rb
@@ -0,0 +1,52 @@
+module LanguagePack::Helpers::DefaultEnvVars
+  # Returns a hash of default environment variables for the given inputs
+  #
+  # Values will be written to disk as defaults
+  #
+  # i.e. `export RAILS_ENV=${RAILS_ENV:-production}`
+  #
+  # Therefore it's important that we don't return any values from user provided config vars
+  # or customers will not be able to `heroku config:unset` them.
+  #
+  # @param is_jruby [Boolean] whether the app is using JRuby
+  # @param rack_version [Gem::Version] the version of the rack gem
+  # @param rails_version [Gem::Version] the version of the rails gem
+  # @param secret_key_base [String] the secret key base for the app
+  # @param environment_name [String] the environment name to use for RACK_ENV/RAILS_ENV
+  # @return [Hash] a hash of default environment variables
+  def self.call(is_jruby:, rack_version:, rails_version:, secret_key_base:, environment_name:)
+    out = {}
+    out["LANG"] = "en_US.UTF-8"
+    out["PUMA_PERSISTENT_TIMEOUT"] = "95"
+
+    if is_jruby
+      out["JRUBY_OPTS"] = "-Xcompile.invokedynamic=false"
+    end
+
+    if rack_version
+      out["RACK_ENV"] = environment_name
+    end
+
+    if rails_version
+      out["RAILS_ENV"] = environment_name
+    end
+
+    if rails_version&.>= Gem::Version.new("4.1.0.beta1")
+      if (secret_key_base = secret_key_base&.to_s)
+        out["SECRET_KEY_BASE"] = secret_key_base
+      else
+        raise ArgumentError, "secret_key_base is required for rails 4.1+. Provided: #{secret_key_base.inspect}"
+      end
+    end
+
+    if rails_version&.>= Gem::Version.new("4.2.0")
+      out["RAILS_SERVE_STATIC_FILES"] = "enabled"
+    end
+
+    if rails_version&.>= Gem::Version.new("5.0.0")
+      out["RAILS_LOG_TO_STDOUT"] = "enabled"
+    end
+
+    out
+  end
+end
diff --git a/lib/language_pack/helpers/dot_ruby_version_file.rb b/lib/language_pack/helpers/dot_ruby_version_file.rb
new file mode 100644
index 000000000..29e232f14
--- /dev/null
+++ b/lib/language_pack/helpers/dot_ruby_version_file.rb
@@ -0,0 +1,120 @@
+require "language_pack/shell_helpers"
+require "language_pack/ruby_version"
+
+module LanguagePack
+  module Helpers
+    # Parses contents of `.ruby-version` file to transform it into a RubyVersion
+    #
+    # Example:
+    #
+    #   version = DotRubyVersionFile.new(
+    #     contents: File.read(".ruby-version")
+    #   ).call
+    #   assert_eq [], version.warnings
+    #   assert_eq :ruby, version.ruby_version.engine
+    class DotRubyVersionFile
+      VERSION_PATTERN = /\A(?<version>\d+\.\d+\.\d+)(?:[.-](?<pre>\S+))?\z/
+      JRUBY_PATTERN = /\Ajruby-/i
+      SPECIFIER_PATTERN = /((>|<|~|=)+)/
+
+      Result = Data.define(:ruby_version, :warnings)
+
+      def initialize(contents:)
+        @contents = contents
+      end
+
+      def call
+        warnings = []
+        lines = meaningful_lines
+
+        if lines.empty?
+          return Result.new(ruby_version: nil, warnings: warnings)
+        end
+
+        line = lines.first
+        version_string = strip_ruby_prefix_and_at_suffix(line)
+
+        if lines.length > 1
+          warnings << <<~EOF
+            The `.ruby-version` file contains multiple version lines.
+            Only a single version is supported. Remove additional lines.
+
+            Contents:
+
+            ```
+            #{@contents}
+            ```
+          EOF
+        end
+
+        if version_string.match?(JRUBY_PATTERN)
+          warnings << <<~EOF
+            JRuby not supported in `.ruby-version` file.
+
+            The `.ruby-version` file contains a JRuby version however the
+            JRuby engine is not supported by `.ruby-version` on Heroku at this time.
+
+            Contents:
+
+            ```
+            #{@contents}
+            ```
+          EOF
+        end
+
+        if (match = version_string.match(SPECIFIER_PATTERN))
+          specifier = match[1]
+          warnings << <<~EOF
+            Cannot parse `.ruby-version` file, version specifiers (`#{specifier}`) are not supported.
+
+            Only exact versions are supported such as `3.4.8` or `ruby-3.4.8`.
+            Got:
+
+            ```
+            #{@contents}
+            ```
+          EOF
+        end
+
+        if warnings.any?
+          Result.new(ruby_version: nil, warnings: warnings)
+        elsif (match = version_string.match(VERSION_PATTERN))
+          Result.new(
+            ruby_version: LanguagePack::RubyVersion.new(
+              pre: match[:pre],
+              engine: :ruby,
+              default: false,
+              ruby_version: match[:version],
+              engine_version: match[:version]
+            ),
+            warnings: warnings
+          )
+        else
+          warnings << <<~EOF
+            Cannot parse Ruby version from `.ruby-version` file.
+
+            Only full Ruby versions with major, minor, and patch are supported
+            such as `3.4.8` or `ruby-3.4.8`. Got:
+
+            ```
+            #{@contents}
+            ```
+          EOF
+          Result.new(ruby_version: nil, warnings: warnings)
+        end
+      end
+
+      private def meaningful_lines
+        @contents.gsub(/\s*#.*/, "").each_line.filter_map { |line|
+          stripped = line.strip
+          stripped unless stripped.empty?
+        }
+      end
+
+      private def strip_ruby_prefix_and_at_suffix(line)
+        version = line.delete_prefix("ruby-")
+        version.split("@").first || ""
+      end
+    end
+  end
+end
diff --git a/lib/language_pack/helpers/download_presence.rb b/lib/language_pack/helpers/download_presence.rb
new file mode 100644
index 000000000..749a61579
--- /dev/null
+++ b/lib/language_pack/helpers/download_presence.rb
@@ -0,0 +1,79 @@
+# This class is used to check whether a binary exists on one or more stacks.
+# The main motivation for adding this logic is to help people who are upgrading
+# to a new stack if it does not have a given Ruby version. For example if someone
+# is using Ruby 1.9.3 on the cedar-14 stack then they should be informed that it
+# does not exist if they try to use it on the Heroku-18 stack.
+#
+# Example
+#
+#    download = LanguagePack::Helpers::DownloadPresence.new(
+#      'ruby-3.1.7.tgz',
+#      stacks: ['heroku-22', 'heroku-24', 'heroku-26']
+#    )
+#
+#    download.call
+#
+#    puts download.exists? #=> true
+#    puts download.valid_stack_list #=> ['heroku-22', 'heroku-24', 'heroku-26']
+class LanguagePack::Helpers::DownloadPresence
+  # heroku-22, heroku-24, and heroku-26 have identical ruby versions supported
+  STACKS = ["heroku-22", "heroku-24", "heroku-26"]
+
+  def initialize(file_name:, arch:, amd_only_stacks:, stacks: STACKS)
+    @file_name = file_name
+    @stacks = stacks
+    @fetchers = []
+    @threads = []
+    @stacks.each do |stack|
+      @fetchers << if amd_only_stacks.include?(stack)
+        LanguagePack::Fetcher.new(LanguagePack::Base::VENDOR_URL, stack: stack)
+      else
+        LanguagePack::Fetcher.new(LanguagePack::Base::VENDOR_URL, stack: stack, arch: arch)
+      end
+    end
+  end
+
+  def supported_stack?(current_stack:)
+    @stacks.include?(current_stack)
+  end
+
+  def next_stack(current_stack:)
+    return unless supported_stack?(current_stack: current_stack)
+
+    next_index = @stacks.index(current_stack) + 1
+    @stacks[next_index]
+  end
+
+  def exists_on_next_stack?(current_stack:)
+    return false unless supported_stack?(current_stack: current_stack)
+
+    next_index = @stacks.index(current_stack) + 1
+    @threads[next_index].value
+  end
+
+  def valid_stack_list
+    raise "not invoked yet, use the `call` method first" if @threads.empty?
+
+    @threads.map.with_index do |thread, i|
+      @stacks[i] if thread.value
+    end.compact
+  end
+
+  def exists?
+    raise "not invoked yet, use the `call` method first" if @threads.empty?
+
+    @threads.any? { |t| t.value }
+  end
+
+  def does_not_exist?
+    !exists?
+  end
+
+  def call
+    @fetchers.map do |fetcher|
+      @threads << Thread.new do
+        fetcher.exists?(@file_name, 3)
+      end
+    end
+  end
+end
diff --git a/lib/language_pack/helpers/gemfile_lock.rb b/lib/language_pack/helpers/gemfile_lock.rb
new file mode 100644
index 000000000..c568b974e
--- /dev/null
+++ b/lib/language_pack/helpers/gemfile_lock.rb
@@ -0,0 +1,102 @@
+module LanguagePack
+  module Helpers
+    # Centralize logic for extracting information from the `Gemfile.lock` format
+    #
+    # - Extracts Ruby version from `RUBY VERSION`
+    # - Extracts Bundler version from `BUNDLED WITH`
+    #
+    # Example:
+    #
+    #   gemfile_lock = GemfileLock.new(contents: <<~EOF)
+    #     RUBY VERSION
+    #        ruby 3.3.5p100
+    #     BUNDLED WITH
+    #        2.3.4
+    #   EOF
+    #
+    #   expect(gemfile_lock.bundler.version).to eq("2.3.4")
+    #   expect(gemfile_lock.ruby.ruby_version).to eq("3.3.5")
+    class GemfileLock
+      attr_reader :ruby, :bundler, :contents
+
+      def initialize(contents:, report: HerokuBuildReport::GLOBAL)
+        @ruby = RubyVersionParse.new(contents: contents, report: report)
+        @bundler = BundlerVersionParse.new(contents: contents, report: report)
+        @contents = contents
+      end
+
+      # Holds information about the RUBY VERSION of the parsed Gemfile.lock
+      class RubyVersionParse
+        # Ruby version from Gemfile.lock i.e. `3.3.8`
+        # Either 3 numbers or nil
+        attr_reader :ruby_version,
+          # Contains pre-release info
+          # - String: i.e. "rc2" is a prerelease
+          # - nil: No pre-release (or no version at all)
+          :pre,
+          # Either :ruby or :jruby
+          :engine,
+          # `engine_version` is the JRuby version or for Ruby, it is the same as `ruby_version`
+          # i.e. `<major>.<minor>.<patch>`
+          :engine_version
+
+        def initialize(contents:, report: HerokuBuildReport::GLOBAL)
+          if (match = contents.match(/^RUBY VERSION(?:\r?\n) {2,3}ruby (?<version>\d+\.\d+\.\d+)(?:(?:-|\.)(?<pre>\S*))?/m))
+            @pre = match[:pre]
+            @empty = false
+            @ruby_version = match[:version]
+          else
+            if contents.match?(/RUBY VERSION/)
+              report.capture("gemfile_lock.ruby_version.failed_parse" => true)
+              if (match = contents.match(/(?<contents>RUBY VERSION(?:\r?\n).*)$/))
+                report.capture("gemfile_lock.ruby_version.failed_contents" => match[:contents])
+              end
+            end
+            @pre = nil
+            @empty = true
+            @ruby_version = nil
+          end
+
+          if (jruby = contents.to_s.match(/^RUBY VERSION(?:\r?\n) {2,3}ruby [^(]*\(jruby (?<version>(?:\d+|\.)+)\)/m))
+            @engine = :jruby
+            @engine_version = jruby[:version]
+          else
+            @engine = :ruby
+            @engine_version = ruby_version
+          end
+        end
+
+        def empty?
+          @empty
+        end
+      end
+
+      class BundlerVersionParse
+        # Bundler value from `Gemfile.lock` (String or nil) i.e. `2.5.23`
+        attr_reader :version
+
+        def initialize(contents:, report: HerokuBuildReport::GLOBAL)
+          if (match = contents.match(/^BUNDLED WITH(?:\r?\n) {2,3}(?<version>(?<major>\d+)\.(?<minor>\d+)\.\d+)/m))
+            @empty = false
+            @version = match[:version]
+          else
+            if contents.match?(/BUNDLED WITH/)
+              report.capture("gemfile_lock.bundler_version.failed_parse" => true)
+              if (match = contents.match(/(?<contents>BUNDLED WITH(?:\r?\n).*)$/))
+                report.capture("gemfile_lock.bundler_version.failed_contents" => match[:contents])
+              end
+            end
+            @empty = true
+            @version = nil
+          end
+
+          report.capture("gemfile_lock.bundled_with.empty" => @empty)
+        end
+
+        def empty?
+          @empty
+        end
+      end
+    end
+  end
+end
diff --git a/lib/language_pack/helpers/lockfile_shell_parser.rb b/lib/language_pack/helpers/lockfile_shell_parser.rb
new file mode 100644
index 000000000..c6f964252
--- /dev/null
+++ b/lib/language_pack/helpers/lockfile_shell_parser.rb
@@ -0,0 +1,78 @@
+# frozen_string_literal: true
+
+require "json"
+require "tempfile"
+require "open3"
+
+module LanguagePack
+  module Helpers
+    # Parses gem specs from a Gemfile.lock file using Bundler::LockfileParser.
+    #
+    # This module encapsulates the logic for extracting gem names and versions
+    # from a lockfile, running the parsing in a subprocess to avoid polluting
+    # the current process's Bundler state.
+    #
+    # This can be called before gems are installed (but after Ruby and Bundler are installed).
+    # The output of this and `bundle list` (which can only be invoked after gems are installed)
+    # will disagree based on env vars such as `BUNDLE_WITHOUT`.
+    #
+    # This output will usually be a superset of `bundle list` output.
+    #
+    # Example:
+    #
+    #   specs = LockfileShellParser.call(lockfile_path: "/path/to/Gemfile.lock")
+    #   specs["rake"] # => #<Gem::Version "13.2.1">
+    #
+    module LockfileShellParser
+      RUBY_PARSER_CODE = <<~RUBY
+        require "json"
+        require "bundler"
+
+        specs = Bundler::LockfileParser.new(STDIN.read)
+          .specs
+          .each_with_object({}) {|spec, hash| hash[spec.name.to_s] = spec.version.to_s }
+        puts specs.to_json
+      RUBY
+
+      # Parses gem specs from a Gemfile.lock file path.
+      #
+      # @param lockfile_path [String, Pathname] Path to the Gemfile.lock file
+      # @return [Hash{String => Gem::Version}] Hash of gem names to their versions
+      #
+      # Example:
+      #
+      #   specs = LockfileShellParser.call(lockfile_path: "Gemfile.lock")
+      #   specs["rails"]    # => #<Gem::Version "7.0.4">
+      #   specs["nokogiri"] # => #<Gem::Version "1.15.0">
+      #
+      def self.call(lockfile_path:)
+        lockfile_path = Pathname(lockfile_path)
+        Tempfile.create(["lockfile_parser", ".rb"]) do |tempfile|
+          tempfile.write(RUBY_PARSER_CODE)
+          tempfile.flush
+
+          stdout, stderr, status = Open3.capture3("ruby", tempfile.path, stdin_data: lockfile_path.read(mode: "rt"))
+          if status.success?
+            JSON.parse(stdout).transform_values { |version| Gem::Version.new(version) }
+          else
+            raise <<~ERROR
+              Cannot parse `Gemfile.lock` file at path `#{lockfile_path}`
+
+              The Ruby buildpack runs a Ruby script that uses Bundler::LockfileParser to parse the lockfile of your application.
+              This information is needed to set environment variables based on requested gems such as `RAILS_ENV`
+              before gems are installed via `bundle install`.
+
+              This script failed to parse `#{lockfile_path}` and the buildpack cannot continue.
+
+              Debugging information:
+
+              status: #{status}
+              stdout: #{stdout}
+              stderr: #{stderr}
+            ERROR
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/language_pack/helpers/node_installer.rb b/lib/language_pack/helpers/node_installer.rb
new file mode 100644
index 000000000..27724eb63
--- /dev/null
+++ b/lib/language_pack/helpers/node_installer.rb
@@ -0,0 +1,30 @@
+class LanguagePack::Helpers::NodeInstaller
+  attr_reader :version
+
+  def initialize(arch:)
+    nodebin = LanguagePack::Helpers::Nodebin.node_lts(arch: arch)
+    @version = nodebin["number"]
+    @url = nodebin["url"]
+    @fetcher = LanguagePack::Fetcher.new("")
+  end
+
+  def binary_path
+    File.basename(@url).delete_suffix(".tar.gz")
+  end
+
+  def install
+    # Untar of this file produces artifacts that the app does not need to run.
+    # If we ran this command in the app directory, we would have to manually
+    # clean up un-used files. Instead we untar in a temp directory which
+    # helps us avoid accidentally deleting code out of the user's slug by mistake.
+    Dir.mktmpdir do |dir|
+      node_bin = "#{binary_path}/bin/node"
+
+      Dir.chdir(dir) do
+        @fetcher.fetch_untar(@url, node_bin)
+      end
+
+      FileUtils.mv("#{dir}/#{node_bin}", ".")
+    end
+  end
+end
diff --git a/lib/language_pack/helpers/nodebin.rb b/lib/language_pack/helpers/nodebin.rb
new file mode 100644
index 000000000..9156a1a98
--- /dev/null
+++ b/lib/language_pack/helpers/nodebin.rb
@@ -0,0 +1,29 @@
+require "json"
+
+class LanguagePack::Helpers::Nodebin
+  NODE_VERSION = "24.13.0"
+  YARN_VERSION = "1.22.22"
+
+  def self.hardcoded_node_lts(arch:)
+    arch = "x64" if arch == "amd64"
+    {
+      "number" => NODE_VERSION,
+      "url" => "https://nodejs.org/download/release/v#{NODE_VERSION}/node-v#{NODE_VERSION}-linux-#{arch}.tar.gz"
+    }
+  end
+
+  def self.hardcoded_yarn
+    {
+      "number" => YARN_VERSION,
+      "url" => "https://registry.npmjs.org/yarn/-/yarn-#{YARN_VERSION}.tgz"
+    }
+  end
+
+  def self.node_lts(arch:)
+    hardcoded_node_lts(arch: arch)
+  end
+
+  def self.yarn
+    hardcoded_yarn
+  end
+end
diff --git a/lib/language_pack/helpers/outdated_ruby_version.rb b/lib/language_pack/helpers/outdated_ruby_version.rb
new file mode 100644
index 000000000..82641e3e7
--- /dev/null
+++ b/lib/language_pack/helpers/outdated_ruby_version.rb
@@ -0,0 +1,182 @@
+# Queries S3 in the background to determine
+# what versions are supported so they can be recommended
+# to the user
+#
+# Example:
+#
+#   ruby_version = LanguagePack::RubyVersion.from_gemfile_lock(ruby: gemfile_lock.ruby)
+#   outdated = LanguagePack::Helpers::OutdatedRubyVersion.new(
+#     current_ruby_version: ruby_version,
+#     fetcher: LanguagePack::Fetcher.new(LanguagePack::Base::VENDOR_URL, stack: "heroku-22")
+#     fetcher: LanguagePack::Fetcher.new(LanguagePack::Base::VENDOR_URL, stack: "heroku-22", arch: "amd64")
+#   )
+#
+#   outdated.call
+#   puts outdated.suggested_ruby_minor_version
+#   #=> "ruby-2.2.10"
+class LanguagePack::Helpers::OutdatedRubyVersion
+  DEFAULT_RANGE = 1..5
+  attr_reader :current_ruby_version
+
+  def initialize(current_ruby_version:, fetcher:)
+    @current_ruby_version = current_ruby_version
+    @fetcher = fetcher
+    @already_joined = false
+
+    @minor_versions = []
+    @eol_versions = []
+
+    @minor_version_threads = []
+    @eol_version_threads = []
+
+    @suggested_eol_version = nil
+    @suggested_minor_version = nil
+  end
+
+  def can_check?
+    return false if current_ruby_version.jruby?
+
+    true
+  end
+
+  # Enqueues checks in the background
+  def call
+    return self unless can_check?
+    raise "Cannot `call()` twice" unless @minor_version_threads.empty?
+
+    check_minor_versions
+    check_eol_versions_major
+    check_eol_versions_minor
+    self
+  end
+
+  def join
+    return unless can_check?
+    return true if @already_joined
+    raise "Must initalize threads with `call()` before joining" if @minor_version_threads.empty?
+
+    @eol_versions = @eol_version_threads.map(&:value).compact
+    @minor_versions = @minor_version_threads.map(&:value).compact
+    @minor_versions << current_ruby_version.ruby_version
+
+    @suggested_minor_version = @minor_versions
+      .map { |v| v.sub("ruby-", "") }
+      .max_by { |v| Gem::Version.new(v) }
+
+    @suggested_eol_version = @eol_versions
+      .map { |v| v.sub("ruby-", "") }
+      .sort_by { |v| Gem::Version.new(v) }
+      .last(3)
+      .first
+
+    @already_joined = true
+  end
+
+  def suggested_ruby_minor_version
+    join
+    @suggested_minor_version
+  end
+
+  def latest_minor_version?
+    join
+    @suggested_minor_version == current_ruby_version.ruby_version
+  end
+
+  def eol?
+    join
+
+    @eol_versions.length > 3
+  end
+
+  # Account for preview releases
+  def maybe_eol?
+    join
+
+    @eol_versions.length > 2
+  end
+
+  def suggest_ruby_eol_version
+    return false unless maybe_eol?
+    @suggested_eol_version
+      .sub(/0$/, "x")
+  end
+
+  # Checks for a range of "tiny" versions in parallel
+  #
+  # For example if 2.5.0 is given it will check for the existance of
+  # - 2.5.1
+  # - 2.5.2
+  # - 2.5.3
+  # - 2.5.4
+  # - 2.5.5
+  #
+  # If the last elment in the series exists, it will continue to
+  # search by enqueuing additional numbers until the final
+  # value in the series is found
+  private def check_minor_versions(range: DEFAULT_RANGE, base_version: current_ruby_version, &block)
+    range.each do |i|
+      @minor_version_threads << Thread.new do
+        version = base_version.next_logical_version(i)
+        next if !@fetcher.exists?("#{version}.tgz")
+
+        if i == range.last
+          check_minor_versions(
+            range: Range.new(i + 1, i + i),
+            base_version: base_version
+          )
+        end
+
+        version
+      end
+    end
+  end
+
+  # Checks to see if 3 minor versions exist above current version
+  #
+  # for example 2.4.0 would check for existance of:
+  #   - 2.5.0
+  #   - 2.6.0
+  #   - 2.7.0
+  #   - 2.8.0
+  private def check_eol_versions_minor(range: DEFAULT_RANGE, base_version: current_ruby_version)
+    range.each do |i|
+      @eol_version_threads << Thread.new do
+        version = base_version.next_minor_version(i)
+
+        next if !@fetcher.exists?("#{version}.tgz")
+
+        if i == range.last
+          check_eol_versions_minor(
+            range: Range.new(i + 1, i + i),
+            base_version: base_version
+          )
+        end
+
+        version
+      end
+    end
+  end
+
+  # Checks to see if one major version exists above current version
+  # if it does, then it will check for minor versions of that version
+  #
+  # For checking 2.5. it would check for the existance of 3.0.0
+  #
+  # If 3.0.0 exists then it will check for:
+  #   - 3.1.0
+  #   - 3.2.0
+  #   - 3.3.0
+  private def check_eol_versions_major
+    @eol_version_threads << Thread.new do
+      version = current_ruby_version.next_major_version(1)
+
+      next if !@fetcher.exists?("#{version}.tgz")
+
+      check_eol_versions_minor(
+        base_version: LanguagePack::RubyVersion.default(last_version: version)
+      )
+
+      version
+    end
+  end
+end
diff --git a/lib/language_pack/helpers/plugin_installer.rb b/lib/language_pack/helpers/plugin_installer.rb
index 7c659b00a..bc4d4f5b4 100644
--- a/lib/language_pack/helpers/plugin_installer.rb
+++ b/lib/language_pack/helpers/plugin_installer.rb
@@ -9,7 +9,7 @@ class PluginsInstaller
       include LanguagePack::ShellHelpers
 
       def initialize(plugins, vendor_url = LanguagePack::Base::VENDOR_URL)
-        @plugins    = plugins || []
+        @plugins = plugins || []
         @vendor_url = vendor_url
       end
 
@@ -30,9 +30,13 @@ def vendor(name)
         return true if directory.exist?
         directory.mkpath
         Dir.chdir(directory) do |dir|
-          run("curl #{vendor_url}/#{name}.tgz -s -o - | tar xzf -")
+          run("curl #{vendor_url}/#{name}.tgz --no-progress-meter --fail --retry 3 --retry-connrefused --connect-timeout #{curl_connect_timeout_in_seconds} --output - | tar xzf -")
         end
       end
+
+      def curl_connect_timeout_in_seconds
+        env("CURL_CONNECT_TIMEOUT") || 3
+      end
     end
   end
 end
diff --git a/lib/language_pack/helpers/puma_warn_error.rb b/lib/language_pack/helpers/puma_warn_error.rb
new file mode 100644
index 000000000..017ec6b48
--- /dev/null
+++ b/lib/language_pack/helpers/puma_warn_error.rb
@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+# Checks for Puma specific warnings and errors
+class LanguagePack::Helpers::PumaWarnError
+  attr_reader :warnings, :error, :puma_version
+
+  def initialize(puma_version:, env:)
+    @warnings = []
+    @error = nil
+    @env = env
+    @puma_version = puma_version
+
+    warn_router_2_0_compatibility
+    error_persistent_timeout
+  end
+
+  private def warn_router_2_0_compatibility
+    return if @puma_version >= Gem::Version.new("7.0.3")
+    warnings << <<~WARNING
+      Heroku recommends using Puma 7.0.3+ for compatibility with Router 2.0
+
+      Please upgrade your application to Puma 7.0.3+ by running the following commands:
+
+      ```
+      $ gem install puma
+      $ bundle update puma
+      $ git add Gemfile.lock && git commit -m "Upgrade Puma to 7.0.3+"
+      ```
+    WARNING
+  end
+
+  private def error_persistent_timeout
+    return if @puma_version >= Gem::Version.new("7.0.3")
+    return if @puma_version < Gem::Version.new("7.0.0")
+    # If they manually set it, it is likely being used in their `config/puma.rb` file
+    return if @env["PUMA_PERSISTENT_TIMEOUT"]
+
+    @error = <<~ERROR
+      Your application is using Puma #{puma_version}.
+
+      This has a known issue with the `PUMA_PERSISTENT_TIMEOUT` environment variable.
+
+      This is fixed in Puma 7.0.3+ via https://github.com/puma/puma/pull/3749.
+      Please upgrade your application to Puma 7.0.3+ by running the following commands:
+
+      ```
+      $ gem install puma
+      $ bundle update puma
+      $ git add Gemfile.lock && git commit -m "Upgrade Puma to 7.0.3+"
+      ```
+    ERROR
+  end
+end
diff --git a/lib/language_pack/helpers/rails_runner.rb b/lib/language_pack/helpers/rails_runner.rb
new file mode 100644
index 000000000..a24092635
--- /dev/null
+++ b/lib/language_pack/helpers/rails_runner.rb
@@ -0,0 +1,138 @@
+# frozen_string_literal: true
+
+# This class is used for running `rails runner` against
+# apps, primarially for the intention of detecting configuration.
+#
+# The main benefit of this class is that multiple config
+# queries can be grouped together so the application only
+# has to be booted once. Calling `did_match` on a
+# RailsConfig object will trigger the `rails runner` command
+# to be executed.
+#
+# Example usage:
+#
+#    rails_config   = RailsRunner.new
+#    local_storage  = rails_config.detect("active_storage.service")
+#    assets_compile = rails_config.detect("assets.compile")
+#
+#    local_storage.success?             # => true
+#    local_storage.did_match?("local")  # => false
+#
+#    assets_compile.success?            # => true
+#    assets_compile.did_match?("false") # => true
+#
+class LanguagePack::Helpers::RailsRunner
+  # This class is used to help pull configuration values
+  # from a rails application. It takes in a configuration key
+  # and a reference to the parent RailsRunner object which
+  # allows it obtain the `rails runner` output and success
+  # status of the operation.
+  #
+  # For example:
+  #
+  #    config = RailsConfig.new("active_storage.service", rails_runner)
+  #    config.to_command # => "puts %Q{heroku.detecting.config.for.active_storage.service=Rails.application.config.try(:active_storage).try(:service)}; "
+  #
+  class RailsConfig
+    def initialize(config, rails_runner, options = {})
+      @config = config
+      @rails_runner = rails_runner
+      @debug = options[:debug]
+
+      @success = nil
+      @did_time_out = false
+      @heroku_key = "heroku.detecting.config.for.#{config}"
+
+      @rails_config = +'#{'
+      @rails_config << "Rails.application.config"
+      config.split(".").each do |part|
+        @rails_config << ".try(:#{part})"
+      end
+      @rails_config << "}"
+    end
+
+    def success?
+      @rails_runner.success? && @rails_runner.output =~ %r{#{@heroku_key}}
+    end
+
+    def did_match?(val)
+      @rails_runner.output =~ %r{#{@heroku_key}=#{val}}
+    end
+
+    def to_command
+      cmd = +"begin; "
+      cmd << "puts %Q{"
+      cmd << "#{@heroku_key}=#{@rails_config}"
+      cmd << "}; "
+      cmd << "rescue => e; "
+      cmd << "puts e; puts e.backtrace; " if @debug
+      cmd << "end;"
+      cmd
+    end
+  end
+
+  include LanguagePack::ShellHelpers
+
+  def initialize(debug = env("HEROKU_DEBUG_RAILS_RUNNER"), timeout = 65)
+    @command_array = []
+    @output = nil
+    @success = false
+    @debug = debug
+    @timeout_val = timeout # seconds
+  end
+
+  def detect(config_string)
+    config = RailsConfig.new(config_string, self, debug: @debug)
+    @command_array << config.to_command
+    config
+  end
+
+  def output
+    @output ||= call
+  end
+
+  def success?
+    output && @success
+  end
+
+  def command
+    %(rails runner "#{@command_array.join(" ")}")
+  end
+
+  def timeout?
+    @did_time_out
+  end
+
+  private
+
+  def call
+    topic("Detecting rails configuration")
+    puts "$ #{command}" if @debug
+    out = execute_command!
+    puts out if @debug
+    out
+  end
+
+  def execute_command!
+    process = ProcessSpawn.new(command,
+      user_env: true,
+      timeout: @timeout_val,
+      file: "./.heroku/ruby/config_detect/rails.txt")
+
+    @success = process.success?
+    @did_time_out = process.timeout?
+    out = process.output
+
+    if timeout?
+      message = +"Detecting rails configuration timeout\n"
+      message << "set HEROKU_DEBUG_RAILS_RUNNER=1 to debug" unless @debug
+      warn(message)
+    elsif !@success
+      message = +"Detecting rails configuration failed\n"
+      message << "set HEROKU_DEBUG_RAILS_RUNNER=1 to debug" unless @debug
+      warn(message)
+    end
+
+    out
+  end
+end
diff --git a/lib/language_pack/helpers/rake_runner.rb b/lib/language_pack/helpers/rake_runner.rb
index 84b9b2d40..82d2cdac3 100644
--- a/lib/language_pack/helpers/rake_runner.rb
+++ b/lib/language_pack/helpers/rake_runner.rb
@@ -1,21 +1,29 @@
 class LanguagePack::Helpers::RakeRunner
   include LanguagePack::ShellHelpers
 
+  class CannotLoadRakefileError < StandardError
+  end
+
   class RakeTask
     ALLOWED = [:pass, :fail, :no_load, :not_found]
     include LanguagePack::ShellHelpers
 
-    attr_accessor :output, :time, :task, :status, :task_defined, :rakefile_can_load
+    attr_accessor :output, :time, :task, :task_defined, :rakefile_can_load
+    attr_writer :status
 
-    alias :rakefile_can_load? :rakefile_can_load
-    alias :task_defined?      :task_defined
-    alias :is_defined?        :task_defined
+    alias_method :rakefile_can_load?, :rakefile_can_load
+    alias_method :task_defined?, :task_defined
+    alias_method :is_defined?, :task_defined
 
     def initialize(task, options = {})
-      @task            = task
+      @task = task
       @default_options = {user_env: true}.merge(options)
-      @status          = :nil
-      @output          = ""
+      @status = :nil
+      @output = ""
+    end
+
+    def not_defined?
+      !is_defined?
     end
 
     def success?
@@ -26,41 +34,39 @@ def status?
       @status && @status != :nil
     end
 
+    # Is set by RakeTask#invoke to one of the ALLOWED verbs
     def status
-      raise "Status not set for #{self.inspect}" if @status == :nil
-      raise "Not allowed status: #{@status} for #{self.inspect}" unless ALLOWED.include?(@status)
+      raise "Status not set for #{inspect}" if @status == :nil
+      raise "Not allowed status: #{@status} for #{inspect}" unless ALLOWED.include?(@status)
       @status
     end
 
     def invoke(options = {})
-      options      = @default_options.merge(options)
+      options = @default_options.merge(options)
       quiet_option = options.delete(:quiet)
 
       puts "Running: rake #{task}" unless quiet_option
       time = Benchmark.realtime do
-        cmd = "rake #{task}"
-
-        if quiet_option
-          self.output = run("rake #{task}", options)
+        self.output = if quiet_option
+          run("rake #{task}", options)
         else
-          self.output = pipe("rake #{task}", options)
+          pipe("rake #{task}", options)
         end
       end
       self.time = time
 
-      if $?.success?
-        self.status = :pass
+      self.status = if $?.success?
+        :pass
       else
-        self.status = :fail
+        :fail
       end
-      return self
+      self
     end
   end
 
-  def initialize(has_rake_gem = true)
-    @has_rake = has_rake_gem && has_rakefile?
-    if !@has_rake
-      @rake_tasks    = ""
+  def initialize
+    if !has_rake_installed?
+      @rake_tasks = ""
       @rakefile_can_load = false
     end
   end
@@ -73,33 +79,32 @@ def rakefile_can_load?
     @rakefile_can_load
   end
 
-  def instrument(*args, &block)
-    LanguagePack::Instrument.instrument(*args, &block)
+  def load_rake_tasks(options = {})
+    @rake_tasks ||= RakeTask.new("-P --trace").invoke(options.merge(quiet: true)).output
+    @rakefile_can_load ||= $?.success?
+    @rake_tasks
   end
 
-  def load_rake_tasks(options = {})
-    instrument "ruby.rake_task_defined" do
-      @rake_tasks        ||= RakeTask.new("-P --trace").invoke(options.merge(quiet: true)).output
-      @rakefile_can_load ||= $?.success?
-      @rake_tasks
+  def load_rake_tasks!(options = {}, raise_on_fail = false)
+    return if !has_rake_installed?
+
+    out = load_rake_tasks(options)
+
+    if cannot_load_rakefile?
+      msg = "Could not detect rake tasks\n"
+      msg << "ensure you can run `$ bundle exec rake -P` against your app\n"
+      msg << "and using the production group of your Gemfile.\n"
+      msg << out
+      raise CannotLoadRakefileError, msg if raise_on_fail
+      puts msg
     end
-  end
 
-  def load_rake_tasks!(options = {})
-    out =  load_rake_tasks(options)
-    msg =  "Could not detect rake tasks\n"
-    msg << "ensure you can run `$ bundle exec rake -P` against your app with no environment variables present\n"
-    msg << "and using the production group of your Gemfile.\n"
-    msg << "This may be intentional, if you expected rake tasks to be run\n"
-    msg << "cancel the build (CTRL+C) and fix the error then commit the fix:\n"
-    msg << out
-    puts msg if cannot_load_rakefile?
-    return self
+    self
   end
 
   def task_defined?(task)
     return false if cannot_load_rakefile?
-    @task_available ||= Hash.new {|hash, key| hash[key] = @rake_tasks.match(/\s#{key}\s/) }
+    @task_available ||= Hash.new { |hash, key| hash[key] = @rake_tasks.match(/\s#{key}\s/) }
     @task_available[task]
   end
 
@@ -109,7 +114,7 @@ def not_found?(task)
 
   def task(rake_task, options = {})
     t = RakeTask.new(rake_task, options)
-    t.task_defined      = task_defined?(rake_task)
+    t.task_defined = task_defined?(rake_task)
     t.rakefile_can_load = rakefile_can_load?
     t
   end
@@ -118,9 +123,11 @@ def invoke(task, options = {})
     self.task(task, options).invoke
   end
 
-private
+  def has_rake_installed?
+    @has_rake ||= has_rakefile?
+  end
 
-  def has_rakefile?
-    %W{ Rakefile rakefile  rakefile.rb Rakefile.rb}.detect {|file| File.exist?(file) }
+  private def has_rakefile?
+    %W[Rakefile rakefile rakefile.rb Rakefile.rb].detect { |file| File.exist?(file) }
   end
 end
diff --git a/lib/language_pack/helpers/stale_file_cleaner.rb b/lib/language_pack/helpers/stale_file_cleaner.rb
index 1f7d82658..a740e8da9 100644
--- a/lib/language_pack/helpers/stale_file_cleaner.rb
+++ b/lib/language_pack/helpers/stale_file_cleaner.rb
@@ -1,13 +1,13 @@
 class LanguagePack::Helpers::StaleFileCleaner
-  FILE_STAT_CACHE = Hash.new {|h, k| h[k] = File.stat(k) }
+  FILE_STAT_CACHE = Hash.new { |h, k| h[k] = File.stat(k) }
 
   def initialize(dir)
-    @dir  = dir
+    @dir = dir
     raise "need or dir" if @dir.nil?
   end
 
   def clean_over(limit) # limit in bytes
-    old_files_over(limit).each {|asset| FileUtils.rm(asset) }
+    old_files_over(limit).each { |asset| FileUtils.rm(asset) }
   end
 
   def glob
@@ -15,20 +15,19 @@ def glob
   end
 
   def files
-    @files ||= Dir[glob].reject {|file| File.directory?(file) }
+    @files ||= Dir[glob].reject { |file| File.directory?(file) }
   end
 
   def sorted_files
-    @sorted ||= files.sort_by {|a| FILE_STAT_CACHE[a].mtime }
+    @sorted ||= files.sort_by { |a| FILE_STAT_CACHE[a].mtime }
   end
 
   def total_size
-    @size   ||= sorted_files.inject(0) {|sum, asset| sum += FILE_STAT_CACHE[asset].size }
+    @size ||= sorted_files.inject(0) { |sum, asset| sum + FILE_STAT_CACHE[asset].size }
   end
 
-
   def old_files_over(limit)
     diff = total_size - limit
-    sorted_files.take_while {|asset| diff -= FILE_STAT_CACHE[asset].size if diff > 0 } || []
+    sorted_files.take_while { |asset| diff -= FILE_STAT_CACHE[asset].size if diff > 0 } || []
   end
 end
diff --git a/lib/language_pack/helpers/yarn_installer.rb b/lib/language_pack/helpers/yarn_installer.rb
new file mode 100644
index 000000000..e83b4c30c
--- /dev/null
+++ b/lib/language_pack/helpers/yarn_installer.rb
@@ -0,0 +1,30 @@
+class LanguagePack::Helpers::YarnInstaller
+  attr_reader :version
+
+  def initialize
+    # Grab latest yarn, until release practice stabilizes
+    # https://github.com/yarnpkg/yarn/issues/376#issuecomment-253366910
+    nodebin = LanguagePack::Helpers::Nodebin.yarn
+    @version = nodebin["number"]
+    @url = nodebin["url"]
+    @fetcher = LanguagePack::Fetcher.new("")
+  end
+
+  def name
+    "yarn-v#{@version}"
+  end
+
+  def binary_path
+    "#{name}/bin/"
+  end
+
+  def install
+    Dir.mktmpdir do |dir|
+      Dir.chdir(dir) do
+        @fetcher.fetch_untar(@url, strip_components: 1)
+      end
+
+      FileUtils.cp_r(dir, name)
+    end
+  end
+end
diff --git a/lib/language_pack/installers/heroku_ruby_installer.rb b/lib/language_pack/installers/heroku_ruby_installer.rb
new file mode 100644
index 000000000..9add9c886
--- /dev/null
+++ b/lib/language_pack/installers/heroku_ruby_installer.rb
@@ -0,0 +1,109 @@
+require "language_pack/base"
+require "language_pack/shell_helpers"
+
+module LanguagePack::Installers; end
+
+class LanguagePack::Installers::HerokuRubyInstaller
+  BASE_URL = LanguagePack::Base::VENDOR_URL
+
+  include LanguagePack::ShellHelpers
+
+  attr_reader :fetcher, :environment
+
+  def initialize(stack:, amd_only_stacks:, arch:, app_path:, env:, report: HerokuBuildReport::GLOBAL)
+    @report = report
+    @environment = env
+    @app_path = Pathname.new(app_path).expand_path
+    @fetcher = self.class.fetcher(amd_only_stacks: amd_only_stacks, stack: stack, arch: arch)
+  end
+
+  def self.fetcher(amd_only_stacks:, stack:, arch:)
+    if amd_only_stacks.include?(stack)
+      LanguagePack::Fetcher.new(BASE_URL, stack: stack)
+    else
+      LanguagePack::Fetcher.new(BASE_URL, stack: stack, arch: arch)
+    end
+  end
+
+  def install(ruby_version, install_dir)
+    install_dir = Pathname.new(install_dir).expand_path
+    @report.capture(
+      # i.e. `jruby` or `ruby`
+      "ruby_version_engine" => ruby_version.engine,
+      # i.e. `ruby-3.4.2-jruby-10.0.2.0` or `ruby-3.4.2` or `ruby-3.5.0.pre1`
+      "ruby_version_unique" => ruby_version.version_for_download,
+      # i.e. `default` or `Gemfile.lock`
+      "ruby_version_origin" => ruby_version.default? ? "default" : "Gemfile.lock"
+    )
+
+    case ruby_version.engine
+    when :ruby
+      @report.capture(
+        "ruby_version_major_minor" => "#{ruby_version.major}.#{ruby_version.minor}",
+        "ruby_version_full" => ruby_version.engine_version_full
+      )
+    when :jruby
+      @report.capture(
+        # i.e. `3.4.2` the target spec ruby version
+        "jruby_version_ruby_version" => ruby_version.ruby_version,
+        # i.e. `10.0.2.0` the version of jruby
+        "jruby_version_full" => ruby_version.engine_version_full,
+        # i.e. `9.4` or `10.0`
+        "jruby_version_major_minor" => [
+          ruby_version.engine_version.split(".")[0],
+          ruby_version.engine_version.split(".")[1]
+        ].join(".")
+      )
+    else
+      raise "Internal error: Unknown engine: #{ruby_version.engine}"
+    end
+
+    fetch_unpack(ruby_version, install_dir)
+    setup_binstubs(install_dir)
+
+    if ruby_version.jruby?
+      environment["JRUBY_OPTS"] = environment["JRUBY_BUILD_OPTS"] ||
+        user_env_hash["JRUBY_BUILD_OPTS"] ||
+        environment["JRUBY_OPTS"] ||
+        user_env_hash["JRUBY_OPTS"]
+    end
+    # Ruby binstub path
+    environment["PATH"] = [install_dir.join("bin"), environment["PATH"]].compact.join(":")
+  end
+
+  def fetch_unpack(ruby_version, install_dir)
+    FileUtils.mkdir_p(install_dir)
+    Dir.chdir(install_dir) do
+      @fetcher.fetch_untar("#{ruby_version.version_for_download}.tgz")
+    end
+  end
+
+  private def setup_binstubs(install_dir)
+    bin_dir = @app_path.join("bin")
+    bin_dir.mkpath
+    run("ln -s ruby #{install_dir}/bin/ruby.exe")
+
+    Dir["#{install_dir}/bin/*"].each do |vendor_bin|
+      # for Ruby 2.6.0+ don't symlink the Bundler bin so our shim works
+      next if vendor_bin.include?("bundle")
+
+      # The bin/rake binstub generated when compiling ruby does not load bundler
+      # which can cause unexpected failures. Deleting this binstub allows two things:
+      #
+      #   - If the app includes a custom binstub allows it to be used
+      #   - If the app does not include a custom binstub, then it will fall back to vendor/bundle/bin/rake
+      #     which is generated by bundler
+      #
+      # Discussion: https://github.com/heroku/heroku-buildpack-ruby/issues/1025#issuecomment-653102430
+      next if vendor_bin.include?("rake")
+
+      # Calculate relative path from bin_dir to vendor_bin so symlinks work
+      # at runtime when the app moves from /tmp/build_xxx to /app
+      vendor_bin_path = Pathname.new(vendor_bin).expand_path
+      relative_path = vendor_bin_path.relative_path_from(bin_dir)
+      bin_name = File.basename(vendor_bin)
+
+      run("ln -s #{relative_path} #{bin_dir.join(bin_name)}")
+    end
+  end
+end
diff --git a/lib/language_pack/instrument.rb b/lib/language_pack/instrument.rb
deleted file mode 100644
index ccc7397ef..000000000
--- a/lib/language_pack/instrument.rb
+++ /dev/null
@@ -1,69 +0,0 @@
-require 'benchmark'
-require 'stringio'
-require 'lpxc'
-require 'date'
-require 'language_pack/ruby'
-
-module LanguagePack
-  module Instrument
-    def self.bench_msg(message, level = 0, start_time, end_time, duration, build_id, buildpack_version)
-      out.puts "measure.#{message}.start=#{start_time} measure.#{message}.end=#{end_time} measure.#{message}.duration=#{duration} measure.#{message}.level=#{level} measure.#{message}.build_id=#{build_id} request_id=#{request_id} measure.#{message}.buildpack_version=#{buildpack_version} measure.#{message}.buildpack=#{buildpack_name} "
-    end
-
-    def self.instrument(cat, title = "", *args)
-      ret        = nil
-      start_time = DateTime.now.iso8601(6)
-      duration = Benchmark.realtime do
-        yield_with_block_depth do
-          ret = yield
-        end
-      end
-      end_time   = DateTime.now.iso8601(6)
-      bench_msg(cat, block_depth, start_time, end_time, duration, build_id, buildpack_version)
-
-      ret
-    end
-
-    def self.out
-      Thread.current[:out] ||= ENV['LOGPLEX_DEFAULT_TOKEN'] ? Lpxc.new(batch_size: 1) : StringIO.new
-    end
-
-    def self.trace(name, *args, &blk)
-      ret         = nil
-      block_depth = 0
-
-      instrument(name) { blk.call }
-    end
-
-    def self.yield_with_block_depth
-      self.block_depth += 1
-      yield
-    ensure
-      self.block_depth -= 1
-    end
-
-    def self.block_depth
-      Thread.current[:block_depth] || 0
-    end
-
-    def self.block_depth=(value)
-      Thread.current[:block_depth] = value
-    end
-
-    def self.build_id
-      ENV['REQUEST_ID'] || ENV['SLUG_ID']
-    end
-
-    def self.request_id
-      ENV['REQUEST_ID']
-    end
-
-    def self.buildpack_version
-      LanguagePack::Ruby::BUILDPACK_VERSION
-    end
-
-    def self.buildpack_name
-      LanguagePack::Ruby::NAME
-    end
-  end
-end
diff --git a/lib/language_pack/metadata.rb b/lib/language_pack/metadata.rb
index 3694159a6..ad98e9793 100644
--- a/lib/language_pack/metadata.rb
+++ b/lib/language_pack/metadata.rb
@@ -1,35 +1,49 @@
 require "language_pack"
 require "language_pack/base"
 
+# Store data about the build in the cache
+#
+# Uses `<cache_path>/vendor/heroku` as the metadata directory. Which
+# is special cased in cache clearing code to be durable. This allows
+# for persistant generated data such as SECRET_KEY_BASE that would otherwise
+# cause session invalidation if it changed unexpectedly between deploys.
 class LanguagePack::Metadata
-  FOLDER = "vendor/heroku"
+  def initialize(cache_path:)
+    @dir = Pathname(cache_path)
+      .join("vendor")
+      .join("heroku")
+      .tap(&:mkpath)
+  end
+
+  def empty?
+    @dir.children.empty?
+  end
 
-  def initialize(cache)
-    if cache
-      @cache = cache
-      @cache.load FOLDER
+  def try_read(key)
+    if exists?(key)
+      read(key)
     end
   end
 
   def read(key)
-    full_key = "#{FOLDER}/#{key}"
-    File.read(full_key) if exists?(key)
+    @dir.join(key).read&.strip
   end
-  
+
   def exists?(key)
-    full_key = "#{FOLDER}/#{key}"
-    File.exists?(full_key) && !Dir.exists?(full_key)
+    @dir.join(key).file?
   end
 
-  def write(key, value, isave = true)
-    FileUtils.mkdir_p(FOLDER)
-
-    full_key = "#{FOLDER}/#{key}"
-    File.open(full_key, 'w') {|f| f.puts value }
-    save if isave
+  def write(key, value)
+    @dir.join(key).write(value)
   end
 
-  def save
-    @cache ? @cache.store(FOLDER) : false
+  def fetch(key)
+    if exists?(key)
+      read(key)
+    else
+      value = yield
+      write(key, value.to_s)
+      value
+    end
   end
 end
diff --git a/lib/language_pack/no_lockfile.rb b/lib/language_pack/no_lockfile.rb
deleted file mode 100644
index 7a52af279..000000000
--- a/lib/language_pack/no_lockfile.rb
+++ /dev/null
@@ -1,16 +0,0 @@
-require "language_pack"
-require "language_pack/base"
-
-class LanguagePack::NoLockfile < LanguagePack::Base
-  def self.use?
-    !File.exists?("Gemfile.lock")
-  end
-
-  def name
-    "Ruby/NoLockfile"
-  end
-
-  def compile
-    error "Gemfile.lock required. Please check it in."
-  end
-end
diff --git a/lib/language_pack/rack.rb b/lib/language_pack/rack.rb
index 19ef59f09..eb973a30d 100644
--- a/lib/language_pack/rack.rb
+++ b/lib/language_pack/rack.rb
@@ -3,47 +3,24 @@
 
 # Rack Language Pack. This is for any non-Rails Rack apps like Sinatra.
 class LanguagePack::Rack < LanguagePack::Ruby
-
   # detects if this is a valid Rack app by seeing if "config.ru" exists
   # @return [Boolean] true if it's a Rack app
-  def self.use?
-    instrument "rack.use" do
-      bundler.gem_version('rack')
-    end
+  def self.use?(bundler:)
+    bundler.gem_version("rack")
   end
 
   def name
     "Ruby/Rack"
   end
 
-  def default_config_vars
-    instrument "rack.default_config_vars" do
-      super.merge({
-        "RACK_ENV" => "production"
-      })
-    end
-  end
-
   def default_process_types
-    instrument "rack.default_process_types" do
-      # let's special case thin here if we detect it
-      web_process = bundler.has_gem?("thin") ?
-        "bundle exec thin start -R config.ru -e $RACK_ENV -p $PORT" :
-        "bundle exec rackup config.ru -p $PORT"
-
-      super.merge({
-        "web" => web_process
-      })
-    end
+    # let's special case thin here if we detect it
+    web_process = bundler.has_gem?("thin") ?
+      "bundle exec thin start -R config.ru -e $RACK_ENV -p ${PORT:-5000}" :
+      "bundle exec rackup config.ru -p ${PORT:-5000}"
+
+    super.merge({
+      "web" => web_process
+    })
   end
-
-private
-
-  # sets up the profile.d script for this buildpack
-  def setup_profiled
-    super
-    set_env_default "RACK_ENV", "production"
-  end
-
 end
-
diff --git a/lib/language_pack/rails2.rb b/lib/language_pack/rails2.rb
index 64b0f62e8..0b3b84759 100644
--- a/lib/language_pack/rails2.rb
+++ b/lib/language_pack/rails2.rb
@@ -6,71 +6,59 @@
 class LanguagePack::Rails2 < LanguagePack::Ruby
   # detects if this is a valid Rails 2 app
   # @return [Boolean] true if it's a Rails 2 app
-  def self.use?
-    instrument "rails2.use" do
-      rails_version = bundler.gem_version('rails')
-      return false unless rails_version
-      is_rails2 = rails_version >= Gem::Version.new('2.0.0') &&
-                  rails_version <  Gem::Version.new('3.0.0')
-      return is_rails2
-    end
+  def self.use?(bundler:)
+    rails_version = bundler.gem_version("rails")
+    return false unless rails_version
+    rails_version >= Gem::Version.new("2.0.0") &&
+      rails_version < Gem::Version.new("3.0.0")
   end
 
-  def name
-    "Ruby/Rails"
+  def initialize(...)
+    super
+    @rails_runner = LanguagePack::Helpers::RailsRunner.new
   end
 
-  def default_config_vars
-    instrument "rails2.default_config_vars" do
-      super.merge({
-        "RAILS_ENV" => "production",
-        "RACK_ENV" => "production"
-      })
-    end
+  def name
+    "Ruby/Rails"
   end
 
   def default_process_types
-    instrument "rails2.default_process_types" do
-      web_process = bundler.has_gem?("thin") ?
-        "bundle exec thin start -e $RAILS_ENV -p $PORT" :
-        "bundle exec ruby script/server -p $PORT"
+    web_process = bundler.has_gem?("thin") ?
+      "bundle exec thin start -e $RAILS_ENV -p ${PORT:-5000}" :
+      "bundle exec ruby script/server -p ${PORT:-5000}"
 
-      super.merge({
-        "web" => web_process,
-        "worker" => "bundle exec rake jobs:work",
-        "console" => "bundle exec script/console"
-      })
-    end
+    process_types = super
+    process_types["web"] = web_process
+    process_types["worker"] = "bundle exec rake jobs:work" if has_jobs_work_task?
+    process_types["console"] = "bundle exec script/console"
+    process_types
   end
 
   def compile
-    instrument "rails2.compile" do
-      install_plugins
-      super
-    end
+    install_plugins
+    super
   end
 
-private
-
-  def install_plugins
-    instrument "rails2.install_plugins" do
-      plugins = ["rails_log_stdout"].reject { |plugin| bundler.has_gem?(plugin) }
-      topic "Rails plugin injection"
-      LanguagePack::Helpers::PluginsInstaller.new(plugins).install
+  def best_practice_warnings
+    if env("RAILS_ENV") != "production"
+      warn(<<~WARNING)
+        You are deploying to a non-production environment: #{env("RAILS_ENV").inspect}.
+        This is not recommended.
+        See https://devcenter.heroku.com/articles/deploying-to-a-custom-rails-environment for more information.
+      WARNING
     end
+    super
   end
 
-  # most rails apps need a database
-  # @return [Array] shared database addon
-  def add_dev_database_addon
-    ['heroku-postgresql:hobby-dev']
-  end
+  private
 
-  # sets up the profile.d script for this buildpack
-  def setup_profiled
-    super
-    set_env_default "RACK_ENV",  "production"
-    set_env_default "RAILS_ENV", "production"
+  def has_jobs_work_task?
+    rake.task("jobs:work").is_defined?
   end
 
+  def install_plugins
+    plugins = ["rails_log_stdout"].reject { |plugin| bundler.has_gem?(plugin) }
+    topic "Rails plugin injection"
+    LanguagePack::Helpers::PluginsInstaller.new(plugins).install
+  end
 end
diff --git a/lib/language_pack/rails3.rb b/lib/language_pack/rails3.rb
index 685a438f7..4cdcb3eb7 100644
--- a/lib/language_pack/rails3.rb
+++ b/lib/language_pack/rails3.rb
@@ -5,14 +5,11 @@
 class LanguagePack::Rails3 < LanguagePack::Rails2
   # detects if this is a Rails 3.x app
   # @return [Boolean] true if it's a Rails 3.x app
-  def self.use?
-    instrument "rails3.use" do
-      rails_version = bundler.gem_version('railties')
-      return false unless rails_version
-      is_rails3 = rails_version >= Gem::Version.new('3.0.0') &&
-                  rails_version <  Gem::Version.new('4.0.0')
-      return is_rails3
-    end
+  def self.use?(bundler:)
+    rails_version = bundler.gem_version("railties")
+    return false unless rails_version
+    rails_version >= Gem::Version.new("3.0.0") &&
+      rails_version < Gem::Version.new("4.0.0")
   end
 
   def name
@@ -20,93 +17,181 @@ def name
   end
 
   def default_process_types
-    instrument "rails3.default_process_types" do
-      # let's special case thin here
-      web_process = bundler.has_gem?("thin") ?
-        "bundle exec thin start -R config.ru -e $RAILS_ENV -p $PORT" :
-        "bundle exec rails server -p $PORT"
-
-      super.merge({
-        "web" => web_process,
-        "console" => "bundle exec rails console"
-      })
-    end
+    # let's special case thin here
+    web_process = bundler.has_gem?("thin") ?
+      "bundle exec thin start -R config.ru -e $RAILS_ENV -p ${PORT:-5000}" :
+      "bundle exec rails server -p ${PORT:-5000}"
+
+    super.merge({
+      "web" => web_process,
+      "console" => "bundle exec rails console"
+    })
+  end
+
+  def rake_env
+    {
+      "RAILS_ENV" => @environment_name,
+      "RACK_ENV" => @environment_name,
+      "RAILS_GROUPS" => "assets"
+    }.merge(super)
   end
 
   def compile
-    instrument "rails3.compile" do
-      super
+    super
+  end
+
+  def config_detect
+    super
+    @assets_compile_config = @rails_runner.detect("assets.compile")
+    @x_sendfile_config = @rails_runner.detect("action_dispatch.x_sendfile_header")
+  end
+
+  def best_practice_warnings
+    super
+    warn_x_sendfile_use!
+
+    if assets_compile_enabled?
+      safe_sprockets_version_needed = sprocket_version_upgrade_needed
+      if safe_sprockets_version_needed
+        message = <<~ERROR
+          A security vulnerability has been detected in your application.
+          To protect your application you must take action. Your application
+          is currently exposing its credentials via an easy to exploit directory
+          traversal.
+          
+          To protect your application you must either upgrade to Sprockets version "#{safe_sprockets_version_needed}"
+          or disable dynamic compilation at runtime by setting:
+          
+          ```
+          config.assets.compile = false # Disables security vulnerability
+          ```
+          
+          To read more about this security vulnerability please refer to this blog post:
+            https://blog.heroku.com/rails-asset-pipeline-vulnerability
+          
+        ERROR
+        error(message)
+      end
+
+      warn(<<~WARNING)
+        You set your `config.assets.compile = true` in production.
+        This can negatively impact the performance of your application.
+
+        For more information can be found in this article:
+          https://devcenter.heroku.com/articles/rails-asset-pipeline#compile-set-to-true-in-production
+
+      WARNING
+    end
+  end
+
+  private
+
+  def warn_x_sendfile_use!
+    return false unless @x_sendfile_config.success?
+    if @x_sendfile_config.did_match?("X-Sendfile") && !has_apache? # Apache
+      warn(<<~WARNING)
+        You set `config.action_dispatch.x_sendfile_header = 'X-Sendfile'` in production,
+        but you do not have `apache` installed on this app. This setting will cause any assets
+        being served by your application to be returned without a body.
+
+        To fix this issue, please set:
+
+        ```
+        config.action_dispatch.x_sendfile_header = nil
+        ```
+      WARNING
     end
+
+    if @x_sendfile_config.did_match?("X-Accel-Redirect") && !has_nginx? # Nginx
+      warn(<<~WARNING)
+        You set `config.action_dispatch.x_sendfile_header = 'X-Accel-Redirect'` in production,
+        but you do not have `nginx` installed on this app. This setting will cause any assets
+        being served by your application to be returned without a body.
+
+        To fix this issue, please set:
+
+        ```
+        config.action_dispatch.x_sendfile_header = nil
+        ```
+      WARNING
+    end
+  end
+
+  def has_apache?
+    path = run("command -v apachectl")
+    return true if path && $?.success?
+    false
   end
 
-private
+  def has_nginx?
+    path = run("command -v nginx")
+    return true if path && $?.success?
+    false
+  end
+
+  def sprocket_version_upgrade_needed
+    # Due to https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-3760
+    sprockets_version = bundler.gem_version("sprockets")
+    if sprockets_version.nil?
+      false
+    elsif sprockets_version < Gem::Version.new("2.12.5")
+      "2.12.5"
+    elsif sprockets_version > Gem::Version.new("3") &&
+        sprockets_version < Gem::Version.new("3.7.2")
+      "3.7.2"
+    elsif sprockets_version > Gem::Version.new("4") &&
+        sprockets_version < Gem::Version.new("4.0.0.beta8")
+      "4.0.0.beta8"
+    else
+      false
+    end
+  end
+
+  def assets_compile_enabled?
+    return false unless @assets_compile_config.success?
+    @assets_compile_config.did_match?("true")
+  end
 
   def install_plugins
-    instrument "rails3.install_plugins" do
-      return false if bundler.has_gem?('rails_12factor')
-      plugins = {"rails_log_stdout" => "rails_stdout_logging", "rails3_serve_static_assets" => "rails_serve_static_assets" }.
-                 reject { |plugin, gem| bundler.has_gem?(gem) }
-      return false if plugins.empty?
-      plugins.each do |plugin, gem|
-        warn "Injecting plugin '#{plugin}'"
-      end
-      warn "Add 'rails_12factor' gem to your Gemfile to skip plugin injection"
-      LanguagePack::Helpers::PluginsInstaller.new(plugins.keys).install
+    return false if bundler.has_gem?("rails_12factor")
+    plugins = {"rails_log_stdout" => "rails_stdout_logging", "rails3_serve_static_assets" => "rails_serve_static_assets"}
+      .reject { |plugin, gem| bundler.has_gem?(gem) }
+    return false if plugins.empty?
+    plugins.each do |plugin, gem|
+      warn "Injecting plugin '#{plugin}'"
     end
+    warn "Add 'rails_12factor' gem to your Gemfile to skip plugin injection"
+    LanguagePack::Helpers::PluginsInstaller.new(plugins.keys).install
   end
 
   # runs the tasks for the Rails 3.1 asset pipeline
   def run_assets_precompile_rake_task
-    instrument "rails3.run_assets_precompile_rake_task" do
-      log("assets_precompile") do
-        if File.exists?("public/assets/manifest.yml")
-          puts "Detected manifest.yml, assuming assets were compiled locally"
-          return true
-        end
-
-        precompile = rake.task("assets:precompile")
-        return true unless precompile.is_defined?
-
-        topic("Preparing app for Rails asset pipeline")
-
-        precompile.invoke(env: rake_env)
-
-        if precompile.success?
-          log "assets_precompile", :status => "success"
-          puts "Asset precompilation completed (#{"%.2f" % precompile.time}s)"
-        else
-          log "assets_precompile", :status => "failure"
-          error "Precompiling assets failed."
-        end
-      end
+    if File.exist?("public/assets/manifest.yml")
+      puts "Detected manifest.yml, assuming assets were compiled locally"
+      return true
     end
-  end
 
-  def rake_env
-    if user_env_hash.empty?
-      default_env = {
-        "RAILS_GROUPS" => ENV["RAILS_GROUPS"] || "assets",
-        "RAILS_ENV"    => ENV["RAILS_ENV"]    || "production",
-        "DATABASE_URL" => database_url
-      }
+    precompile = rake.task("assets:precompile")
+    return true unless precompile.is_defined?
+
+    topic("Preparing app for Rails asset pipeline")
+
+    precompile.invoke(env: rake_env)
+
+    if precompile.success?
+      puts "Asset precompilation completed (#{"%.2f" % precompile.time}s)"
     else
-      default_env = {
-        "RAILS_GROUPS" => "assets",
-        "RAILS_ENV"    => "production",
-        "DATABASE_URL" => database_url
-      }
+      precompile_fail(precompile.output)
     end
-    default_env.merge(user_env_hash)
   end
 
   # generate a dummy database_url
   def database_url
-    instrument "rails3.setup_database_url_env" do
-      # need to use a dummy DATABASE_URL here, so rails can load the environment
-      return env("DATABASE_URL") if env("DATABASE_URL")
-      scheme =
-        if bundler.has_gem?("pg") || bundler.has_gem?("jdbc-postgres")
-          "postgres"
+    # need to use a dummy DATABASE_URL here, so rails can load the environment
+    return env("DATABASE_URL") if env("DATABASE_URL")
+    scheme =
+      if bundler.has_gem?("pg") || bundler.has_gem?("jdbc-postgres")
+        "postgres"
       elsif bundler.has_gem?("mysql")
         "mysql"
       elsif bundler.has_gem?("mysql2")
@@ -114,6 +199,8 @@ def database_url
       elsif bundler.has_gem?("sqlite3") || bundler.has_gem?("sqlite3-ruby")
         "sqlite3"
       end
+
+    if scheme
       "#{scheme}://user:pass@127.0.0.1/dbname"
     end
   end
diff --git a/lib/language_pack/rails4.rb b/lib/language_pack/rails4.rb
index 04626b633..7b019fd91 100644
--- a/lib/language_pack/rails4.rb
+++ b/lib/language_pack/rails4.rb
@@ -7,14 +7,11 @@ class LanguagePack::Rails4 < LanguagePack::Rails3
 
   # detects if this is a Rails 4.x app
   # @return [Boolean] true if it's a Rails 4.x app
-  def self.use?
-    instrument "rails4.use" do
-      rails_version = bundler.gem_version('railties')
-      return false unless rails_version
-      is_rails4 = rails_version >= Gem::Version.new('4.0.0.beta') &&
-                  rails_version <  Gem::Version.new('4.1.0.beta1')
-      return is_rails4
-    end
+  def self.use?(bundler:)
+    rails_version = bundler.gem_version("railties")
+    return false unless rails_version
+    rails_version >= Gem::Version.new("4.0.0.beta") &&
+      rails_version < Gem::Version.new("5.x")
   end
 
   def name
@@ -22,40 +19,28 @@ def name
   end
 
   def default_process_types
-    instrument "rails4.default_process_types" do
-      super.merge({
-        "web"     => "bin/rails server -p $PORT -e $RAILS_ENV",
-        "console" => "bin/rails console"
-      })
-    end
-  end
-
-  def build_bundler
-    instrument "rails4.build_bundler" do
-      super
-    end
+    super.merge({
+      "web" => "bin/rails server -p ${PORT:-5000} -e $RAILS_ENV",
+      "console" => "bin/rails console"
+    })
   end
 
   def compile
-    instrument "rails4.compile" do
-      super
-    end
+    super
   end
 
   private
 
   def install_plugins
-    instrument "rails4.install_plugins" do
-      return false if bundler.has_gem?('rails_12factor')
-      plugins = ["rails_serve_static_assets", "rails_stdout_logging"].reject { |plugin| bundler.has_gem?(plugin) }
-      return false if plugins.empty?
-
-    warn <<-WARNING
-Include 'rails_12factor' gem to enable all platform features
-See https://devcenter.heroku.com/articles/rails-integration-gems for more information.
-WARNING
+    return false if bundler.has_gem?("rails_12factor")
+    plugins = ["rails_serve_static_assets", "rails_stdout_logging"].reject { |plugin| bundler.has_gem?(plugin) }
+    return false if plugins.empty?
+
+    warn <<~WARNING
+      Include 'rails_12factor' gem to enable all platform features
+      See https://devcenter.heroku.com/articles/rails-integration-gems for more information.
+    WARNING
     # do not install plugins, do not call super
-    end
   end
 
   def public_assets_folder
@@ -66,45 +51,47 @@ def default_assets_cache
     "tmp/cache/assets"
   end
 
+  def cleanup
+    super
+    return if assets_compile_enabled?
+    return unless Dir.exist?(default_assets_cache)
+    FileUtils.remove_dir(default_assets_cache)
+  end
+
   def run_assets_precompile_rake_task
-    instrument "rails4.run_assets_precompile_rake_task" do
-      log("assets_precompile") do
-        if Dir.glob('public/assets/manifest-*.json').any?
-          puts "Detected manifest file, assuming assets were compiled locally"
-          return true
-        end
+    if Dir.glob("public/assets/{.sprockets-manifest-*.json,manifest-*.json}", File::FNM_DOTMATCH).any?
+      puts "Detected manifest file, assuming assets were compiled locally"
+      return true
+    end
 
-        precompile = rake.task("assets:precompile")
-        return true unless precompile.is_defined?
+    precompile = rake.task("assets:precompile")
+    return true if precompile.not_defined?
 
-        topic("Preparing app for Rails asset pipeline")
+    topic("Preparing app for Rails asset pipeline")
 
-        @cache.load public_assets_folder
-        @cache.load default_assets_cache
+    @cache.load_without_overwrite public_assets_folder
+    @cache.load default_assets_cache
 
-        precompile.invoke(env: rake_env)
+    precompile.invoke(env: rake_env)
 
-        if precompile.success?
-          log "assets_precompile", :status => "success"
-          puts "Asset precompilation completed (#{"%.2f" % precompile.time}s)"
+    if precompile.success?
+      puts "Asset precompilation completed (#{"%.2f" % precompile.time}s)"
 
-          puts "Cleaning assets"
-          rake.task("assets:clean").invoke(env: rake_env)
+      clean_task = rake.task("assets:clean")
+      if clean_task.task_defined?
+        puts "Cleaning assets"
+        clean_task.invoke(env: rake_env)
 
-          cleanup_assets_cache
-          @cache.store public_assets_folder
-          @cache.store default_assets_cache
-        else
-          log "assets_precompile", :status => "failure"
-          error "Precompiling assets failed."
-        end
+        cleanup_assets_cache
+        @cache.store public_assets_folder
+        @cache.store default_assets_cache
       end
+    else
+      precompile_fail(precompile.output)
     end
   end
 
   def cleanup_assets_cache
-    instrument "rails4.cleanup_assets_cache" do
-      LanguagePack::Helpers::StaleFileCleaner.new(default_assets_cache).clean_over(ASSETS_CACHE_LIMIT)
-    end
+    LanguagePack::Helpers::StaleFileCleaner.new(default_assets_cache).clean_over(ASSETS_CACHE_LIMIT)
   end
 end
diff --git a/lib/language_pack/rails41.rb b/lib/language_pack/rails41.rb
deleted file mode 100644
index 924924a4b..000000000
--- a/lib/language_pack/rails41.rb
+++ /dev/null
@@ -1,51 +0,0 @@
-require 'securerandom'
-require "language_pack"
-require "language_pack/rails4"
-
-class LanguagePack::Rails41 < LanguagePack::Rails4
-  # detects if this is a Rails 4.x app
-  # @return [Boolean] true if it's a Rails 4.x app
-  def self.use?
-    instrument "rails4.use" do
-      rails_version = bundler.gem_version('railties')
-      return false unless rails_version
-      is_rails4 = rails_version >= Gem::Version.new('4.1.0.beta1') &&
-                  rails_version <  Gem::Version.new('5.0.0')
-      return is_rails4
-    end
-  end
-
-  def create_database_yml
-    instrument 'ruby.create_database_yml' do
-    end
-  end
-
-  def setup_profiled
-    instrument 'setup_profiled' do
-      super
-      set_env_default "SECRET_KEY_BASE", app_secret
-    end
-  end
-
-  def default_config_vars
-    super.merge({
-      "SECRET_KEY_BASE" => app_secret
-    })
-  end
-
-  private
-  def app_secret
-    key = "secret_key_base"
-
-    @app_secret ||= begin
-      if @metadata.exists?(key)
-        @metadata.read(key).chomp
-      else
-        secret = SecureRandom.hex(64)
-        @metadata.write(key, secret)
-
-        secret
-      end
-    end
-  end
-end
diff --git a/lib/language_pack/rails5.rb b/lib/language_pack/rails5.rb
new file mode 100644
index 000000000..cee936e39
--- /dev/null
+++ b/lib/language_pack/rails5.rb
@@ -0,0 +1,16 @@
+require "securerandom"
+require "language_pack"
+
+class LanguagePack::Rails5 < LanguagePack::Rails4
+  # @return [Boolean] true if it's a Rails 5.x app
+  def self.use?(bundler:)
+    rails_version = bundler.gem_version("railties")
+    return false unless rails_version
+    rails_version >= Gem::Version.new("5.x") &&
+      rails_version < Gem::Version.new("6.0.0")
+  end
+
+  def install_plugins
+    # do not install plugins, do not call super, do not warn
+  end
+end
diff --git a/lib/language_pack/rails6.rb b/lib/language_pack/rails6.rb
new file mode 100644
index 000000000..5ab4e9a45
--- /dev/null
+++ b/lib/language_pack/rails6.rb
@@ -0,0 +1,18 @@
+require "securerandom"
+require "language_pack"
+require "language_pack/rails5"
+
+class LanguagePack::Rails6 < LanguagePack::Rails5
+  # @return [Boolean] true if it's a Rails 6.x app
+  def self.use?(bundler:)
+    rails_version = bundler.gem_version("railties")
+    return false unless rails_version
+    rails_version >= Gem::Version.new("6.x") &&
+      rails_version < Gem::Version.new("7.a")
+  end
+
+  def compile
+    FileUtils.mkdir_p("tmp/pids")
+    super
+  end
+end
diff --git a/lib/language_pack/rails7.rb b/lib/language_pack/rails7.rb
new file mode 100644
index 000000000..ec8a23448
--- /dev/null
+++ b/lib/language_pack/rails7.rb
@@ -0,0 +1,13 @@
+require "securerandom"
+require "language_pack"
+require "language_pack/rails6"
+
+class LanguagePack::Rails7 < LanguagePack::Rails6
+  # @return [Boolean] true if it's a Rails 7.x app
+  def self.use?(bundler:)
+    rails_version = bundler.gem_version("railties")
+    return false unless rails_version
+    rails_version >= Gem::Version.new("7.a") &&
+      rails_version < Gem::Version.new("8.a")
+  end
+end
diff --git a/lib/language_pack/rails8.rb b/lib/language_pack/rails8.rb
new file mode 100644
index 000000000..8f1606f4c
--- /dev/null
+++ b/lib/language_pack/rails8.rb
@@ -0,0 +1,13 @@
+require "securerandom"
+require "language_pack"
+require "language_pack/rails7"
+
+class LanguagePack::Rails8 < LanguagePack::Rails7
+  # @return [Boolean] true if it's a Rails 8.x app
+  def self.use?(bundler:)
+    rails_version = bundler.gem_version("railties")
+    return false unless rails_version
+    rails_version >= Gem::Version.new("8.a") &&
+      rails_version < Gem::Version.new("9.a")
+  end
+end
diff --git a/lib/language_pack/ruby.rb b/lib/language_pack/ruby.rb
index 3615252bc..ed080380d 100644
--- a/lib/language_pack/ruby.rb
+++ b/lib/language_pack/ruby.rb
@@ -5,43 +5,28 @@
 require "language_pack"
 require "language_pack/base"
 require "language_pack/ruby_version"
+require "language_pack/helpers/nodebin"
+require "language_pack/helpers/node_installer"
+require "language_pack/helpers/yarn_installer"
+require "language_pack/helpers/binstub_check"
+require "language_pack/helpers/bundle_binstub_check"
 require "language_pack/version"
 
 # base Ruby Language Pack. This is for any base ruby app.
 class LanguagePack::Ruby < LanguagePack::Base
-  NAME                 = "ruby"
-  LIBYAML_VERSION      = "0.1.5"
-  LIBYAML_PATH         = "libyaml-#{LIBYAML_VERSION}"
-  BUNDLER_VERSION      = "1.5.2"
-  BUNDLER_GEM_PATH     = "bundler-#{BUNDLER_VERSION}"
-  NODE_VERSION         = "0.4.7"
-  NODE_JS_BINARY_PATH  = "node-#{NODE_VERSION}"
-  JVM_BASE_URL         = "http://heroku-jdk.s3.amazonaws.com"
-  LATEST_JVM_VERSION   = "openjdk7-latest"
-  LEGACY_JVM_VERSION   = "openjdk1.7.0_25"
-  DEFAULT_RUBY_VERSION = "ruby-2.0.0"
-  RBX_BASE_URL         = "http://binaries.rubini.us/heroku"
+  NAME = "ruby"
+  NODE_BP_PATH = "vendor/node/bin"
 
   # detects if this is a valid Ruby app
   # @return [Boolean] true if it's a Ruby app
-  def self.use?
-    instrument "ruby.use" do
-      File.exist?("Gemfile")
-    end
-  end
-
-  def self.bundler
-    @bundler ||= LanguagePack::Helpers::BundlerWrapper.new.install
-  end
-
-  def bundler
-    self.class.bundler
+  def self.use?(bundler: nil)
+    File.exist?("Gemfile")
   end
 
-  def initialize(build_path, cache_path=nil)
-    super(build_path, cache_path)
-    @fetchers[:jvm] = LanguagePack::Fetcher.new(JVM_BASE_URL)
-    @fetchers[:rbx] = LanguagePack::Fetcher.new(RBX_BASE_URL)
+  def initialize(...)
+    super
+    @node_installer = LanguagePack::Helpers::NodeInstaller.new(arch: @arch)
+    @yarn_installer = LanguagePack::Helpers::YarnInstaller.new
   end
 
   def name
@@ -49,142 +34,255 @@ def name
   end
 
   def default_addons
-    instrument "ruby.default_addons" do
-      add_dev_database_addon
-    end
+    add_dev_database_addon
   end
 
-  def default_config_vars
-    instrument "ruby.default_config_vars" do
-      vars = {
-        "LANG"     => "en_US.UTF-8",
-      }
-
-      ruby_version.jruby? ? vars.merge({
-        "JAVA_OPTS" => default_java_opts,
-        "JRUBY_OPTS" => default_jruby_opts,
-        "JAVA_TOOL_OPTIONS" => default_java_tool_options
-      }) : vars
+  # Environment variable defaults that are passed to ENV, `export` (for future buildpacks), and `.profile.d` (for launch/runtime)
+  #
+  # All values returned must be sourced from Heroku. User provided config vars
+  # are handled in the interfaces that consume this method's result.
+  #
+  # @param environment_name [String] the environment name to use for RACK_ENV/RAILS_ENV
+  # @return [Hash] the ENV var like result
+  def self.default_config_vars(metadata:, ruby_version:, bundler:, environment_name:)
+    @app_secret ||= if metadata.exists?("secret_key_base")
+      metadata.read("secret_key_base").strip
+    else
+      SecureRandom.hex(64).tap { |secret| metadata.write("secret_key_base", secret) }
     end
+
+    LanguagePack::Helpers::DefaultEnvVars.call(
+      is_jruby: ruby_version.jruby?,
+      rack_version: bundler.gem_version("rack"),
+      rails_version: bundler.gem_version("railties"),
+      secret_key_base: @app_secret,
+      environment_name: environment_name
+    )
   end
 
   def default_process_types
-    instrument "ruby.default_process_types" do
-      {
-        "rake"    => "bundle exec rake",
-        "console" => "bundle exec irb"
-      }
+    {
+      "rake" => "bundle exec rake",
+      "console" => "bundle exec irb"
+    }
+  end
+
+  def best_practice_warnings
+    if bundler.has_gem?("asset_sync")
+      warn(<<~WARNING)
+        You are using the `asset_sync` gem.
+        This is not recommended.
+        See https://devcenter.heroku.com/articles/please-do-not-use-asset-sync for more information.
+      WARNING
     end
   end
 
   def compile
-    instrument 'ruby.compile' do
-      # check for new app at the beginning of the compile
-      new_app?
-      Dir.chdir(build_path)
-      remove_vendor_bundle
-      install_ruby
-      install_jvm
-      setup_language_pack_environment
-      setup_profiled
-      allow_git do
-        install_bundler_in_app
-        build_bundler
-        create_database_yml
-        install_binaries
-        run_assets_precompile_rake_task
+    @outdated_version_check = LanguagePack::Helpers::OutdatedRubyVersion.new(
+      current_ruby_version: ruby_version,
+      fetcher: LanguagePack::Installers::HerokuRubyInstaller.fetcher(amd_only_stacks: AMD_ONLY_STACKS, stack: stack, arch: @arch)
+    ).call
+
+    @warn_io.warnings.each { |warning| warnings << warning }
+
+    post_bundler(ruby_version: @ruby_version, app_path: app_path)
+    create_database_yml
+    install_binaries
+    run_assets_precompile_rake_task
+    @report.capture(
+      "gem.railties_version" => bundler.gem_version("railties"),
+      "gem.rack_version" => bundler.gem_version("rack")
+    )
+    if (puma_version = bundler.gem_version("puma"))
+      @report.capture(
+        "gem.puma_version" => puma_version
+      )
+
+      puma_warn_error = LanguagePack::Helpers::PumaWarnError.new(
+        puma_version: puma_version,
+        env: user_env_hash
+      )
+
+      error(puma_warn_error.error) if puma_warn_error.error
+      puma_warn_error.warnings.each do |warning|
+        warn(warning)
       end
-      super
     end
+    config_detect
+    best_practice_warnings
+    warn_outdated_ruby
+    default_config_vars = self.class.default_config_vars(metadata: @metadata, ruby_version: @ruby_version, bundler: bundler, environment_name: environment_name)
+    setup_profiled(ruby_layer_path: "$HOME", gem_layer_path: "$HOME", ruby_version: @ruby_version, default_config_vars: default_config_vars, report: @report) # $HOME is set to /app at run time
+    setup_export(app_path: app_path, ruby_version: @ruby_version, default_config_vars: default_config_vars)
+    cleanup
+    super
+  rescue => e
+    warn_outdated_ruby
+    raise e
   end
 
-private
-
-  # the base PATH environment variable to be used
-  # @return [String] the resulting PATH
-  def default_path
-    # need to remove bin/ folder since it links
-    # to the wrong --prefix ruby binstubs
-    # breaking require. This only applies to Ruby 1.9.2 and 1.8.7.
-    safe_binstubs = binstubs_relative_paths - ["bin"]
-    paths         = [
-      ENV["PATH"],
-      "bin",
-      system_paths,
-    ]
-    paths.unshift("#{slug_vendor_jvm}/bin") if ruby_version.jruby?
-    paths.unshift(safe_binstubs)
+  def cleanup
+  end
 
-    paths.join(":")
+  def config_detect
   end
 
-  def binstubs_relative_paths
-    [
-      "bin",
-      bundler_binstubs_path,
-      "#{slug_vendor_base}/bin"
-    ]
+  # Runs `bundle list` and optionally streams the result to the user
+  #
+  # Streaming helps with build log visibility i.e. "what version of X" am I using at a glance.
+  #
+  # Checks if the information from `bundle list` matches information collected from bundler internals
+  # if not, emits the difference. The goal is to eventually replace requiring bundler internals with
+  # information retrieved from `bundle list`.
+  def self.bundle_list(stream_to_user:, io:, report: HerokuBuildReport::GLOBAL)
+    LanguagePack::Helpers::BundleList::HumanCommand.new(
+      io: io,
+      stream_to_user: stream_to_user
+    ).call
   end
 
-  def system_paths
-    "/usr/local/bin:/usr/bin:/bin"
+  private
+
+  # A bad shebang line looks like this:
+  #
+  # ```
+  # #!/usr/bin/env ruby2.5
+  # ```
+  #
+  # Since `ruby2.5` is not a valid binary name
+  #
+  def self.warn_bad_binstubs(app_path:, warn_object:)
+    check = LanguagePack::Helpers::BinstubCheck.new(
+      warn_object: warn_object,
+      app_root_dir: app_path
+    )
+    check.call
   end
 
-  # the relative path to the bundler directory of gems
-  # @return [String] resulting path
-  def slug_vendor_base
-    instrument 'ruby.slug_vendor_base' do
-      if @slug_vendor_base
-        @slug_vendor_base
-      elsif ruby_version.ruby_version == "1.8.7"
-        @slug_vendor_base = "vendor/bundle/1.8"
-      else
-        @slug_vendor_base = run_no_pipe(%q(ruby -e "require 'rbconfig';puts \"vendor/bundle/#{RUBY_ENGINE}/#{RbConfig::CONFIG['ruby_version']}\"")).chomp
-        error "Problem detecting bundler vendor directory: #{@slug_vendor_base}" unless $?.success?
-        @slug_vendor_base
-      end
-    end
+  def self.warn_bundle_binstub(app_path:, warn_object:)
+    check = LanguagePack::Helpers::BundleBinstubCheck.new(
+      warn_object: warn_object,
+      app_root_dir: app_path
+    )
+    check.call
   end
 
-  # the relative path to the vendored ruby directory
-  # @return [String] resulting path
-  def slug_vendor_ruby
-    "vendor/#{ruby_version.version_without_patchlevel}"
+  def default_malloc_arena_max?
+    return true if @metadata.exists?("default_malloc_arena_max")
+    return @metadata.write("default_malloc_arena_max", "true") if new_app?
+
+    false
   end
 
-  # the relative path to the vendored jvm
-  # @return [String] resulting path
-  def slug_vendor_jvm
-    "vendor/jvm"
+  def self.warn_bundler_upgrade(metadata:, bundler_version:)
+    old_bundler_version = metadata.read("bundler_version").strip if metadata.exists?("bundler_version")
+
+    if old_bundler_version && old_bundler_version != bundler_version
+      warn(<<~WARNING, inline: true)
+        Your bundler version changed from `#{old_bundler_version}` to `#{bundler_version}`.
+
+        If you see problems related to the new bundler version, you can revert to the previous version
+        by updating the `BUNDLED WITH` value in your `Gemfile.lock`. For example:
+
+        ```
+        BUNDLED WITH
+           #{old_bundler_version}
+        ```
+
+        Commit the results to git before redeploying:
+
+        ```
+        $ git add Gemfile.lock
+        $ git commit -m "Revert to previous bundler version"
+        ```
+      WARNING
+    end
   end
 
-  # the absolute path of the build ruby to use during the buildpack
-  # @return [String] resulting path
-  def build_ruby_path
-    "/tmp/#{ruby_version.version_without_patchlevel}"
+  def self.install_ruby_path(app_path:, ruby_version:)
+    app_path.join("vendor").join(ruby_version.version_for_download)
   end
 
   # fetch the ruby version from bundler
   # @return [String, nil] returns the ruby version if detected or nil if none is detected
   def ruby_version
-    instrument 'ruby.ruby_version' do
-      return @ruby_version if @ruby_version
-      new_app           = !File.exist?("vendor/heroku")
-      last_version_file = "buildpack_ruby_version"
-      last_version      = nil
-      last_version      = @metadata.read(last_version_file).chomp if @metadata.exists?(last_version_file)
+    @ruby_version or raise "Internal error: @ruby_version is not set. Call `get_ruby_version` and set @ruby_version"
+  end
 
-      @ruby_version = LanguagePack::RubyVersion.new(bundler,
-        is_new:       new_app,
-        last_version: last_version)
-      return @ruby_version
+  def self.get_ruby_version(metadata:, gemfile_lock:, dot_ruby_version_result: nil, report: HerokuBuildReport::GLOBAL)
+    lockfile_ruby_version = LanguagePack::RubyVersion.from_gemfile_lock(
+      ruby: gemfile_lock.ruby,
+      last_version: metadata.try_read("buildpack_ruby_version")
+    )
+    report.capture(
+      "gemfile_lock.ruby_version.version" => lockfile_ruby_version.ruby_version,
+      "gemfile_lock.ruby_version.engine" => lockfile_ruby_version.engine,
+      "gemfile_lock.ruby_version.engine.version" => lockfile_ruby_version.engine_version,
+      "gemfile_lock.ruby_version.major" => lockfile_ruby_version.major,
+      "gemfile_lock.ruby_version.minor" => lockfile_ruby_version.minor,
+      "gemfile_lock.ruby_version.patch" => lockfile_ruby_version.patch,
+      "gemfile_lock.ruby_version.default" => lockfile_ruby_version.default?
+    )
+
+    if dot_ruby_version_result&.ruby_version
+      report.capture("dot_ruby_version.version" => dot_ruby_version_result.ruby_version.ruby_version)
+
+      if !lockfile_ruby_version.default?
+        report.capture(
+          "dot_ruby_version.vs_gemfile_lock" =>
+            case Gem::Version.new(dot_ruby_version_result.ruby_version.ruby_version) <=> Gem::Version.new(lockfile_ruby_version.ruby_version)
+            when 0 then "match"
+            when 1 then "dot_ruby_version_higher"
+            when -1 then "gemfile_lock_higher"
+            end
+        )
+      end
     end
+
+    lockfile_ruby_version
   end
 
-  # default JAVA_OPTS
-  # return [String] string of JAVA_OPTS
-  def default_java_opts
-    "-Xmx384m -Xss512k -XX:+UseCompressedOops -Dfile.encoding=UTF-8"
+  def set_default_web_concurrency
+    warn(<<~WARNING)
+      Your application is using an undocumented feature SENSIBLE_DEFAULTS
+
+      This feature is not supported and may be removed at any time. Please remove the SENSIBLE_DEFAULTS environment variable from your app.
+
+      $ heroku config:unset SENSIBLE_DEFAULTS
+
+      To configure your application's web concurrency, use the WEB_CONCURRENCY environment variable following this documentation:
+
+      - https://devcenter.heroku.com/articles/deploying-rails-applications-with-the-puma-web-server#recommended-default-puma-process-and-thread-configuration
+      - https://devcenter.heroku.com/articles/h12-request-timeout-in-ruby-mri#puma-pool-usage
+      - https://help.heroku.com/88G3XLA6/what-is-an-acceptable-amount-of-dyno-load
+    WARNING
+
+    <<~EOF
+      case $(ulimit -u) in
+      256)
+        export HEROKU_RAM_LIMIT_MB=${HEROKU_RAM_LIMIT_MB:-512}
+        export WEB_CONCURRENCY=${WEB_CONCURRENCY:-2}
+        export WEB_CONCURRENCY_SET_BY=heroku/ruby
+        ;;
+      512)
+        export HEROKU_RAM_LIMIT_MB=${HEROKU_RAM_LIMIT_MB:-1024}
+        export WEB_CONCURRENCY=${WEB_CONCURRENCY:-4}
+        export WEB_CONCURRENCY_SET_BY=heroku/ruby
+        ;;
+      16384)
+        export HEROKU_RAM_LIMIT_MB=${HEROKU_RAM_LIMIT_MB:-2560}
+        export WEB_CONCURRENCY=${WEB_CONCURRENCY:-8}
+        export WEB_CONCURRENCY_SET_BY=heroku/ruby
+        ;;
+      32768)
+        export HEROKU_RAM_LIMIT_MB=${HEROKU_RAM_LIMIT_MB:-6144}
+        export WEB_CONCURRENCY=${WEB_CONCURRENCY:-16}
+        export WEB_CONCURRENCY_SET_BY=heroku/ruby
+        ;;
+      *)
+        ;;
+      esac
+    EOF
   end
 
   # default JRUBY_OPTS
@@ -193,469 +291,450 @@ def default_jruby_opts
     "-Xcompile.invokedynamic=false"
   end
 
-  # default JAVA_TOOL_OPTIONS
-  # return [String] string of JAVA_TOOL_OPTIONS
-  def default_java_tool_options
-    "-Djava.rmi.server.useCodebaseOnly=true"
-  end
+  # sets up the environment variables for the build process
+  def self.setup_language_pack_environment(app_path:, ruby_version:, bundle_default_without:, default_config_vars:, user_env_hash:)
+    # By default Node can address 1.5GB of memory, a limitation it inherits from
+    # the underlying v8 engine. This can occasionally cause issues during frontend
+    # builds where memory use can exceed this threshold.
+    #
+    # This passes an argument to all Node processes during the build, so that they
+    # can take advantage of all available memory on the build dynos.
+    ENV["NODE_OPTIONS"] ||= "--max_old_space_size=2560"
+
+    default_config_vars.each do |key, value|
+      ENV[key] ||= value
+    end
 
-  # list the available valid ruby versions
-  # @note the value is memoized
-  # @return [Array] list of Strings of the ruby versions available
-  def ruby_versions
-    return @ruby_versions if @ruby_versions
+    paths = []
+    ENV["GEM_PATH"] = app_path.join(ruby_version.bundler_directory).to_s
+    ENV["GEM_HOME"] = ENV["GEM_PATH"]
 
-    Dir.mktmpdir("ruby_versions-") do |tmpdir|
-      Dir.chdir(tmpdir) do
-        @fetchers[:buildpack].fetch("ruby_versions.yml")
-        @ruby_versions = YAML::load_file("ruby_versions.yml")
-      end
-    end
+    ENV["DISABLE_SPRING"] = "1"
 
-    @ruby_versions
-  end
+    # Rails has a binstub for yarn that doesn't work for all applications
+    # we need to ensure that yarn comes before local bin dir for that case
+    paths << yarn_preinstall_bin_path if yarn_preinstalled?
+    paths << app_path.join("bin").to_s
+    paths << app_path.join("vendor/bundle/bin").to_s # Binstubs from bundler, eg. vendor/bundle/bin
+    paths << app_path.join(ruby_version.bundler_directory).join("bin").to_s  # Binstubs from rubygems, eg. vendor/bundle/ruby/2.6.0/bin
+    paths << ENV["PATH"]
 
-  # sets up the environment variables for the build process
-  def setup_language_pack_environment
-    instrument 'ruby.setup_language_pack_environment' do
-      setup_ruby_install_env
-
-      # TODO when buildpack-env-args rolls out, we can get rid of
-      # ||= and the manual setting below
-      config_vars = default_config_vars.each do |key, value|
-        ENV[key] ||= value
-      end
+    ENV["PATH"] = paths.join(":")
 
-      ENV["GEM_PATH"] = slug_vendor_base
-      ENV["GEM_HOME"] = slug_vendor_base
-      ENV["PATH"]     = default_path
+    ENV["BUNDLE_WITHOUT"] ||= user_env_hash["BUNDLE_WITHOUT"] || bundle_default_without
+    if ENV["BUNDLE_WITHOUT"].include?(" ")
+      ENV["BUNDLE_WITHOUT"] = ENV["BUNDLE_WITHOUT"].tr(" ", ":")
+
+      warn("Your BUNDLE_WITHOUT contains a space, we are converting it to a colon `:` BUNDLE_WITHOUT=#{ENV["BUNDLE_WITHOUT"]}", inline: true)
     end
+    ENV["BUNDLE_PATH"] = "vendor/bundle"
+    ENV["BUNDLE_BIN"] = "vendor/bundle/bin"
+    ENV["BUNDLE_DEPLOYMENT"] = "1"
   end
 
-  # sets up the profile.d script for this buildpack
-  def setup_profiled
-    instrument 'setup_profiled' do
-      set_env_override "GEM_PATH", "$HOME/#{slug_vendor_base}:$GEM_PATH"
-      set_env_default  "LANG",     "en_US.UTF-8"
-      set_env_override "PATH",     binstubs_relative_paths.map {|path| "$HOME/#{path}" }.join(":") + ":$PATH"
-
-      if ruby_version.jruby?
-        set_env_default "JAVA_OPTS", default_java_opts
-        set_env_default "JRUBY_OPTS", default_jruby_opts
-        set_env_default "JAVA_TOOL_OPTIONS", default_java_tool_options
-      end
+  # Sets up the environment variables for subsequent processes run by
+  # muiltibuildpack. We can't use profile.d because $HOME isn't set up
+  def setup_export(app_path:, ruby_version:, default_config_vars:)
+    paths = ENV["PATH"].split(":").map do |path|
+      (/^\/.*/ !~ path) ? "#{app_path}/#{path}" : path
+    end.join(":")
+
+    # TODO ensure path exported is correct
+    set_export_path "PATH", paths
+
+    gem_path = app_path.join(ruby_version.bundler_directory)
+    set_export_path "GEM_PATH", gem_path
+    set_export_default "LANG", "en_US.UTF-8"
+
+    # TODO handle jruby
+    if ruby_version.jruby?
+      set_export_default "JRUBY_OPTS", default_jruby_opts
+    end
+
+    set_export_default "BUNDLE_PATH", ENV["BUNDLE_PATH"]
+    set_export_default "BUNDLE_WITHOUT", ENV["BUNDLE_WITHOUT"]
+    set_export_default "BUNDLE_BIN", ENV["BUNDLE_BIN"]
+    set_export_default "BUNDLE_DEPLOYMENT", ENV["BUNDLE_DEPLOYMENT"] # Unset on windows since we delete the Gemfile.lock
+    default_config_vars.each do |key, value|
+      set_export_default key, value
     end
   end
 
-  # install the vendored ruby
-  # @return [Boolean] true if it installs the vendored ruby and false otherwise
-  def install_ruby
-    instrument 'ruby.install_ruby' do
-      return false unless ruby_version
-
-      invalid_ruby_version_message = <<ERROR
-Invalid RUBY_VERSION specified: #{ruby_version.version}
-Valid versions: #{ruby_versions.join(", ")}
-ERROR
-
-      if ruby_version.build?
-        FileUtils.mkdir_p(build_ruby_path)
-        Dir.chdir(build_ruby_path) do
-          ruby_vm = "ruby"
-          instrument "ruby.fetch_build_ruby" do
-            @fetchers[:buildpack].fetch_untar("#{ruby_version.version.sub(ruby_vm, "#{ruby_vm}-build")}.tgz")
-          end
-        end
-        error invalid_ruby_version_message unless $?.success?
-      end
+  # sets up the profile.d script for this buildpack
+  def setup_profiled(ruby_layer_path:, gem_layer_path:, ruby_version:, default_config_vars:, report:)
+    profiled_path = []
 
-      FileUtils.mkdir_p(slug_vendor_ruby)
-      Dir.chdir(slug_vendor_ruby) do
-        instrument "ruby.fetch_ruby" do
-          if ruby_version.rbx?
-            file     = "#{ruby_version.version}.tar.bz2"
-            sha_file = "#{file}.sha1"
-            @fetchers[:rbx].fetch(file)
-            @fetchers[:rbx].fetch(sha_file)
-
-            expected_checksum = File.read(sha_file).chomp
-            actual_checksum   = Digest::SHA1.file(file).hexdigest
-
-            error <<-ERROR_MSG unless expected_checksum == actual_checksum
-RBX Checksum for #{file} does not match.
-Expected #{expected_checksum} but got #{actual_checksum}.
-Please try pushing again in a few minutes.
-ERROR_MSG
-
-            run("tar jxf #{file}")
-            FileUtils.mv(Dir.glob("app/#{slug_vendor_ruby}/*"), ".")
-            FileUtils.rm_rf("app")
-            FileUtils.rm(file)
-            FileUtils.rm(sha_file)
-          else
-            @fetchers[:buildpack].fetch_untar("#{ruby_version.version}.tgz")
-          end
-        end
-      end
-      error invalid_ruby_version_message unless $?.success?
+    default_config_vars.each do |key, value|
+      set_env_default key, value
+    end
 
-      app_bin_dir = "bin"
-      FileUtils.mkdir_p app_bin_dir
+    # Rails has a binstub for yarn that doesn't work for all applications
+    # we need to ensure that yarn comes before local bin dir for that case
+    if yarn_preinstalled?
+      profiled_path << yarn_preinstall_bin_path.gsub(File.expand_path("."), "$HOME")
+    elsif has_yarn_binary?
+      profiled_path << "#{ruby_layer_path}/vendor/#{@yarn_installer.binary_path}"
+    end
+    profiled_path << "$HOME/bin" # /app in production
+    profiled_path << Pathname(gem_layer_path).join("vendor/bundle/bin") # Binstubs from bundler, eg. vendor/bundle/bin
+    profiled_path << Pathname(gem_layer_path).join(ruby_version.bundler_directory, "bin") # Binstubs from rubygems, eg. vendor/bundle/ruby/2.6.0/bin
+    profiled_path << "$PATH"
 
-      run("ln -s ruby #{slug_vendor_ruby}/bin/ruby.exe")
+    set_env_override "GEM_PATH", [Pathname(gem_layer_path).join(ruby_version.bundler_directory), "$GEM_PATH"].join(":")
+    set_env_override "PATH", profiled_path.join(":")
+    set_env_override "DISABLE_SPRING", "1"
 
-      Dir["#{slug_vendor_ruby}/bin/*"].each do |vendor_bin|
-        run("ln -s ../#{vendor_bin} #{app_bin_dir}")
-      end
+    set_env_default "MALLOC_ARENA_MAX", "2" if default_malloc_arena_max?
 
-      @metadata.write("buildpack_ruby_version", ruby_version.version)
+    web_concurrency = env("SENSIBLE_DEFAULTS") ? set_default_web_concurrency : ""
+    report.capture("web_concurrency.sensible_defaults" => web_concurrency.empty?)
+    add_to_profiled(web_concurrency, filename: "WEB_CONCURRENCY.sh", mode: "w") # always write that file, even if its empty (meaning no defaults apply), for interop with other buildpacks - and we overwrite the file rather than appending (which is the default)
 
-      topic "Using Ruby version: #{ruby_version.version}"
-      if !ruby_version.set
-        warn(<<WARNING)
-You have not declared a Ruby version in your Gemfile.
-To set your Ruby version add this line to your Gemfile:
-#{ruby_version.to_gemfile}
-# See https://devcenter.heroku.com/articles/ruby-versions for more information.
-WARNING
-      end
+    # TODO handle JRUBY
+    if ruby_version.jruby?
+      set_env_default "JRUBY_OPTS", default_jruby_opts
     end
 
-    true
+    set_env_default "BUNDLE_PATH", ENV["BUNDLE_PATH"]
+    set_env_default "BUNDLE_WITHOUT", ENV["BUNDLE_WITHOUT"]
+    set_env_default "BUNDLE_BIN", ENV["BUNDLE_BIN"]
+    set_env_default "BUNDLE_DEPLOYMENT", ENV["BUNDLE_DEPLOYMENT"] if ENV["BUNDLE_DEPLOYMENT"] # Unset on windows since we delete the Gemfile.lock
   end
 
-  def new_app?
-    @new_app ||= !File.exist?("vendor/heroku")
+  def warn_outdated_ruby
+    return unless defined?(@outdated_version_check)
+
+    @warn_outdated ||= begin
+      @outdated_version_check.join
+
+      warn_outdated_minor
+      warn_outdated_eol
+      warn_stack_upgrade
+      true
+    end
   end
 
-  # vendors JVM into the slug for JRuby
-  def install_jvm
-    instrument 'ruby.install_jvm' do
-      if ruby_version.jruby?
-        jvm_version =
-          if Gem::Version.new(ruby_version.engine_version) >= Gem::Version.new("1.7.4")
-            LATEST_JVM_VERSION
-          else
-            LEGACY_JVM_VERSION
-          end
+  def warn_stack_upgrade
+    return unless defined?(@ruby_download_check)
+    return unless @ruby_download_check.next_stack(current_stack: stack)
+    return if @ruby_download_check.exists_on_next_stack?(current_stack: stack)
 
-        topic "Installing JVM: #{jvm_version}"
+    warn(<<~WARNING)
+      Your Ruby version is not present on the next stack
 
-        FileUtils.mkdir_p(slug_vendor_jvm)
-        Dir.chdir(slug_vendor_jvm) do
-          @fetchers[:jvm].fetch_untar("#{jvm_version}.tar.gz")
-        end
+      You are currently using #{ruby_version.version_for_download} on #{stack} stack.
+      This version does not exist on #{@ruby_download_check.next_stack(current_stack: stack)}. In order to upgrade your stack you will
+      need to upgrade to a supported Ruby version.
 
-        bin_dir = "bin"
-        FileUtils.mkdir_p bin_dir
-        Dir["#{slug_vendor_jvm}/bin/*"].each do |bin|
-          run("ln -s ../#{bin} #{bin_dir}")
-        end
-      end
-    end
-  end
+      For a list of supported Ruby versions see:
+        https://devcenter.heroku.com/articles/ruby-support#supported-runtimes
 
-  # find the ruby install path for its binstubs during build
-  # @return [String] resulting path or empty string if ruby is not vendored
-  def ruby_install_binstub_path
-    @ruby_install_binstub_path ||=
-      if ruby_version.build?
-        "#{build_ruby_path}/bin"
-      elsif ruby_version
-        "#{slug_vendor_ruby}/bin"
-      else
-        ""
-      end
+      For a list of the oldest Ruby versions present on a given stack see:
+        https://devcenter.heroku.com/articles/ruby-support#oldest-available-runtimes
+    WARNING
   end
 
-  # setup the environment so we can use the vendored ruby
-  def setup_ruby_install_env
-    instrument 'ruby.setup_ruby_install_env' do
-      ENV["PATH"] = "#{ruby_install_binstub_path}:#{ENV["PATH"]}"
+  def warn_outdated_eol
+    return unless @outdated_version_check.maybe_eol?
 
-      if ruby_version.jruby?
-        ENV['JAVA_OPTS']  = default_java_opts
-      end
+    if @outdated_version_check.eol?
+      warn(<<~WARNING)
+        EOL Ruby Version
+
+        You are using a Ruby version that has reached its End of Life (EOL)
+
+        We strongly suggest you upgrade to Ruby #{@outdated_version_check.suggest_ruby_eol_version} or later
+
+        Your current Ruby version no longer receives security updates from
+        Ruby Core and may have serious vulnerabilities. While you will continue
+        to be able to deploy on Heroku with this Ruby version you must upgrade
+        to a non-EOL version to be eligible to receive support.
+
+        Upgrade your Ruby version as soon as possible.
+
+        For a list of supported Ruby versions see:
+          https://devcenter.heroku.com/articles/ruby-support#supported-runtimes
+      WARNING
+    else
+      # Maybe EOL
+      warn(<<~WARNING)
+        Potential EOL Ruby Version
+
+        You are using a Ruby version that has either reached its End of Life (EOL)
+        or will reach its End of Life on December 25th of this year.
+
+        We suggest you upgrade to Ruby #{@outdated_version_check.suggest_ruby_eol_version} or later
+
+        Once a Ruby version becomes EOL, it will no longer receive
+        security updates from Ruby core and may have serious vulnerabilities.
+
+        Please upgrade your Ruby version.
+
+        For a list of supported Ruby versions see:
+          https://devcenter.heroku.com/articles/ruby-support#supported-runtimes
+      WARNING
     end
   end
 
-  # installs vendored gems into the slug
-  def install_bundler_in_app
-    instrument 'ruby.install_language_pack_gems' do
-      FileUtils.mkdir_p(slug_vendor_base)
-      Dir.chdir(slug_vendor_base) do |dir|
-        `cp -R #{bundler.bundler_path}/. .`
+  def warn_outdated_minor
+    return if @outdated_version_check.latest_minor_version?
+
+    warn(<<~WARNING)
+      There is a more recent Ruby version available for you to use:
+
+      #{@outdated_version_check.suggested_ruby_minor_version}
+
+      The latest version will include security and bug fixes. We always recommend
+      running the latest version of your minor release.
+
+      Please upgrade your Ruby version.
+
+      For all available Ruby versions see:
+        https://devcenter.heroku.com/articles/ruby-support#supported-runtimes
+    WARNING
+  end
+
+  # install the vendored ruby
+  # @return [Boolean] true if it installs the vendored ruby and false otherwise
+  def self.install_ruby(app_path:, ruby_version:, stack:, arch:, metadata:, io:)
+    # Could do a compare operation to avoid re-downloading ruby
+    return false unless ruby_version
+
+    installer = LanguagePack::Installers::HerokuRubyInstaller.new(
+      amd_only_stacks: AMD_ONLY_STACKS,
+      stack: stack,
+      arch: arch,
+      app_path: app_path,
+      env: ENV
+    )
+
+    @ruby_download_check = LanguagePack::Helpers::DownloadPresence.new(
+      amd_only_stacks: AMD_ONLY_STACKS,
+      file_name: ruby_version.file_name,
+      arch: arch
+    )
+    @ruby_download_check.call
+
+    installer.install(ruby_version, install_ruby_path(app_path: app_path, ruby_version: ruby_version))
+
+    metadata.write("buildpack_ruby_version", ruby_version.version_for_download)
+
+    io.topic "Using Ruby version: #{ruby_version.version_for_download}"
+    if ruby_version.default?
+      warn(<<~WARNING)
+        You have not declared a Ruby version in your Gemfile.
+
+        To declare a Ruby version add this line to your Gemfile:
+
+        ```
+        ruby "#{LanguagePack::RubyVersion::DEFAULT_VERSION_NUMBER}"
+        ```
+
+        For more information see:
+          https://devcenter.heroku.com/articles/ruby-versions
+      WARNING
+    end
+
+    true
+  rescue LanguagePack::Fetcher::FetchError
+    if @ruby_download_check.does_not_exist?
+      message = <<~ERROR
+        The Ruby version you are trying to install does not exist: #{ruby_version.version_for_download}
+      ERROR
+    else
+      message = <<~ERROR
+        The Ruby version you are trying to install does not exist on this stack.
+
+        You are trying to install #{ruby_version.version_for_download} on #{stack}.
+
+        Ruby #{ruby_version.version_for_download} is present on the following stacks:
+
+          - #{@ruby_download_check.valid_stack_list.join("\n  - ")}
+      ERROR
+
+      if env("CI")
+        message << <<~ERROR
+
+          On Heroku CI you can set your stack in the `app.json`. For example:
+
+          ```
+          "stack": "heroku-24"
+          ```
+        ERROR
       end
     end
+
+    message << <<~ERROR
+
+      Heroku recommends you use the latest supported Ruby version listed here:
+        https://devcenter.heroku.com/articles/ruby-support#supported-runtimes
+
+      For more information on syntax for declaring a Ruby version see:
+        https://devcenter.heroku.com/articles/ruby-versions
+    ERROR
+
+    io.error message
   end
 
   # default set of binaries to install
   # @return [Array] resulting list
   def binaries
-    add_node_js_binary
+    add_node_js_binary + add_yarn_binary
   end
 
   # vendors binaries into the slug
   def install_binaries
-    instrument 'ruby.install_binaries' do
-      binaries.each {|binary| install_binary(binary) }
-      Dir["bin/*"].each {|path| run("chmod +x #{path}") }
-    end
+    binaries.each { |binary| install_binary(binary) }
+    Dir["bin/*"].each { |path| run("chmod +x #{path}") }
   end
 
   # vendors individual binary into the slug
   # @param [String] name of the binary package from S3.
-  #   Example: https://s3.amazonaws.com/language-pack-ruby/node-0.4.7.tgz, where name is "node-0.4.7"
+  #   Example: https://heroku-buildpack-ruby.s3.dualstack.us-east-1.amazonaws.com/node-0.4.7.tgz, where name is "node-0.4.7"
   def install_binary(name)
+    topic "Installing #{name}"
     bin_dir = "bin"
     FileUtils.mkdir_p bin_dir
     Dir.chdir(bin_dir) do |dir|
-      @fetchers[:buildpack].fetch_untar("#{name}.tgz")
+      if /^node-/.match?(name)
+        @node_installer.install
+        # need to set PATH here b/c `node-gyp` can change the CWD, but still depends on executing node.
+        # the current PATH is relative, but it needs to be absolute for this.
+        # doing this here also prevents it from being exported during runtime
+        node_bin_path = File.absolute_path(".")
+        # this needs to be set after so other binaries in bin/ don't take precedence"
+        ENV["PATH"] = "#{ENV["PATH"]}:#{node_bin_path}"
+      elsif /^yarn-/.match?(name)
+        FileUtils.mkdir_p("../vendor")
+        Dir.chdir("../vendor") do |vendor_dir|
+          @yarn_installer.install
+          yarn_path = File.absolute_path("#{vendor_dir}/#{@yarn_installer.binary_path}")
+          ENV["PATH"] = "#{yarn_path}:#{ENV["PATH"]}"
+        end
+      else
+        @fetchers[:buildpack].fetch_untar("#{name}.tgz")
+      end
     end
   end
 
   # removes a binary from the slug
   # @param [String] relative path of the binary on the slug
   def uninstall_binary(path)
-    FileUtils.rm File.join('bin', File.basename(path)), :force => true
-  end
-
-  def load_default_cache?
-    new_app? && ruby_version.default?
-  end
-
-  # loads a default bundler cache for new apps to speed up initial bundle installs
-  def load_default_cache
-    instrument "ruby.load_default_cache" do
-      if load_default_cache?
-        puts "New app detected loading default bundler cache"
-        patchlevel = run("ruby -e 'puts RUBY_PATCHLEVEL'").chomp
-        cache_name  = "#{DEFAULT_RUBY_VERSION}-p#{patchlevel}-default-cache"
-        @fetchers[:buildpack].fetch_untar("#{cache_name}.tgz")
-      end
-    end
-  end
-
-  # install libyaml into the LP to be referenced for psych compilation
-  # @param [String] tmpdir to store the libyaml files
-  def install_libyaml(dir)
-    instrument 'ruby.install_libyaml' do
-      FileUtils.mkdir_p dir
-      Dir.chdir(dir) do |dir|
-        @fetchers[:buildpack].fetch_untar("#{LIBYAML_PATH}.tgz")
-      end
-    end
+    FileUtils.rm File.join("bin", File.basename(path)), force: true
   end
 
   # remove `vendor/bundle` that comes from the git repo
   # in case there are native ext.
   # users should be using `bundle pack` instead.
   # https://github.com/heroku/heroku-buildpack-ruby/issues/21
-  def remove_vendor_bundle
-    if File.exists?("vendor/bundle")
-      warn(<<WARNING)
-Removing `vendor/bundle`.
-Checking in `vendor/bundle` is not supported. Please remove this directory
-and add it to your .gitignore. To vendor your gems with Bundler, use
-`bundle pack` instead.
-WARNING
-      FileUtils.rm_rf("vendor/bundle")
+  def self.remove_vendor_bundle(app_path:)
+    vendor_bundle = app_path.join("vendor").join("bundle")
+    if vendor_bundle.exist?
+      warn(<<~WARNING)
+        Removing `vendor/bundle`.
+        Checking in `vendor/bundle` is not supported. Please remove this directory
+        and add it to your .gitignore. To vendor your gems with Bundler, use
+        `bundle pack` instead.
+      WARNING
+      vendor_bundle.rmtree
     end
   end
 
-  def bundler_binstubs_path
-    "vendor/bundle/bin"
-  end
-
   # runs bundler to install the dependencies
-  def build_bundler
-    instrument 'ruby.build_bundler' do
-      log("bundle") do
-        bundle_without = env("BUNDLE_WITHOUT") || "development:test"
-        bundle_bin     = "bundle"
-        bundle_command = "#{bundle_bin} install --without #{bundle_without} --path vendor/bundle --binstubs #{bundler_binstubs_path}"
-        bundle_command << " -j4"
-
-        if bundler.windows_gemfile_lock?
-          warn(<<WARNING, inline: true)
-Removing `Gemfile.lock` because it was generated on Windows.
-Bundler will do a full resolve so native gems are handled properly.
-This may result in unexpected gem versions being used in your app.
-In rare occasions Bundler may not be able to resolve your dependencies at all.
-https://devcenter.heroku.com/articles/bundler-windows-gemfile
-WARNING
-
-          log("bundle", "has_windows_gemfile_lock")
-          File.unlink("Gemfile.lock")
-        else
-          # using --deployment is preferred if we can
-          bundle_command += " --deployment"
-          cache.load ".bundle"
-        end
+  def self.build_bundler(app_path:, io:, bundler_cache:, bundler_version:, bundler_output:, ruby_version:)
+    if app_path.join(".bundle/config").exist?
+      warn(<<~WARNING, inline: true)
+        You have the `.bundle/config` file checked into your repository
+          It contains local state like the location of the installed bundle
+          as well as configured git local gems, and other settings that should
+        not be shared between multiple checkouts of a single repo. Please
+        remove the `.bundle/` folder from your repo and add it to your `.gitignore` file.
+
+        https://devcenter.heroku.com/articles/bundler-configuration
+      WARNING
+    end
 
-        topic("Installing dependencies using #{bundler.version}")
-        load_bundler_cache
-
-        bundler_output = ""
-        bundle_time    = nil
-        Dir.mktmpdir("libyaml-") do |tmpdir|
-          libyaml_dir = "#{tmpdir}/#{LIBYAML_PATH}"
-          install_libyaml(libyaml_dir)
-
-          # need to setup compile environment for the psych gem
-          yaml_include   = File.expand_path("#{libyaml_dir}/include").shellescape
-          yaml_lib       = File.expand_path("#{libyaml_dir}/lib").shellescape
-          pwd            = Dir.pwd
-          bundler_path   = "#{pwd}/#{slug_vendor_base}/gems/#{BUNDLER_GEM_PATH}/lib"
-          # we need to set BUNDLE_CONFIG and BUNDLE_GEMFILE for
-          # codon since it uses bundler.
-          env_vars       = {
-            "BUNDLE_GEMFILE"                => "#{pwd}/Gemfile",
-            "BUNDLE_CONFIG"                 => "#{pwd}/.bundle/config",
-            "CPATH"                         => noshellescape("#{yaml_include}:$CPATH"),
-            "CPPATH"                        => noshellescape("#{yaml_include}:$CPPATH"),
-            "LIBRARY_PATH"                  => noshellescape("#{yaml_lib}:$LIBRARY_PATH"),
-            "RUBYOPT"                       => syck_hack,
-            "NOKOGIRI_USE_SYSTEM_LIBRARIES" => "true"
-          }
-          env_vars["BUNDLER_LIB_PATH"] = "#{bundler_path}" if ruby_version.ruby_version == "1.8.7"
-          puts "Running: #{bundle_command}"
-          instrument "ruby.bundle_install" do
-            bundle_time = Benchmark.realtime do
-              bundler_output << pipe("#{bundle_command} --no-clean", out: "2>&1", env: env_vars, user_env: true)
-            end
-          end
-        end
+    bundle_command = +""
+    bundle_command << "BUNDLE_WITHOUT='#{ENV["BUNDLE_WITHOUT"]}' "
+    bundle_command << "BUNDLE_PATH=#{ENV["BUNDLE_PATH"]} "
+    bundle_command << "BUNDLE_BIN=#{ENV["BUNDLE_BIN"]} "
+    bundle_command << "BUNDLE_DEPLOYMENT=#{ENV["BUNDLE_DEPLOYMENT"]} " if ENV["BUNDLE_DEPLOYMENT"] # Unset on windows since we delete the Gemfile.lock
+    bundle_command << "bundle install -j4"
 
-        if $?.success?
-          puts "Bundle completed (#{"%.2f" % bundle_time}s)"
-          log "bundle", :status => "success"
-          puts "Cleaning up the bundler cache."
-          instrument "ruby.bundle_clean" do
-            # Only show bundle clean output when not using default cache
-            if load_default_cache?
-              run "bundle clean > /dev/null"
-            else
-              pipe("#{bundle_bin} clean", out: "2> /dev/null")
-            end
-          end
-          cache.store ".bundle"
-          cache.store "vendor/bundle"
-
-          # Keep gem cache out of the slug
-          FileUtils.rm_rf("#{slug_vendor_base}/cache")
-        else
-          log "bundle", :status => "failure"
-          error_message = "Failed to install gems via Bundler."
-          puts "Bundler Output: #{bundler_output}"
-          if bundler_output.match(/An error occurred while installing sqlite3/)
-            error_message += <<ERROR
-
-
-Detected sqlite3 gem which is not supported on Heroku.
-https://devcenter.heroku.com/articles/sqlite3
-ERROR
-          end
+    io.topic("Installing dependencies using bundler #{bundler_version}")
+    env_vars = {}
 
-          error error_message
-        end
-      end
-    end
-  end
+    env_vars["BUNDLE_GEMFILE"] = app_path.join("Gemfile").to_s
+    env_vars["BUNDLE_CONFIG"] = app_path.join(".bundle/config").to_s
+    env_vars["NOKOGIRI_USE_SYSTEM_LIBRARIES"] = "true"
+    env_vars["BUNDLE_DISABLE_VERSION_CHECK"] = "true"
 
-  # RUBYOPT line that requires syck_hack file
-  # @return [String] require string if needed or else an empty string
-  def syck_hack
-    instrument "ruby.syck_hack" do
-      syck_hack_file = File.expand_path(File.join(File.dirname(__FILE__), "../../vendor/syck_hack"))
-      rv             = run_stdout('ruby -e "puts RUBY_VERSION"').chomp
-      # < 1.9.3 includes syck, so we need to use the syck hack
-      if Gem::Version.new(rv) < Gem::Version.new("1.9.3")
-        "-r#{syck_hack_file}"
-      else
-        ""
-      end
+    io.puts "Running: #{bundle_command}"
+    bundle_time = Benchmark.realtime do
+      bundler_output << pipe("#{bundle_command} --no-clean", out: "2>&1", env: env_vars, user_env: true)
     end
-  end
-
-  # writes ERB based database.yml for Rails. The database.yml uses the DATABASE_URL from the environment during runtime.
-  def create_database_yml
-    instrument 'ruby.create_database_yml' do
-      log("create_database_yml") do
-        return unless File.directory?("config")
-        topic("Writing config/database.yml to read from DATABASE_URL")
-        File.open("config/database.yml", "w") do |file|
-          file.puts <<-DATABASE_YML
-<%
-
-require 'cgi'
-require 'uri'
-
-begin
-  uri = URI.parse(ENV["DATABASE_URL"])
-rescue URI::InvalidURIError
-  raise "Invalid DATABASE_URL"
-end
 
-raise "No RACK_ENV or RAILS_ENV found" unless ENV["RAILS_ENV"] || ENV["RACK_ENV"]
+    if $?.success?
+      io.puts "Bundle completed (#{"%.2f" % bundle_time}s)"
+      io.puts "Cleaning up the bundler cache."
+      pipe("bundle clean", out: "2> /dev/null", user_env: true, env: env_vars)
+      bundler_cache.store
 
-def attribute(name, value, force_string = false)
-  if value
-    value_string =
-      if force_string
-        '"' + value + '"'
-      else
-        value
+      # Keep gem cache out of the slug
+      app_path.join(ruby_version.bundler_directory).join("cache").rmtree
+    else
+      error_message = "Failed to install gems via Bundler."
+      io.puts "Bundler Output: #{bundler_output}"
+      if /An error occurred while installing sqlite3/.match?(bundler_output)
+        error_message += <<~ERROR
+
+          Detected sqlite3 gem which is not supported on Heroku:
+          https://devcenter.heroku.com/articles/sqlite3
+        ERROR
       end
-    "\#{name}: \#{value_string}"
-  else
-    ""
-  end
-end
 
-adapter = uri.scheme
-adapter = "postgresql" if adapter == "postgres"
+      if /but your Gemfile specified/.match?(bundler_output)
+        error_message += <<~ERROR
 
-database = (uri.path || "").split("/")[1]
+          Detected a mismatch between your Ruby version installed and
+          Ruby version specified in Gemfile or Gemfile.lock. You can
+          correct this by running:
 
-username = uri.user
-password = uri.password
+              $ bundle update --ruby
+              $ git add Gemfile.lock
+              $ git commit -m "update ruby version"
 
-host = uri.host
-port = uri.port
+          If this does not solve the issue please see this documentation:
 
-params = CGI.parse(uri.query || "")
-
-%>
+          https://devcenter.heroku.com/articles/ruby-versions#your-ruby-version-is-x-but-your-gemfile-specified-y
+        ERROR
+      end
 
-<%= ENV["RAILS_ENV"] || ENV["RACK_ENV"] %>:
-  <%= attribute "adapter",  adapter %>
-  <%= attribute "database", database %>
-  <%= attribute "username", username %>
-  <%= attribute "password", password, true %>
-  <%= attribute "host",     host %>
-  <%= attribute "port",     port %>
+      io.error error_message
+    end
+  end
 
-<% params.each do |key, value| %>
-  <%= key %>: <%= value.first %>
-<% end %>
-        DATABASE_YML
-        end
-      end
+  def post_bundler(ruby_version:, app_path:)
+    Dir[app_path.join(ruby_version.bundler_directory, "**", ".git")].each do |dir|
+      FileUtils.rm_rf(dir)
     end
+    bundler.clean
   end
 
   def rake
     @rake ||= begin
-      LanguagePack::Helpers::RakeRunner.new(
-                bundler.has_gem?("rake") || ruby_version.rake_is_vendored?
-              ).load_rake_tasks!(env: rake_env)
+      raise_on_fail = bundler.gem_version("railties") && bundler.gem_version("railties") > Gem::Version.new("3.x")
+
+      topic "Detecting rake tasks"
+      rake = LanguagePack::Helpers::RakeRunner.new
+      rake.load_rake_tasks!({env: rake_env}, raise_on_fail)
+      rake
     end
   end
 
   def rake_env
     if database_url
-      { "DATABASE_URL" => database_url }
+      {"DATABASE_URL" => database_url}
     else
       {}
     end.merge(user_env_hash)
@@ -665,125 +744,293 @@ def database_url
     env("DATABASE_URL") if env("DATABASE_URL")
   end
 
-  # executes the block with GIT_DIR environment variable removed since it can mess with the current working directory git thinks it's in
-  # @param [block] block to be executed in the GIT_DIR free context
-  def allow_git(&blk)
-    git_dir = ENV.delete("GIT_DIR") # can mess with bundler
-    blk.call
-    ENV["GIT_DIR"] = git_dir
-  end
-
   # decides if we need to enable the dev database addon
   # @return [Array] the database addon if the pg gem is detected or an empty Array if it isn't.
   def add_dev_database_addon
-    bundler.has_gem?("pg") ? ['heroku-postgresql:hobby-dev'] : []
+    return [] if env("HEROKU_SKIP_DATABASE_PROVISION")
+
+    ([
+      "pg",
+      "activerecord-jdbcpostgresql-adapter",
+      "jdbc-postgres",
+      "jdbc-postgresql",
+      "jruby-pg",
+      "rjack-jdbc-postgres",
+      "tgbyte-activerecord-jdbcpostgresql-adapter"
+    ].any? { |a| bundler.has_gem?(a) }) ? ["heroku-postgresql"] : []
   end
 
   # decides if we need to install the node.js binary
   # @note execjs will blow up if no JS RUNTIME is detected and is loaded.
   # @return [Array] the node.js binary path if we need it or an empty Array
   def add_node_js_binary
-    bundler.has_gem?('execjs') ? [NODE_JS_BINARY_PATH] : []
+    return [] if node_js_preinstalled?
+
+    if Pathname(app_path).join("package.json").exist? ||
+        bundler.has_gem?("execjs") ||
+        bundler.has_gem?("webpacker")
+
+      version = @node_installer.version
+      old_version = @metadata.fetch("default_node_version") { version }
+
+      # Make available for `rake assets:precompile` and other sub-shells
+      ENV["UV_USE_IO_URING"] ||= "0"
+      # Make available to future buildpacks (export), but not runtime (profile.d)
+      set_export_default "UV_USE_IO_URING", "0"
+
+      if old_version != version
+        warn(<<~WARNING, inline: true)
+          Default version of Node.js changed (#{old_version} to #{version})
+        WARNING
+      end
+
+      warn(<<~WARNING, inline: true)
+        Installing a default version (#{version}) of Node.js.
+        This version is not pinned and can change over time, causing unexpected failures.
+
+        Heroku recommends placing the `heroku/nodejs` buildpack in front of
+        `heroku/ruby` to install a specific version of node:
+
+        https://devcenter.heroku.com/articles/ruby-support-reference#node-js-and-yarn-support
+      WARNING
+
+      [@node_installer.binary_path]
+    else
+      []
+    end
   end
 
-  def run_assets_precompile_rake_task
-    instrument 'ruby.run_assets_precompile_rake_task' do
+  def add_yarn_binary
+    return [] if yarn_preinstalled?
 
-      precompile = rake.task("assets:precompile")
-      return true unless precompile.is_defined?
+    if Pathname(app_path).join("yarn.lock").exist? || bundler.has_gem?("webpacker")
 
-      topic "Running: rake assets:precompile"
-      precompile.invoke(env: rake_env)
-      if precompile.success?
-        puts "Asset precompilation completed (#{"%.2f" % precompile.time}s)"
-      else
-        log "assets_precompile", :status => "failure"
-        error "Precompiling assets failed."
+      version = @yarn_installer.version
+      old_version = @metadata.fetch("default_yarn_version") { version }
+
+      # Make available for `rake assets:precompile` and other sub-shells
+      ENV["UV_USE_IO_URING"] ||= "0"
+      # Make available to future buildpacks (export), but not runtime (profile.d)
+      set_export_default "UV_USE_IO_URING", "0"
+
+      if old_version != version
+        warn(<<~WARNING, inline: true)
+          Default version of Yarn changed (#{old_version} to #{version})
+        WARNING
       end
+
+      warn(<<~WARNING, inline: true)
+        Installing a default version (#{version}) of Yarn
+        This version is not pinned and can change over time, causing unexpected failures.
+
+        Heroku recommends placing the `heroku/nodejs` buildpack in front of the `heroku/ruby`
+        buildpack as it offers more comprehensive Node.js support, including the ability to
+        customise the Node.js version:
+
+        https://devcenter.heroku.com/articles/ruby-support-reference#node-js-and-yarn-support
+      WARNING
+
+      [@yarn_installer.name]
+    else
+      []
     end
   end
 
-  def bundler_cache
-    "vendor/bundle"
+  def has_yarn_binary?
+    add_yarn_binary.any?
   end
 
-  def load_bundler_cache
-    instrument "ruby.load_bundler_cache" do
-      cache.load "vendor"
+  # checks if node.js is installed via the official heroku-buildpack-nodejs using multibuildpack
+  # @return String if it's detected and false if it isn't
+  def node_preinstall_bin_path
+    return @node_preinstall_bin_path if defined?(@node_preinstall_bin_path)
+
+    legacy_path = "#{Dir.pwd}/#{NODE_BP_PATH}"
+    path = run("command -v node").strip
+    @node_preinstall_bin_path = if path && $?.success?
+      path
+    elsif run("#{legacy_path}/node -v") && $?.success?
+      legacy_path
+    else
+      false
+    end
+  end
+  alias_method :node_js_preinstalled?, :node_preinstall_bin_path
 
-      full_ruby_version       = run_stdout(%q(ruby -v)).chomp
-      rubygems_version        = run_stdout(%q(gem -v)).chomp
-      heroku_metadata         = "vendor/heroku"
-      old_rubygems_version    = nil
-      ruby_version_cache      = "ruby_version"
-      buildpack_version_cache = "buildpack_version"
-      bundler_version_cache   = "bundler_version"
-      rubygems_version_cache  = "rubygems_version"
+  def node_not_preinstalled?
+    !node_js_preinstalled?
+  end
 
-      old_rubygems_version = @metadata.read(ruby_version_cache).chomp if @metadata.exists?(ruby_version_cache)
+  def yarn_preinstall_bin_path
+    LanguagePack::Ruby.yarn_preinstall_bin_path
+  end
 
-      load_default_cache
+  # Example: tmp/build_8523f77fb96a956101d00988dfeed9d4/.heroku/yarn/bin/ (without the `yarn` at the end)
+  def self.yarn_preinstall_bin_path
+    (yarn_preinstall_binary_path || "").chomp("/yarn")
+  end
 
-      # fix bug from v37 deploy
-      if File.exists?("vendor/ruby_version")
-        puts "Broken cache detected. Purging build cache."
-        cache.clear("vendor")
-        FileUtils.rm_rf("vendor/ruby_version")
-        purge_bundler_cache
-        # fix bug introduced in v38
-      elsif !@metadata.exists?(buildpack_version_cache) && @metadata.exists?(ruby_version_cache)
-        puts "Broken cache detected. Purging build cache."
-        purge_bundler_cache
-      elsif cache.exists?(bundler_cache) && @metadata.exists?(ruby_version_cache) && full_ruby_version != @metadata.read(ruby_version_cache).chomp
-        puts "Ruby version change detected. Clearing bundler cache."
-        puts "Old: #{@metadata.read(ruby_version_cache).chomp}"
-        puts "New: #{full_ruby_version}"
-        purge_bundler_cache
-      end
+  # Example `tmp/build_8523f77fb96a956101d00988dfeed9d4/.heroku/yarn/bin/yarn`
+  def self.yarn_preinstall_binary_path
+    return @yarn_preinstall_binary_path if defined?(@yarn_preinstall_binary_path)
 
-      # fix git gemspec bug from Bundler 1.3.0+ upgrade
-      if File.exists?(bundler_cache) && !@metadata.exists?(bundler_version_cache) && !run("find vendor/bundle/*/*/bundler/gems/*/ -name *.gemspec").include?("No such file or directory")
-        puts "Old bundler cache detected. Clearing bundler cache."
-        purge_bundler_cache
-      end
+    path = run("command -v yarn").strip
+    @yarn_preinstall_binary_path = if path && $?.success?
+      path
+    else
+      false
+    end
+  end
 
-      # fix for https://github.com/heroku/heroku-buildpack-ruby/issues/86
-      if (!@metadata.exists?(rubygems_version_cache) ||
-          (old_rubygems_version == "2.0.0" && old_rubygems_version != rubygems_version)) &&
-          @metadata.exists?(ruby_version_cache) && @metadata.read(ruby_version_cache).chomp.include?("ruby 2.0.0p0")
-        puts "Updating to rubygems #{rubygems_version}. Clearing bundler cache."
-        purge_bundler_cache
-      end
+  def yarn_preinstalled?
+    LanguagePack::Ruby.yarn_preinstalled?
+  end
 
-      # fix for https://github.com/sparklemotion/nokogiri/issues/923
-      if @metadata.exists?(buildpack_version_cache) && (bv = @metadata.read(buildpack_version_cache).sub('v', '').to_i) && bv != 0 && bv <= 76
-        puts "Fixing nokogiri install. Clearing bundler cache."
-        puts "See https://github.com/sparklemotion/nokogiri/issues/923."
-        purge_bundler_cache
-      end
+  def self.yarn_preinstalled?
+    yarn_preinstall_binary_path
+  end
 
-      # recompile nokogiri to use new libyaml
-      if @metadata.exists?(buildpack_version_cache) && (bv = @metadata.read(buildpack_version_cache).sub('v', '').to_i) && bv != 0 && bv <= 99 && bundler.has_gem?("psych")
-        puts "Need to recompile psych for CVE-2013-6393. Clearing bundler cache."
-        puts "See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=737076."
-        purge_bundler_cache
-      end
+  def run_assets_precompile_rake_task
+    precompile = rake.task("assets:precompile")
+    return true unless precompile.is_defined?
+
+    topic "Precompiling assets"
+    precompile.invoke(env: rake_env)
+    if precompile.success?
+      puts "Asset precompilation completed (#{"%.2f" % precompile.time}s)"
+    else
+      precompile_fail(precompile.output)
+    end
+  end
 
-      FileUtils.mkdir_p(heroku_metadata)
-      @metadata.write(ruby_version_cache, full_ruby_version, false)
-      @metadata.write(buildpack_version_cache, BUILDPACK_VERSION, false)
-      @metadata.write(bundler_version_cache, BUNDLER_VERSION, false)
-      @metadata.write(rubygems_version_cache, rubygems_version, false)
-      @metadata.save
+  def precompile_fail(output)
+    msg = "Precompiling assets failed.\n"
+    if /(127\.0\.0\.1)|(org\.postgresql\.util)/.match?(output)
+      msg << "Attempted to access a nonexistent database:\n"
+      msg << "https://devcenter.heroku.com/articles/pre-provision-database\n"
     end
+
+    sprockets_version = bundler.gem_version("sprockets")
+    if output.match(/Sprockets::FileNotFound/) && sprockets_version < Gem::Version.new("4.0.0.beta7") && sprockets_version > Gem::Version.new("4.0.0.beta4")
+      msg << "If you have this file in your project\n"
+      msg << "try upgrading to Sprockets 4.0.0.beta7 or later:\n"
+      msg << "https://github.com/rails/sprockets/pull/547\n"
+    end
+
+    error msg
   end
 
-  def purge_bundler_cache
-    instrument "ruby.purge_bundler_cache" do
-      FileUtils.rm_rf(bundler_cache)
-      cache.clear bundler_cache
-      # need to reinstall language pack gems
-      install_bundler_in_app
+  def self.load_bundler_cache(cache:, metadata:, stack:, bundler_cache:, bundler_version:, bundler:, io:, new_app:, ruby_version:)
+    cache.load "vendor"
+
+    full_ruby_version = `ruby -v 2>/dev/null`.strip
+    ruby_version_cache = "ruby_version"
+    stack_cache = "stack"
+
+    # bundle clean does not remove binstubs
+    FileUtils.rm_rf("vendor/bundler/bin")
+
+    old_stack = metadata.try_read(stack_cache)
+
+    stack_change = old_stack != stack
+    convert_stack = bundler_cache.old?
+    bundler_cache.convert_stack(stack_change) if convert_stack
+    if !new_app && stack_change
+      io.puts "Purging Cache. Changing stack from #{old_stack} to #{stack}"
+      purge_bundler_cache(bundler_cache: bundler_cache, stack: old_stack, ruby_version: ruby_version, bundler: bundler)
+    elsif !new_app && !convert_stack
+      bundler_cache.load
+    end
+
+    if (bundler_cache.exists? || bundler_cache.old?) &&
+        metadata.exists?(ruby_version_cache) &&
+        full_ruby_version != metadata.read(ruby_version_cache).strip
+      io.puts "Ruby version change detected. Clearing bundler cache."
+      io.puts "Old: #{metadata.read(ruby_version_cache).strip}"
+      io.puts "New: #{full_ruby_version}"
+      purge_bundler_cache(bundler_cache: bundler_cache, stack: nil, ruby_version: ruby_version, bundler: bundler)
+    end
+
+    metadata.write(ruby_version_cache, full_ruby_version)
+    metadata.write("buildpack_version", BUILDPACK_VERSION)
+    metadata.write("bundler_version", bundler_version)
+    metadata.write("rubygems_version", `gem -v 2>/dev/null`.strip)
+    metadata.write(stack_cache, stack)
+  end
+
+  def self.purge_bundler_cache(bundler_cache:, ruby_version:, bundler:, stack: nil)
+    bundler_cache.clear(stack)
+    # need to reinstall bundler
+    bundler.install
+  end
+
+  def purge_bundler_cache(stack = nil)
+    @bundler_cache.clear(stack)
+    bundler.install
+  end
+
+  # writes ERB based database.yml for Rails. The database.yml uses the DATABASE_URL from the environment during runtime.
+  def create_database_yml
+    return false unless File.directory?("config")
+    return false if bundler.has_gem?("activerecord") && bundler.gem_version("activerecord") >= Gem::Version.new("4.1.0.beta1")
+
+    topic("Writing config/database.yml to read from DATABASE_URL")
+    File.open("config/database.yml", "w") do |file|
+      file.puts <<~DATABASE_YML
+        <%
+
+        require 'cgi'
+        require 'uri'
+
+        begin
+          uri = URI.parse(ENV["DATABASE_URL"])
+        rescue URI::InvalidURIError
+          raise "Invalid DATABASE_URL"
+        end
+
+        raise "No RACK_ENV or RAILS_ENV found" unless ENV["RAILS_ENV"] || ENV["RACK_ENV"]
+
+        def attribute(name, value, force_string = false)
+          if value
+            value_string =
+              if force_string
+                '"' + value + '"'
+              else
+                value
+              end
+            "\#{name}: \#{value_string}"
+          else
+            ""
+          end
+        end
+
+        adapter = uri.scheme
+        adapter = "postgresql" if adapter == "postgres"
+
+        database = (uri.path || "").split("/")[1]
+
+        username = uri.user
+        password = uri.password
+
+        host = uri.host
+        port = uri.port
+
+        params = CGI.parse(uri.query || "")
+
+        %>
+
+        <%= ENV["RAILS_ENV"] || ENV["RACK_ENV"] %>:
+          <%= attribute "adapter",  adapter %>
+          <%= attribute "database", database %>
+          <%= attribute "username", username %>
+          <%= attribute "password", password, true %>
+          <%= attribute "host",     host %>
+          <%= attribute "port",     port %>
+
+        <% params.each do |key, value| %>
+          <%= key %>: <%= value.first %>
+        <% end %>
+      DATABASE_YML
     end
   end
 end
diff --git a/lib/language_pack/ruby_version.rb b/lib/language_pack/ruby_version.rb
index deee8371a..842b60b3a 100644
--- a/lib/language_pack/ruby_version.rb
+++ b/lib/language_pack/ruby_version.rb
@@ -1,48 +1,115 @@
-require "language_pack/shell_helpers"
+require "language_pack/shell_helpers" # Holds BuildpackError
 
 module LanguagePack
   class RubyVersion
-    class BadVersionError < StandardError
+    class BadVersionError < BuildpackError
       def initialize(output = "")
-        msg = "Can not parse Ruby Version:\n"
-        msg << "Valid versions listed on: https://devcenter.heroku.com/articles/ruby-support\n"
+        msg = ""
         msg << output
-        super msg
+        msg << "Can not parse Ruby Version:\n"
+        msg << "Valid versions listed on: https://devcenter.heroku.com/articles/ruby-support\n"
+        super(msg)
       end
     end
 
-    DEFAULT_VERSION_NUMBER = "2.0.0"
-    DEFAULT_VERSION        = "ruby-#{DEFAULT_VERSION_NUMBER}"
-    LEGACY_VERSION_NUMBER  = "1.9.2"
-    LEGACY_VERSION         = "ruby-#{LEGACY_VERSION_NUMBER}"
-    RUBY_VERSION_REGEX     = %r{
-        (?<ruby_version>\d+\.\d+\.\d+){0}
-        (?<patchlevel>p\d+){0}
-        (?<engine>\w+){0}
-        (?<engine_version>.+){0}
+    BOOTSTRAP_VERSION_NUMBER = "3.3.9".freeze
+    DEFAULT_VERSION_NUMBER = "3.3.9".freeze
+    DEFAULT_VERSION = "ruby-#{DEFAULT_VERSION_NUMBER}".freeze
+
+    # String formatted `<major>.<minor>.<patch>` for Ruby and JRuby
+    attr_reader :ruby_version,
+      # `engine` is `:ruby` or `:jruby`
+      :engine,
+      # `engine_version` is the Jruby version or for MRI it is the same as `ruby_version`
+      # i.e. `<major>.<minor>.<patch>`
+      :engine_version,
+      # Pre-release identifier e.g. "rc1", "preview2", or nil for stable releases
+      :pre
+
+    def self.from_gemfile_lock(ruby:, last_version: nil)
+      if ruby.empty?
+        default(last_version: last_version)
+      else
+        new(
+          pre: ruby.pre,
+          engine: ruby.engine,
+          default: false,
+          ruby_version: ruby.ruby_version,
+          engine_version: ruby.engine_version
+        )
+      end
+    end
 
-        ruby-\g<ruby_version>(-\g<patchlevel>)?(-\g<engine>-\g<engine_version>)?
-      }x
+    def self.default(last_version:)
+      ruby_version = last_version&.split("-")&.last || DEFAULT_VERSION_NUMBER
+      new(
+        pre: nil,
+        engine: :ruby,
+        default: true,
+        ruby_version: ruby_version,
+        engine_version: ruby_version
+      )
+    end
 
-    attr_reader :set, :version, :version_without_patchlevel, :patchlevel, :engine, :ruby_version, :engine_version
-    include LanguagePack::ShellHelpers
+    def initialize(
+      pre:,
+      engine:,
+      default:,
+      ruby_version:,
+      engine_version:
+    )
+      @pre = pre
+      @engine = engine
+      @default = default
+      @ruby_version = ruby_version
+      @engine_version = engine_version
+    end
 
-    def initialize(bundler, app = {})
-      @set          = nil
-      @bundler      = bundler
-      @app          = app
-      set_version
-      parse_version
+    # Also used as for metrics to track unique installs
+    # i.e. `ruby-3.4.2`
+    def version_for_download
+      if @engine == :jruby
+        "ruby-#{ruby_version}-jruby-#{engine_version}"
+      else
+        "ruby-#{engine_version_full}"
+      end
+    end
+
+    # Full qualifier for the version including pre-release information
+    # i.e. `3.5.0.preview1` or `3.5.0` or `3.5.0.rc1` for ruby
+    # i.e. `9.4.9.0` for jruby
+    def engine_version_full
+      if @engine == :jruby
+        engine_version
+      elsif @pre
+        "#{engine_version}.#{@pre}"
+      else
+        engine_version.to_s
+      end
+    end
 
-      @version_without_patchlevel = @version.sub(/-p[\d]+/, '')
+    # Ruby versioned bundler directory
+    #
+    # When installing gems via `BUNDLE_DEPLOYMENT=1 bundle install`, they're installed into a versioned directory based on the ruby version.
+    #
+    # This becomes the location of GEM_PATH on disk https://www.schneems.com/2014/04/15/gem-path.html.
+    # - Executables are at bundler_directory.join("bin")
+    # - Gems are at bundler_directory.join("gems")
+    #
+    # For example:
+    #
+    # - Ruby 3.4.7 would be "vendor/bundle/ruby/3.4.0"
+    # - JRuby 9.4.14.0 would be "vendor/bundle/jruby/3.1.0" (As it implements Ruby 3.1.7 spec)
+    def bundler_directory
+      "vendor/bundle/#{engine}/#{major}.#{minor}.0"
     end
 
-    def rake_is_vendored?
-      Gem::Version.new(self.ruby_version) >= Gem::Version.new("1.9")
+    def file_name
+      "#{version_for_download}.tgz"
     end
 
     def default?
-      @version == none
+      @default
     end
 
     # determine if we're using jruby
@@ -51,18 +118,6 @@ def jruby?
       engine == :jruby
     end
 
-    # determine if we're using rbx
-    # @return [Boolean] true if we are and false if we aren't
-    def rbx?
-      engine == :rbx
-    end
-
-    # determines if a build ruby is required
-    # @return [Boolean] true if a build ruby is required
-    def build?
-      engine == :ruby && %w(1.8.7 1.9.2).include?(ruby_version)
-    end
-
     # convert to a Gemfile ruby DSL incantation
     # @return [String] the string representation of the Gemfile ruby DSL
     def to_gemfile
@@ -73,52 +128,32 @@ def to_gemfile
       end
     end
 
-    private
-    def gemfile
-      ruby_version = @bundler.ruby_version
-      return "" unless ruby_version
+    def major
+      @ruby_version.split(".")[0].to_i
+    end
 
-      parts = [
-        "ruby",
-        ruby_version.version
-      ]
-      parts << "p#{ruby_version.patchlevel}" if ruby_version.patchlevel
-      unless ruby_version.engine == "ruby"
-        parts << ruby_version.engine
-        parts << ruby_version.engine_version
-      end
+    def minor
+      @ruby_version.split(".")[1].to_i
+    end
 
-      parts.compact.join("-")
+    def patch
+      @ruby_version.split(".")[2].to_i
     end
 
-    def none
-      if @app[:is_new]
-        DEFAULT_VERSION
-      elsif @app[:last_version]
-        @app[:last_version]
-      else
-        LEGACY_VERSION
-      end
+    # Returns the next logical version in the minor series
+    # for example if the current ruby version is
+    # `ruby-2.3.1` then then `next_logical_version(1)`
+    # will produce `ruby-2.3.2`.
+    def next_logical_version(increment = 1)
+      "ruby-#{major}.#{minor}.#{patch + increment}"
     end
 
-    def set_version
-      bundler_output = gemfile
-      if bundler_output.empty?
-        @set     = false
-        @version = none
-      else
-        @set     = :gemfile
-        @version = gemfile
-      end
+    def next_minor_version(increment = 1)
+      "ruby-#{major}.#{minor + increment}.0"
     end
 
-    def parse_version
-      md = RUBY_VERSION_REGEX.match(version)
-      raise BadVersionError.new("'#{version}' is not valid") unless md
-      @ruby_version   = md[:ruby_version]
-      @patchlevel     = md[:patchlevel]
-      @engine_version = md[:engine_version] || @ruby_version
-      @engine         = (md[:engine]        || :ruby).to_sym
+    def next_major_version(increment = 1)
+      "ruby-#{major + increment}.0.0"
     end
   end
 end
diff --git a/lib/language_pack/shell_helpers.rb b/lib/language_pack/shell_helpers.rb
index 3a16d33f1..13248e01f 100644
--- a/lib/language_pack/shell_helpers.rb
+++ b/lib/language_pack/shell_helpers.rb
@@ -1,4 +1,8 @@
 require "shellwords"
+require "timeout"
+
+class BuildpackError < StandardError
+end
 
 class NoShellEscape < String
   def shellescape
@@ -9,6 +13,11 @@ def shellescape
 module LanguagePack
   module ShellHelpers
     @@user_env_hash = {}
+    @@warnings = []
+
+    def warnings
+      @@warnings
+    end
 
     def self.user_env_hash
       @@user_env_hash
@@ -23,43 +32,64 @@ def env(var)
     end
 
     def self.blacklist?(key)
-      %w(PATH GEM_PATH GEM_HOME GIT_DIR).include?(key)
+      %w[PATH GEM_PATH GEM_HOME GIT_DIR JRUBY_OPTS JAVA_OPTS JAVA_TOOL_OPTIONS RUBYOPT].include?(key)
     end
 
     def self.initialize_env(path)
-      env_dir = Pathname.new("#{path}")
+      env_dir = Pathname.new(path.to_s)
       if env_dir.exist? && env_dir.directory?
         env_dir.each_child do |file|
-          key   = file.basename.to_s
+          key = file.basename.to_s
           value = file.read.strip
           user_env_hash[key] = value unless blacklist?(key)
         end
       end
     end
 
-    # display error message and stop the build process
-    # @param [String] error message
-    def error(message)
+    # Should only be used once in the top level script
+    # for example $ bin/support/ruby_compile
+    def self.display_error_and_exit(e)
+      Kernel.puts "\e[1m\e[31m" # Bold Red
       Kernel.puts " !"
-      message.split("\n").each do |line|
+      e.message.split("\n").each do |line|
         Kernel.puts " !     #{line.strip}"
       end
-      Kernel.puts " !"
-      log "exit", :error => message if respond_to?(:log)
-      exit 1
+      Kernel.puts " !\e[0m"
+      if e.is_a?(BuildpackError)
+        exit 1
+      else
+        raise e
+      end
     end
 
+    # run a shell command (deferring to #run), and raise an error if it fails
+    # @param [String] command to be run
+    # @return [String] result of #run
+    # @option options [Error] :error_class Class of error to raise, defaults to Standard Error
+    # @option options [Integer] :max_attempts Number of times to attempt command before raising
     def run!(command, options = {})
-      result = run(command, options)
-      error("Command: '#{command}' failed unexpectedly:\n#{result}") unless $?.success?
-      return result
+      max_attempts = options[:max_attempts] || 1
+      error_class = options[:error_class] || StandardError
+      silent = options.key?(:silent) ? options[:silent] : false
+      max_attempts.times do |attempt_number|
+        result = run(command, options)
+        if $?.success?
+          return result
+        end
+        if attempt_number == max_attempts - 1
+          raise error_class, "Command: '#{command}' failed unexpectedly:\n#{result}"
+        else
+          next if silent
+          puts "Command: '#{command}' failed on attempt #{attempt_number + 1} of #{max_attempts}."
+        end
+      end
     end
 
     # doesn't do any special piping. stderr won't be redirected.
     # @param [String] command to be run
     # @return [String] output of stdout
     def run_no_pipe(command, options = {})
-      run(command, options.merge({:out => ""}))
+      run(command, options.merge({out: ""}))
     end
 
     # run a shell command and pipe stderr to stdout
@@ -68,70 +98,175 @@ def run_no_pipe(command, options = {})
     # @option options [Hash] :env explicit environment to run command in
     # @option options [Boolean] :user_env whether or not a user's environment variables will be loaded
     def run(command, options = {})
-      %x{ #{command_options_to_string(command, options)} }
-    end
-
-    # run a shell command and pipe stderr to /dev/null
-    # @param [String] command to be run
-    # @return [String] output of stdout
-    def run_stdout(command, options = {})
-      options[:out] ||= '2>/dev/null'
-      run(command, options)
+      `#{command_options_to_string(command, options)}`
     end
 
     def command_options_to_string(command, options)
       options[:env] ||= {}
       options[:out] ||= "2>&1"
       options[:env] = user_env_hash.merge(options[:env]) if options[:user_env]
-      env = options[:env].map {|key, value| "#{key.shellescape}=#{value.shellescape}" }.join(" ")
+      env = options[:env].map { |key, value| "#{key.shellescape}=#{value.shellescape}" }.join(" ")
       "/usr/bin/env #{env} bash -c #{command.shellescape} #{options[:out]} "
     end
 
+    # Class for running process spawn with a timeout
+    #
+    # Example:
+    #
+    #   spawn = ProcessSpawn.new("echo 'hello'")
+    #   spawn.success? # => true
+    #   spawn.timeout? # => false
+    #
+    # If you want to get the output of the process, you will need to pass
+    # in a file:
+    #
+    #   spawn = ProcessSpawn.new("echo 'hello'", file: "hello.txt")
+    #   spawn.success? # => true
+    #   spawn.output   # => "hello"
+    #
+    # The main benefit of using a file is that even if the command fails
+    # or times out, there will still be partial results in the output file.
+    #
+    # To add a timeout, instantiate pass in a hash with a `timeout` key
+    # in seconds:
+    #
+    #   spawn = ProcessSpawn.new("sleep 10", timeout: 4)
+    #   spawn.success? # => false
+    #   spawn.timeout? # => true
+    #
+    class ProcessSpawn
+      include ShellHelpers
+
+      def initialize(command, options = {})
+        @timeout_value = options.delete(:timeout)
+        @file = options.delete(:file)
+        if @file
+          raise "Cannot specify :file, and :out" if options[:out]
+          @file = Pathname.new(@file)
+          @file.dirname.mkpath
+          FileUtils.touch(@file)
+
+          options[:out] = ">> #{@file} 2>&1"
+        end
+
+        @command = command_options_to_string(command, options)
+        @did_time_out = false
+        @success = false
+      end
+
+      def output
+        raise "no file name given" if @file.nil?
+        exec_once
+        @file.read.encode("UTF-8", invalid: :replace)
+      end
+
+      def timeout?
+        exec_once
+        @did_time_out
+      end
+
+      def success?
+        exec_once
+        @success
+      end
+
+      private
+
+      def exec_once
+        return if @exec_once
+        @exec_once = true
+        wait_with_timeout
+        true
+      end
+
+      def wait_with_timeout
+        pid = Process.spawn(@command)
+        Timeout.timeout(@timeout_value) do
+          Process.wait(pid)
+          @success = $?.success?
+        end
+      rescue Timeout::Error
+        Process.kill("SIGKILL", pid)
+        @did_time_out = true
+        @success = false
+      end
+    end
+
     # run a shell command and stream the output
     # @param [String] command to be run
     def pipe(command, options = {})
-      output = ""
+      output = options[:buffer] || ""
+      silent = options[:silent]
+      # self.puts uses the method defined in this file
+      output_object = options[:output_object] || self
       IO.popen(command_options_to_string(command, options)) do |io|
         until io.eof?
           buffer = io.gets
           output << buffer
-          puts buffer
+          output_object.puts(buffer) unless silent
         end
       end
 
       output
     end
 
-    # display a topic message
-    # (denoted by ----->)
-    # @param [String] topic message to be displayed
-    def topic(message)
-      Kernel.puts "-----> #{message}"
-      $stdout.flush
-    end
+    module BuildOutput
+      # display a topic message
+      # (denoted by ----->)
+      # @param [String] topic message to be displayed
+      def topic(message)
+        Kernel.puts "-----> #{message}"
+        $stdout.flush
+      end
+
+      # display a message in line
+      # (indented by 6 spaces)
+      # @param [String] message to be displayed
+      def puts(message)
+        message.to_s.each_line do |line|
+          if line.end_with?("\n".freeze)
+            print "       #{line}"
+          else
+            print "       #{line}\n"
+          end
+        end
 
-    # display a message in line
-    # (indented by 6 spaces)
-    # @param [String] message to be displayed
-    def puts(message)
-      message.split("\n").each do |line|
-        super "       #{line.strip}"
+        $stdout.flush
+      rescue ArgumentError, Encoding::CompatibilityError => e
+        error_message = e.message
+        raise e if !/invalid byte sequence/.match?(error_message)
+
+        error_message << "\n       Invalid string: #{message}"
+        raise e, error_message
       end
-      $stdout.flush
-    end
 
-    def warn(message, options = {})
-      if options.key?(:inline) ? options[:inline] : false
-        topic "Warning:"
-        puts message
+      def error(message)
+        raise BuildpackError, message
+      end
+
+      # Requires a self#warnings method that returns an array
+      def warn(message, options = {})
+        if options.key?(:inline) ? options[:inline] : false
+          Kernel.puts ""
+          Kernel.puts "\e[1m\e[33m###### WARNING:\e[0m" # Bold yellow
+          Kernel.puts ""
+          puts message
+          Kernel.puts ""
+        end
+        warnings << message
       end
-      @warnings ||= []
-      @warnings << message
     end
+    include BuildOutput
+
+    # Prints output and stores warnings
+    class WarnIO
+      include BuildOutput
+
+      def initialize
+        @warnings = []
+      end
 
-    def deprecate(message)
-      @deprecations ||= []
-      @deprecations << message
+      attr_reader :warnings
     end
 
     def noshellescape(string)
diff --git a/lib/language_pack/test.rb b/lib/language_pack/test.rb
new file mode 100644
index 000000000..0f8f7eb07
--- /dev/null
+++ b/lib/language_pack/test.rb
@@ -0,0 +1,10 @@
+require "language_pack"
+
+module LanguagePack::Test
+end
+
+# Behavior changes for the test pack work by opening existing language_pack
+# classes and over-writing their behavior to extend test functionality
+require "language_pack/test/ruby"
+require "language_pack/test/rails2"
+require "language_pack/test/rails7"
diff --git a/lib/language_pack/test/rails2.rb b/lib/language_pack/test/rails2.rb
new file mode 100644
index 000000000..b61c98a70
--- /dev/null
+++ b/lib/language_pack/test/rails2.rb
@@ -0,0 +1,62 @@
+# Opens up the class of the Rails2 language pack and
+# overwrites methods defined in `language_pack/test/ruby.rb`
+class LanguagePack::Rails2
+  def prepare_tests
+    # need to clear db:create before db:schema:load_if_ruby gets called by super
+    topic "Clearing #{db_test_tasks_to_clear.join(" ")} rake tasks"
+    clear_db_test_tasks
+    super
+  end
+
+  def db_test_tasks_to_clear
+    # db:test:purge is called by everything in the db:test namespace
+    # db:create is called by :db:schema:load_if_ruby
+    # db:structure:dump is not needed for tests, but breaks Rails 3.2 db:structure:load on Heroku
+    ["db:test:purge", "db:create", "db:structure:dump"]
+  end
+
+  # rails test runner + rspec depend on db:test:purge which drops/creates a db which doesn't work on Heroku's DB plans
+  def clear_db_test_tasks
+    FileUtils.mkdir_p "lib/tasks"
+    File.open("lib/tasks/heroku_clear_tasks.rake", "w") do |file|
+      file.puts "# rubocop:disable all"
+      content = db_test_tasks_to_clear.map do |task_name|
+        <<~FILE
+          if Rake::Task.task_defined?('#{task_name}')
+            Rake::Task['#{task_name}'].clear
+            task '#{task_name}' do
+            end
+          end
+        FILE
+      end.join("\n")
+      file.print content
+      file.puts "# rubocop:enable all"
+    end
+  end
+
+  def db_prepare_test_rake_tasks
+    schema_load = rake.task("db:schema:load_if_ruby")
+    structure_load = rake.task("db:structure:load_if_sql")
+    db_migrate = rake.task("db:migrate")
+
+    return [] if db_migrate.not_defined?
+
+    if schema_load.not_defined? && structure_load.not_defined?
+      result = detect_schema_format
+      case result.lines.last.strip
+      when "ruby"
+        schema_load = rake.task("db:schema:load")
+      when "sql" # currently not a possible edge case, we think
+        structure_load = rake.task("db:structure:load")
+      else
+        puts "Could not determine schema/structure from `ActiveRecord::Base.schema_format`:\n#{result}"
+      end
+    end
+
+    [schema_load, structure_load, db_migrate]
+  end
+
+  def detect_schema_format
+    run("rails runner 'puts ActiveRecord::Base.schema_format'", user_env: true)
+  end
+end
diff --git a/lib/language_pack/test/rails7.rb b/lib/language_pack/test/rails7.rb
new file mode 100644
index 000000000..97fd20ea8
--- /dev/null
+++ b/lib/language_pack/test/rails7.rb
@@ -0,0 +1,9 @@
+# Opens up the class of the Rails7 language pack and
+# overwrites methods defined in `language_pack/test/ruby.rb` or `language_pack/test/rails2.rb`
+class LanguagePack::Rails7
+  # Rails removed the db:schema:load_if_ruby and `db:structure:load_if_sql` tasks
+  # they've been replaced by `db:schema:load` instead
+  def db_prepare_test_rake_tasks
+    ["db:schema:load", "db:migrate"].map { |name| rake.task(name) }
+  end
+end
diff --git a/lib/language_pack/test/ruby.rb b/lib/language_pack/test/ruby.rb
new file mode 100644
index 000000000..bf0277889
--- /dev/null
+++ b/lib/language_pack/test/ruby.rb
@@ -0,0 +1,41 @@
+# Opens up the class of the Ruby language pack and
+# overwrites methods defined in `language_pack/ruby.rb`
+#
+# Other "test packs" futher extend this behavior by hooking into
+# methods or over writing methods defined here.
+class LanguagePack::Ruby
+  def compile
+    @outdated_version_check = LanguagePack::Helpers::OutdatedRubyVersion.new(
+      current_ruby_version: ruby_version,
+      fetcher: LanguagePack::Installers::HerokuRubyInstaller.fetcher(amd_only_stacks: AMD_ONLY_STACKS, stack: stack, arch: @arch)
+    ).call
+    @warn_io.warnings.each { |warning| warnings << warning }
+    post_bundler(ruby_version: @ruby_version, app_path: app_path)
+    create_database_yml
+    install_binaries
+    prepare_tests
+    default_config_vars = self.class.default_config_vars(metadata: @metadata, ruby_version: @ruby_version, bundler: bundler, environment_name: environment_name)
+    setup_profiled(ruby_layer_path: "$HOME", gem_layer_path: "$HOME", ruby_version: @ruby_version, default_config_vars: default_config_vars, report: @report) # $HOME is set to /app at run time
+    setup_export(app_path: app_path, ruby_version: @ruby_version, default_config_vars: default_config_vars)
+    super
+  end
+
+  def db_prepare_test_rake_tasks
+    ["db:schema:load", "db:migrate"].map { |name| rake.task(name) }
+  end
+
+  def prepare_tests
+    rake_tasks = db_prepare_test_rake_tasks.select(&:is_defined?)
+    return true if rake_tasks.empty?
+
+    topic "Preparing test database"
+    rake_tasks.each do |rake_task|
+      rake_task.invoke(env: rake_env)
+      if rake_task.success?
+        puts "#{rake_task.task} completed (#{"%.2f" % rake_task.time}s)"
+      else
+        error "Could not prepare database for test"
+      end
+    end
+  end
+end
diff --git a/lib/language_pack/version.rb b/lib/language_pack/version.rb
index a94f79c8a..9d1d34c5c 100644
--- a/lib/language_pack/version.rb
+++ b/lib/language_pack/version.rb
@@ -1,8 +1,7 @@
 require "language_pack/base"
 
-# This file is automatically generated by rake
 module LanguagePack
   class LanguagePack::Base
-    BUILDPACK_VERSION = "v108"
+    BUILDPACK_VERSION = "v334"
   end
 end
diff --git a/lib/rake/deploy_check.rb b/lib/rake/deploy_check.rb
new file mode 100644
index 000000000..00cd8c080
--- /dev/null
+++ b/lib/rake/deploy_check.rb
@@ -0,0 +1,131 @@
+# A class for checking if a local copy of a repo can be tagged for a deploy
+#
+# Example:
+#
+#   deploy = DeployCheck.new(github: "heroku/heroku-buildpack-ruby")
+#   deploy.check! # Checks that current main branch matches what's on github
+#
+# It also can pull tag versions and determine the next sequential version automatically:
+#
+#   deploy.next_version # => "v999" # Assuming the last version was v998
+#
+# It can determine status of tags
+#
+#   deploy.push_tags? #=> false
+#
+class DeployCheck
+  attr_reader :github_url
+
+  def initialize(github:, next_version: ENV["RELEASE_VERSION"])
+    @github = github
+    @github_url = "https://github.com/#{github}"
+    @next_version = next_version
+    @remote_tag_array = nil
+  end
+
+  def check!
+    check_version!
+    check_unstaged!
+    check_branch!
+    check_changelog!
+    check_sync!
+  end
+
+  def push_tag?
+    return true if !tag_exists_on_remote?
+    return false if remote_tag_matches?
+
+    # Tag exists, but is not the same commit, raise an error
+    raise <<~EOM
+      The tag you're pushing (#{next_version}) to #{@github} already exists and does not have the same SHA.
+      You must resolve this manually.
+    EOM
+  end
+
+  # Returns tuthy value if the remote contains the next version already
+  def tag_exists_on_remote?
+    remote_tag_array.include?(next_version)
+  end
+
+  # Returns a truthy value if the remote tag SHA matches the current local sha
+  def remote_tag_matches?(remote_sha: remote_commit_sha(next_version), local_sha: local_commit_sha)
+    remote_sha == local_sha
+  end
+
+  # Raises an error if there are unstaged modifications
+  def check_unstaged!
+    run!("git diff --quiet HEAD") do
+      raise "Must have all changes committed. There are unstaged commits locally"
+    end
+  end
+
+  # Raises an error if not on the designated branch
+  def check_branch!(name = "main")
+    out = run("git rev-parse --abbrev-ref HEAD")
+    raise "Must be on main branch. Branch: #{out}" unless out == name
+  end
+
+  # Raises an error if the changelog does not have an entry with the designated version
+  def check_changelog!
+    if !File.read("CHANGELOG.md").include?("## [#{next_version}]")
+      raise "Expected CHANGELOG.md to include [#{next_version}] but it did not"
+    end
+  end
+
+  # Raises an error if the local sha does not match the remote sha
+  def check_sync!(local_sha: local_commit_sha, remote_sha: remote_commit_sha)
+    return if remote_sha == local_sha
+
+    raise <<~EOM
+      Must be in-sync with #{@github}. Local commit: #{local_sha.inspect} #{@github}: #{remote_sha.inspect}
+      "Make sure that you've pulled: `git pull --rebase #{@github_url} main`
+    EOM
+  end
+
+  def check_version!
+    version = next_version
+
+    raise "Must look like a version: #{version}. Must start with `v` and include only digits" unless version.match?(/^v\d+$/)
+  end
+
+  def local_commit_sha
+    run!("git rev-parse HEAD")
+  end
+
+  def remote_commit_sha(branch_or_tag = "main")
+    run!("git ls-remote #{@github_url} #{branch_or_tag}").split("\t").first
+  end
+
+  def run(cmd)
+    `#{cmd}`.strip
+  end
+
+  def next_version
+    @next_version || "v#{next_version_number}"
+  end
+
+  def remote_tag_array
+    @remote_tag_array ||= begin
+      cmd = +""
+      cmd << "git ls-remote --tags #{@github_url}"
+      cmd << "| awk '{print $2}' | cut -d '/' -f 3 | cut -d '^' -f 1"
+      run!(cmd).each_line.map(&:strip).select { |line| line.strip.match?(/^v\d+$/) } # https://rubular.com/r/8eFB9r8nOVrM7H
+    end
+  end
+
+  private def next_version_number
+    integer_tag_array = remote_tag_array.map { |line| line.sub(/^v/, "").to_i }.sort # Ascending order
+    integer_tag_array.last.next
+  end
+
+  def run!(cmd)
+    out = run(cmd)
+    return out if $?.success?
+
+    if block_given?
+      yield out, $?
+    else
+      raise "Command #{cmd} expected to return successfully did not: #{out.inspect}"
+    end
+  end
+end
diff --git a/spec/bugs_spec.rb b/spec/bugs_spec.rb
deleted file mode 100644
index 5bd177863..000000000
--- a/spec/bugs_spec.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-require_relative 'spec_helper'
-
-describe "Bugs" do
-  context "MRI 1.8.7" do
-    it "should install nokogiri" do
-      Hatchet::Runner.new("mri_187_nokogiri").deploy do |app|
-        expect(app.output).to match("Installing nokogiri")
-        expect(app.output).to match("Your bundle is complete!")
-      end
-    end
-  end
-
-  it "nokogiri should use the system libxml2" do
-    Hatchet::Runner.new("nokogiri_160").deploy do |app|
-      expect(app.output).to match("nokogiri")
-      expect(app.run("bundle exec nokogiri -v")).not_to include("WARNING: Nokogiri was built against LibXML version")
-    end
-  end
-end
diff --git a/spec/default_cache_spec.rb b/spec/default_cache_spec.rb
deleted file mode 100644
index b83c0ff90..000000000
--- a/spec/default_cache_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require 'spec_helper'
-
-describe "Default Cache" do
-  it "gets loaded successfully" do
-    Hatchet::Runner.new("default_ruby").deploy do |app|
-      expect(app.output).to match("loading default bundler cache")
-    end
-  end
-end
-
diff --git a/spec/fixtures/invalid_encoding.log b/spec/fixtures/invalid_encoding.log
new file mode 100644
index 000000000..16047e6e6
--- /dev/null
+++ b/spec/fixtures/invalid_encoding.log
@@ -0,0 +1 @@
+ACENOCUMAROL,AZECAR,1 MG 30 COMPRIMIDOS, ññóénñ
diff --git a/spec/fixtures/windows_lockfile/Gemfile b/spec/fixtures/windows_lockfile/Gemfile
new file mode 100644
index 000000000..e69de29bb
diff --git a/spec/fixtures/windows_lockfile/Gemfile.lock b/spec/fixtures/windows_lockfile/Gemfile.lock
new file mode 100644
index 000000000..4d0fc2948
--- /dev/null
+++ b/spec/fixtures/windows_lockfile/Gemfile.lock
@@ -0,0 +1,2 @@
+BUNDLED WITH
+   2.0.2
diff --git a/spec/gem_detect_errors_spec.rb b/spec/gem_detect_errors_spec.rb
deleted file mode 100644
index 5e311c92f..000000000
--- a/spec/gem_detect_errors_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require 'spec_helper'
-
-describe "Raise errors on specific gems" do
-  it "should should raise on sqlite3" do
-    Hatchet::Runner.new("sqlite3_gemfile", allow_failure: true).deploy do |app|
-      expect(app).not_to be_deployed
-      expect(app.output).to include("Detected sqlite3 gem which is not supported")
-      expect(app.output).to include("devcenter.heroku.com/articles/sqlite3")
-    end
-  end
-end
-
diff --git a/spec/hatchet/bugs_spec.rb b/spec/hatchet/bugs_spec.rb
new file mode 100644
index 000000000..8e2a80244
--- /dev/null
+++ b/spec/hatchet/bugs_spec.rb
@@ -0,0 +1,48 @@
+require_relative "../spec_helper"
+
+describe "Bugs" do
+  context "database connections" do
+    it "fails with better error message" do
+      Hatchet::Runner.new("ruby-getting-started", allow_failure: true).tap do |app|
+        app.before_deploy do
+          Pathname("Rakefile").write(<<~EOM)
+            require 'bundler'
+            Bundler.require(:default)
+
+            require 'active_record'
+
+            task "assets:precompile" do
+              # Try to connect to a database that doesn't exist yet
+              ActiveRecord::Base.establish_connection
+              ActiveRecord::Base.connection.execute("")
+            end
+          EOM
+        end
+
+        app.deploy do
+          expect(app.output).to match("https://devcenter.heroku.com/articles/pre-provision-database")
+        end
+      end
+    end
+
+    it "does not generate an incorrect DATABASE_URL if adapter is not known" do
+      Hatchet::Runner.new("rails_8_1_trilogy_db_minimal").tap do |app|
+        app.deploy do
+          # Works
+        end
+      end
+    end
+  end
+
+  it "detect fails when no Gemfile is present" do
+    Hatchet::Runner.new("default_ruby", allow_failure: true).tap do |app|
+      app.before_deploy do
+        FileUtils.rm("Gemfile")
+      end
+      app.deploy do |app|
+        expect(app.output).to include("A Ruby app on Heroku must have a 'Gemfile' and 'Gemfile.lock' in the root directory of its source code.")
+        expect(app).not_to be_deployed
+      end
+    end
+  end
+end
diff --git a/spec/hatchet/buildpack_spec.rb b/spec/hatchet/buildpack_spec.rb
new file mode 100644
index 000000000..dac1087a1
--- /dev/null
+++ b/spec/hatchet/buildpack_spec.rb
@@ -0,0 +1,14 @@
+require_relative "../spec_helper"
+
+describe "Buildpack internals" do
+  it "handles PATH with a newline in it correctly" do
+    buildpacks = [
+      "https://github.com/sharpstone/export_path_with_newlines_buildpack",
+      :default,
+      "https://github.com/heroku/null-buildpack"
+    ]
+    Hatchet::Runner.new("default_ruby", buildpacks: buildpacks).deploy do |app|
+      expect(app.output).to_not match("No such file or directory")
+    end
+  end
+end
diff --git a/spec/hatchet/bundler_spec.rb b/spec/hatchet/bundler_spec.rb
new file mode 100644
index 000000000..41f9f7b50
--- /dev/null
+++ b/spec/hatchet/bundler_spec.rb
@@ -0,0 +1,12 @@
+require "spec_helper"
+
+describe "Bundler" do
+  it "can be configured with BUNDLE_WITHOUT env var with spaces in it" do
+    Hatchet::Runner.new("default_ruby", config: {"BUNDLE_WITHOUT" => "foo bar baz"}).tap do |app|
+      app.deploy do
+        expect(app.output).to match("BUNDLE_WITHOUT='foo:bar:baz'")
+        expect(app.output).to match("Your BUNDLE_WITHOUT contains a space")
+      end
+    end
+  end
+end
diff --git a/spec/hatchet/ci_spec.rb b/spec/hatchet/ci_spec.rb
new file mode 100644
index 000000000..8661661c5
--- /dev/null
+++ b/spec/hatchet/ci_spec.rb
@@ -0,0 +1,280 @@
+require "spec_helper"
+
+describe "CI" do
+  it "Does not cause the double ruby rainbow bug" do
+    Hatchet::Runner.new("heroku-ci-json-example").run_ci do |test_run|
+      expect(test_run.status).to eq(:succeeded)
+
+      install_bundler_count = test_run.output.scan("Installing bundler").count
+      expect(install_bundler_count).to eq(1), "Expected output to only install bundler once but was found #{install_bundler_count} times. output:\n#{test_run.output}"
+    end
+  end
+
+  it "Works with Rails: ruby schema apps" do
+    Hatchet::Runner.new("rails_8_ruby_schema", stack: "heroku-24").tap do |app|
+      app.before_deploy do
+        Pathname("app.json").write(<<~EOF)
+          {
+            "environments": {
+              "test": {
+                "addons":[
+                  "heroku-postgresql:in-dyno"
+                ]
+              }
+            }
+          }
+        EOF
+      end
+
+      app.run_ci do |test_run|
+        expect(test_run.output).to match("db:schema:load completed")
+      end
+    end
+  end
+
+  it "Works with Rails: SQL schema apps" do
+    Hatchet::Runner.new("rails_8_sql_schema", stack: "heroku-24").tap do |app|
+      app.before_deploy do
+        Pathname("app.json").write(<<~EOF)
+          {
+            "environments": {
+              "test": {
+                "addons":[
+                  "heroku-postgresql:in-dyno"
+                ]
+              }
+            }
+          }
+        EOF
+      end
+
+      app.run_ci do |test_run|
+        expect(test_run.output).to match("db:schema:load completed")
+      end
+    end
+  end
+
+  it "Works with a vanilla ruby app" do
+    Hatchet::Runner.new("ruby_no_rails_test").run_ci do |test_run|
+      # Test no whitespace in front of output
+      expect(test_run.output).to_not match(/^ +Finished in/)
+      expect(test_run.output).to match(/^Finished in/)
+    end
+  end
+
+  it "Uses the cache" do
+    runner = Hatchet::Runner.new("ruby_no_rails_test")
+    runner.run_ci do |test_run|
+      fetching_rake = "Fetching rake"
+      expect(test_run.output).to match(fetching_rake)
+
+      test_run.run_again
+
+      expect(test_run.output).to_not match(fetching_rake)
+    end
+  end
+
+  it "Purges cache when stack changes" do
+    Hatchet::Runner.new("ruby_no_rails_test", stack: "heroku-24").tap do |app|
+      app.before_deploy do
+        Pathname("app.json").write(<<~EOF)
+          { "stack": "heroku-24" }
+        EOF
+      end
+
+      app.run_ci do |test_run|
+        expect(test_run.output).to include("Fetching rake")
+        expect(test_run.output).to_not include("Purging Cache")
+
+        # Change stack from heroku-24 to heroku-22
+        Pathname("app.json").write(<<~EOF)
+          { "stack": "heroku-22" }
+        EOF
+        run!("git add app.json && git commit -m 'Change stack to heroku-22'")
+
+        test_run.run_again
+
+        expect(test_run.output).to include("Purging Cache. Changing stack from heroku-24 to heroku-22")
+      end
+    end
+  end
+
+  it "CI build time config var behavior" do
+    script = "echo '## PRINTING ENV ##' && env | sort && echo '## PRINTING ENV DONE ##'; echo '## PRINTING BIN ## ' && ls -1 ./bin | sort && echo '## PRINTING BIN DONE ##'"
+
+    # First, capture env BEFORE the Ruby buildpack runs using an inline buildpack
+    before_output = nil
+    Hatchet::Runner.new("default_ruby", stack: DEFAULT_STACK, buildpacks: ["https://github.com/heroku/heroku-buildpack-inline.git"]).tap do |app|
+      app.before_deploy do
+        bin = Pathname("bin").tap(&:mkpath)
+        %w[detect compile release].each do |name|
+          path = bin.join(name)
+          FileUtils.touch(path)
+          FileUtils.chmod("+x", path)
+          path.write("#!/usr/bin/env bash\nexit 0\n")
+        end
+
+        Pathname("app.json").write(<<~EOF)
+          {
+            "environments": {
+              "test": {
+                "scripts": {
+                  "test": "#{script}"
+                }
+              }
+            }
+          }
+        EOF
+      end
+
+      app.run_ci do |test_run|
+        before_output = test_run.output
+      end
+    end
+
+    # Test `bin/test` auto executing code, which is a slightly different path than if they define a test task in the `app.json`
+    Hatchet::Runner.new("default_ruby", stack: DEFAULT_STACK).tap do |app|
+      app.before_deploy do
+        bin_rake = Pathname("bin").tap(&:mkpath).join("rake")
+        bin_rake.write(<<~EOF)
+          #!/usr/bin/env bash
+
+          # Only print markers when running the test task, not for other rake invocations
+          # like `rake -v` which the buildpack uses to detect rake tasks
+          if [[ "$1" == "test" ]]; then
+            #{script}
+          else
+            # Remove this script's directory from PATH to find the real rake
+            SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+            PATH="${PATH//$SCRIPT_DIR:/}" exec rake "$@"
+          fi
+        EOF
+        FileUtils.chmod("+x", bin_rake)
+
+        Pathname("Rakefile").write("") # triggers `rake test`
+      end
+
+      app.run_ci do |test_run|
+        combined_output = before_output + "\n" + test_run.output
+        diff = EnvDiff.new(combined_output, build_dir_pattern: nil)
+
+        expect(diff.added.join("\n")).to eq(<<~EOF.strip)
+          BUNDLE_BIN=vendor/bundle/bin
+          BUNDLE_DEPLOYMENT=1
+          BUNDLE_PATH=vendor/bundle
+          BUNDLE_WITHOUT=development
+          DISABLE_SPRING=1
+          GEM_PATH=/app/vendor/bundle/ruby/3.3.0:
+          LANG=en_US.UTF-8
+          MALLOC_ARENA_MAX=2
+          PUMA_PERSISTENT_TIMEOUT=95
+          RACK_ENV=test
+        EOF
+
+        expect(diff.path_after).to include(diff.path_before)
+        expect(diff.path_after).to start_with(
+          [
+            "/app/bin",
+            "/app/vendor/bundle/bin",
+            "/app/vendor/bundle/ruby/3.3.0/bin"
+          ].join(":")
+        )
+
+        expect(extract_remote_lines(test_run.output, start_marker: "## PRINTING BIN ##", end_marker: "## PRINTING BIN DONE ##"))
+          .to eq([
+            "rake", # `bin/rake` is explicitly added in this test
+            "erb", "gem", "irb", "racc", "rbs", "rdbg", "rdoc", "ri", "ruby", "ruby.exe", "syntax_suggest", "typeprof"
+          ].sort)
+      end
+    end
+  end
+
+  it "works" do
+    Hatchet::Runner.new("default_ruby", stack: DEFAULT_STACK).tap do |app|
+      app.before_deploy do
+        Pathname("Gemfile").write(<<~EOF)
+          source 'http://rubygems.org'
+          ruby '3.1.3'
+          gem 'sinatra'
+          gem 'puma'
+          gem 'rack'
+          gem 'rake'
+          gem 'rackup'
+
+          group :test do
+            gem 'rack-test'
+            gem 'test-unit'
+          end
+        EOF
+
+        Pathname("Gemfile.lock").write(<<~EOF)
+          GEM
+            remote: http://rubygems.org/
+            specs:
+              base64 (0.3.0)
+              logger (1.7.0)
+              mustermann (3.0.4)
+                ruby2_keywords (~> 0.0.1)
+              nio4r (2.7.4)
+              power_assert (3.0.1)
+              puma (7.1.0)
+                nio4r (~> 2.0)
+              rack (3.2.4)
+              rack-protection (4.2.1)
+                base64 (>= 0.1.0)
+                logger (>= 1.6.0)
+                rack (>= 3.0.0, < 4)
+              rack-session (2.1.1)
+                base64 (>= 0.1.0)
+                rack (>= 3.0.0)
+              rack-test (2.2.0)
+                rack (>= 1.3)
+              rackup (2.3.1)
+                rack (>= 3)
+              rake (13.3.1)
+              ruby2_keywords (0.0.5)
+              sinatra (4.2.1)
+                logger (>= 1.6.0)
+                mustermann (~> 3.0)
+                rack (>= 3.0.0, < 4)
+                rack-protection (= 4.2.1)
+                rack-session (>= 2.0.0, < 3)
+                tilt (~> 2.0)
+              test-unit (3.7.3)
+                power_assert
+              tilt (2.6.1)
+
+          PLATFORMS
+            ruby
+
+          DEPENDENCIES
+            puma
+            rack
+            rack-test
+            rackup
+            rake
+            sinatra
+            test-unit
+
+          RUBY VERSION
+             ruby 3.1.3p185
+
+          BUNDLED WITH
+             2.3.26
+
+        EOF
+
+        Pathname("Rakefile").write(<<~EOF)
+          require 'bundler/setup'
+          require 'rake/testtask'
+
+          Rake::TestTask.new
+        EOF
+      end
+
+      app.run_ci do |test_run|
+        expect(test_run.output).to match("Fetching rake")
+      end
+    end
+  end
+end
diff --git a/spec/hatchet/getting_started_spec.rb b/spec/hatchet/getting_started_spec.rb
new file mode 100644
index 000000000..56d802de0
--- /dev/null
+++ b/spec/hatchet/getting_started_spec.rb
@@ -0,0 +1,72 @@
+require_relative "../spec_helper"
+
+describe "Heroku ruby getting started" do
+  it "works on Heroku-24" do
+    Hatchet::Runner.new("ruby-getting-started", stack: "heroku-24").deploy do |app|
+      expect(app.output).to_not include("Purging Cache")
+      expect(app.output).to include("Fetching puma")
+
+      secret_key_base = app.run("echo $SECRET_KEY_BASE")
+
+      set_bundler_version(version: "2.6.9")
+
+      # Re-deploy with cache
+      run!("git add .; git commit -m 'Change bundler version'")
+      app.push!
+
+      # Assert used cached gems
+      expect(app.output).to_not include("Fetching puma")
+      expect(app.output).to include("Gems included by the bundle") # bundle list output
+
+      # Assert no warnings from `cp`
+      # https://github.com/heroku/heroku-buildpack-ruby/pull/1586/files#r2064284286
+      expect(app.output).to_not include("cp --help")
+      expect(app.run("command -v ruby").strip).to eq("/app/bin/ruby")
+
+      environment_variables = app.run("env")
+      expect(environment_variables).to match("PUMA_PERSISTENT_TIMEOUT")
+      # Assert cached value persisted
+      expect(environment_variables).to match("SECRET_KEY_BASE=#{secret_key_base}")
+
+      profile_d = app.run("cat .profile.d/ruby.sh")
+        .strip
+        .split("\n")
+        .sort
+        .join("\n")
+
+      # SECRET_KEY_BASE has a non-deterministic value, assert it exists but remove from equality check
+      expect(profile_d).to match("SECRET_KEY_BASE")
+      profile_d.gsub!(/$\s*export SECRET_KEY_BASE=.*/, "")
+
+      expect(profile_d).to eq(<<~EOF.strip)
+        export BUNDLE_BIN=${BUNDLE_BIN:-vendor/bundle/bin}
+        export BUNDLE_DEPLOYMENT=${BUNDLE_DEPLOYMENT:-1}
+        export BUNDLE_PATH=${BUNDLE_PATH:-vendor/bundle}
+        export BUNDLE_WITHOUT=${BUNDLE_WITHOUT:-development:test}
+        export DISABLE_SPRING="1"
+        export GEM_PATH="$HOME/vendor/bundle/ruby/3.4.0:$GEM_PATH"
+        export LANG=${LANG:-en_US.UTF-8}
+        export MALLOC_ARENA_MAX=${MALLOC_ARENA_MAX:-2}
+        export PATH="$HOME/bin:$HOME/vendor/bundle/bin:$HOME/vendor/bundle/ruby/3.4.0/bin:$PATH"
+        export PUMA_PERSISTENT_TIMEOUT=${PUMA_PERSISTENT_TIMEOUT:-95}
+        export RACK_ENV=${RACK_ENV:-production}
+        export RAILS_ENV=${RAILS_ENV:-production}
+        export RAILS_LOG_TO_STDOUT=${RAILS_LOG_TO_STDOUT:-enabled}
+        export RAILS_SERVE_STATIC_FILES=${RAILS_SERVE_STATIC_FILES:-enabled}
+      EOF
+    end
+  end
+
+  it "works on Heroku-22" do
+    Hatchet::Runner.new("ruby-getting-started", stack: "heroku-22").deploy do |app|
+      # Re-deploy with cache
+      run!("git commit --allow-empty -m empty")
+      app.push!
+
+      # Assert no warnings from `cp`
+      # https://github.com/heroku/heroku-buildpack-ruby/pull/1586/files#r2064284286
+      expect(app.output).to_not include("cp --help")
+      expect(app.run("command -v ruby").strip).to eq("/app/bin/ruby")
+    end
+  end
+end
diff --git a/spec/hatchet/node_spec.rb b/spec/hatchet/node_spec.rb
new file mode 100644
index 000000000..52caae77d
--- /dev/null
+++ b/spec/hatchet/node_spec.rb
@@ -0,0 +1,44 @@
+require "spec_helper"
+
+describe "Node and Yarn" do
+  it "works without the node buildpack" do
+    buildpacks = [
+      :default,
+      "https://github.com/sharpstone/force_absolute_paths_buildpack"
+    ]
+    config = {FORCE_ABSOLUTE_PATHS_BUILDPACK_IGNORE_PATHS: "BUNDLE_PATH"}
+
+    Hatchet::Runner.new("minimal_webpacker", buildpacks: buildpacks, config: config).deploy do |app, heroku|
+      # https://rubular.com/r/4bkL8fYFTQwt0Q
+      expect(app.output).to match(/vendor\/yarn-v\d+\.\d+\.\d+\/bin\/yarn is the yarn directory/)
+      expect(app.output).to_not include(".heroku/yarn/bin/yarn is the yarn directory")
+
+      expect(app.output).to include("bin/node is the node directory")
+      expect(app.output).to_not include(".heroku/node/bin/node is the node directory")
+
+      expect(app.output).to include("Installing a default version (#{LanguagePack::Helpers::Nodebin::YARN_VERSION}) of Yarn")
+      expect(app.output).to include("Installing a default version (#{LanguagePack::Helpers::Nodebin::NODE_VERSION}) of Node.js")
+
+      expect(app.run("command -v node")).to match("/app/bin/node")     # We put node in bin/node
+      expect(app.run("command -v yarn")).to match("/app/vendor/yarn-") # We put yarn in /app/vendor/yarn-
+    end
+  end
+
+  it "works with the node buildpack" do
+    buildpacks = [
+      "heroku/nodejs",
+      :default,
+      "https://github.com/sharpstone/force_absolute_paths_buildpack"
+    ]
+    config = {FORCE_ABSOLUTE_PATHS_BUILDPACK_IGNORE_PATHS: "BUNDLE_PATH"}
+
+    Hatchet::Runner.new("minimal_webpacker", buildpacks: buildpacks, config: config).deploy do |app, heroku|
+      expect(app.output).to include("yarn install")
+      expect(app.output).to include(".heroku/node/bin/yarn is the yarn directory ")
+      expect(app.output).to include(".heroku/node/bin/node is the node directory")
+
+      expect(app.run("command -v node")).to match("/app/.heroku/node/bin")
+      expect(app.run("command -v yarn")).to match("/app/.heroku/node/bin")
+    end
+  end
+end
diff --git a/spec/hatchet/rails23_spec.rb b/spec/hatchet/rails23_spec.rb
new file mode 100644
index 000000000..9d42926a4
--- /dev/null
+++ b/spec/hatchet/rails23_spec.rb
@@ -0,0 +1,13 @@
+require_relative "../spec_helper"
+
+describe "Rails 2.3.x" do
+  it "should deploy" do
+    skip("Need RAILS_LTS_CREDS env var set") unless ENV["RAILS_LTS_CREDS"]
+
+    Hatchet::Runner.new("rails_lts_23_default_ruby", config: rails_lts_config, stack: rails_lts_stack).tap do |app|
+      app.deploy do
+        # assert deploy is successful
+      end
+    end
+  end
+end
diff --git a/spec/hatchet/rails3_spec.rb b/spec/hatchet/rails3_spec.rb
new file mode 100644
index 000000000..210607ccf
--- /dev/null
+++ b/spec/hatchet/rails3_spec.rb
@@ -0,0 +1,29 @@
+require_relative "../spec_helper"
+
+describe "Rails 3.x" do
+  it "should deploy and inject plugins" do
+    skip("Need RAILS_LTS_CREDS env var set") unless ENV["RAILS_LTS_CREDS"]
+
+    Hatchet::Runner.new("rails3_default_ruby", config: rails_lts_config, stack: rails_lts_stack).tap do |app|
+      app.before_deploy do
+        set_lts_ruby_version
+        set_bundler_version(version: :default)
+      end
+
+      app.deploy do
+        # Rails 3 doesn't work with Postgres 8+ out of the box and Rails
+        # LTS hasn't patched this yet. We're skipping asset compilation for now
+        # by deleting the Rakefile
+        #
+        # expect(app.output).to include("Asset precompilation completed")
+
+        expect(app.output).to match("WARNING")
+        expect(app.output).to match("Add 'rails_12factor' gem to your Gemfile to skip plugin injection")
+
+        ls = app.run("ls vendor/plugins")
+        expect(ls).to match("rails3_serve_static_assets")
+        expect(ls).to match("rails_log_stdout")
+      end
+    end
+  end
+end
diff --git a/spec/hatchet/rails4_spec.rb b/spec/hatchet/rails4_spec.rb
new file mode 100644
index 000000000..cdd1b5234
--- /dev/null
+++ b/spec/hatchet/rails4_spec.rb
@@ -0,0 +1,60 @@
+require_relative "../spec_helper"
+
+describe "Rails 4.x" do
+  it "should be able to run a migration without heroku specific database.yml" do
+    skip("Need RAILS_LTS_CREDS env var set") unless ENV["RAILS_LTS_CREDS"]
+
+    Hatchet::Runner.new("rails42_default_ruby", config: rails_lts_config, stack: rails_lts_stack).tap do |app|
+      app.before_deploy do
+        set_lts_ruby_version
+        set_bundler_version(version: :default)
+      end
+      app.deploy do
+        # it Don't over-write database.yml
+        expect(app.output).not_to include("Writing config/database.yml to read from DATABASE_URL")
+
+        # it sets RAILS_SERVE_STATIC_FILES env var
+        output = app.run("rails runner 'puts ENV[%Q{RAILS_SERVE_STATIC_FILES}].present?'")
+        expect(output).to match(/true/)
+      end
+    end
+  end
+
+  it "should skip asset compilation when deployed with NEW manifest file" do
+    skip("Need RAILS_LTS_CREDS env var set") unless ENV["RAILS_LTS_CREDS"]
+
+    Hatchet::Runner.new("rails42_default_ruby", config: rails_lts_config, stack: rails_lts_stack).tap do |app|
+      app.before_deploy do
+        set_lts_ruby_version
+        set_bundler_version(version: :default)
+        Pathname("public/assets/manifest-ccf61eade4793995271564a4767ce6b6.json").tap { |p|
+          p.dirname.mkpath
+          FileUtils.touch(p)
+        }
+      end
+
+      app.deploy do
+        expect(app.output).to include("Detected manifest file, assuming assets were compiled locally")
+      end
+    end
+  end
+
+  it "should skip asset compilation when deployed with OLD manifest file" do
+    skip("Need RAILS_LTS_CREDS env var set") unless ENV["RAILS_LTS_CREDS"]
+
+    Hatchet::Runner.new("rails42_default_ruby", config: rails_lts_config, stack: rails_lts_stack).tap do |app|
+      app.before_deploy do
+        set_lts_ruby_version
+        set_bundler_version(version: :default)
+        Pathname("public/assets/.sprockets-manifest-040763ccc5036260c52c6adcf77d73f7.json").tap { |p|
+          p.dirname.mkpath
+          FileUtils.touch(p)
+        }
+      end
+
+      app.deploy do
+        expect(app.output).to include("Detected manifest file, assuming assets were compiled locally")
+      end
+    end
+  end
+end
diff --git a/spec/hatchet/rails6_spec.rb b/spec/hatchet/rails6_spec.rb
new file mode 100644
index 000000000..e28470e2b
--- /dev/null
+++ b/spec/hatchet/rails6_spec.rb
@@ -0,0 +1,33 @@
+require_relative "../spec_helper"
+
+describe "Rails 6" do
+  it "should detect successfully" do
+    Hatchet::App.new("rails61").in_directory_fork do
+      bundler = LanguagePack::Helpers::BundlerWrapper.new(
+        bundler_path: Dir.mktmpdir,
+        bundler_version: LanguagePack::Helpers::BundlerWrapper::DEFAULT_VERSION
+      )
+      expect(LanguagePack::Rails5.use?(bundler: bundler)).to eq(false)
+      expect(LanguagePack::Rails6.use?(bundler: bundler)).to eq(true)
+    end
+  end
+
+  it "deploys and serves web requests via puma" do
+    before_deploy = proc do
+      run! "echo 'web: bundle exec puma -t 5:5 -p ${PORT:-3000} -e ${RACK_ENV:-development}' > Procfile"
+
+      # Test Clean task does not get called if it does not exist
+      # This file will only have the `assets:precompile` task in it, but not `assets:clean`
+      run! %(echo 'task "assets:precompile" do ; end' > Rakefile)
+    end
+
+    Hatchet::Runner.new("rails61", before_deploy: before_deploy, config: rails_lts_config, stack: rails_lts_stack).deploy do |app|
+      expect(app.output).to match("Fetching railties 6")
+
+      expect(app.output).to match("rake assets:precompile")
+      expect(app.output).to_not match("rake assets:clean")
+
+      expect(web_boot_status(app)).to_not eq("crashed")
+    end
+  end
+end
diff --git a/spec/hatchet/rails7_spec.rb b/spec/hatchet/rails7_spec.rb
new file mode 100644
index 000000000..853fd1142
--- /dev/null
+++ b/spec/hatchet/rails7_spec.rb
@@ -0,0 +1,30 @@
+require_relative "../spec_helper"
+
+describe "Rails 7" do
+  it "should detect successfully" do
+    Hatchet::App.new("rails-jsbundling").in_directory_fork do
+      bundler = LanguagePack::Helpers::BundlerWrapper.new(
+        bundler_path: Dir.mktmpdir,
+        bundler_version: LanguagePack::Helpers::BundlerWrapper::DEFAULT_VERSION
+      )
+      expect(LanguagePack::Rails6.use?(bundler: bundler)).to eq(false)
+      expect(LanguagePack::Rails7.use?(bundler: bundler)).to eq(true)
+    end
+  end
+
+  it "works with jsbundling" do
+    Hatchet::Runner.new("rails-jsbundling").tap do |app|
+      app.deploy do
+        expect(app.output).to include("yarn install")
+        expect(app.output).to include("Asset precompilation completed")
+      end
+    end
+  end
+
+  it "Works on Heroku CI" do
+    Hatchet::Runner.new("rails-jsbundling").run_ci do |test_run|
+      expect(test_run.output).to match("db:schema:load")
+      expect(test_run.output).to match("db:migrate")
+    end
+  end
+end
diff --git a/spec/hatchet/rails8_spec.rb b/spec/hatchet/rails8_spec.rb
new file mode 100644
index 000000000..4edc92ff4
--- /dev/null
+++ b/spec/hatchet/rails8_spec.rb
@@ -0,0 +1,4 @@
+require_relative "../spec_helper"
+
+describe "Rails 8" do
+end
diff --git a/spec/hatchet/rubies_spec.rb b/spec/hatchet/rubies_spec.rb
new file mode 100644
index 000000000..1407532e2
--- /dev/null
+++ b/spec/hatchet/rubies_spec.rb
@@ -0,0 +1,85 @@
+require_relative "../spec_helper"
+
+describe "Ruby versions" do
+  it "should deploy jdk on heroku-24" do
+    Hatchet::Runner.new("default_ruby", stack: "heroku-24").tap do |app|
+      app.before_deploy do |app|
+        Pathname("Gemfile.lock").write(<<~EOM)
+          GEM
+            remote: https://rubygems.org/
+            specs:
+              rack (3.1.8)
+              rake (13.2.1)
+              webrick (1.9.1)
+
+          PLATFORMS
+            java
+
+          DEPENDENCIES
+            rack
+            rake
+            webrick
+
+          RUBY VERSION
+             ruby 3.1.4p0 (jruby 9.4.8.0)
+
+          BUNDLED WITH
+             2.5.23
+        EOM
+
+        Pathname("Rakefile").write(<<~'EOM')
+          task "assets:precompile" do
+            puts "JRUBY_OPTS is: #{ENV['JRUBY_OPTS']}"
+          end
+        EOM
+      end
+
+      app.deploy do
+        expect(app.output).to match("JRUBY_OPTS is: -Xcompile.invokedynamic=false")
+
+        app.set_config("JRUBY_BUILD_OPTS" => "--dev")
+        app.commit!
+        app.push!
+        expect(app.output).to match("JRUBY_OPTS is: --dev")
+
+        expect(app.run("ruby -v")).to match("jruby")
+      end
+    end
+  end
+end
+
+describe "Ruby on heroku-26" do
+  it "deploys Ruby 3.3.10" do
+    Hatchet::Runner.new("default_ruby", stack: "heroku-26").tap do |app|
+      app.before_deploy do
+        set_ruby_version(version: "3.3.10")
+      end
+
+      app.deploy do |app|
+        expect(app.run("command -v ruby").strip).to eq("/app/bin/ruby")
+      end
+    end
+  end
+end
+
+describe "Upgrading ruby apps" do
+  it "works when changing versions" do
+    version = "3.3.1"
+    expect(version).to_not eq(LanguagePack::RubyVersion::DEFAULT_VERSION_NUMBER)
+    app = Hatchet::Runner.new("default_ruby", stack: DEFAULT_STACK)
+    app.deploy do |app|
+      # default version
+      expect(app.run("env | grep MALLOC_ARENA_MAX")).to match("MALLOC_ARENA_MAX=2")
+      expect(app.run("env | grep DISABLE_SPRING")).to match("DISABLE_SPRING=1")
+
+      # Deploy again
+      set_ruby_version(version: version)
+
+      run!("git add -A; git commit -m update-ruby")
+      app.push!
+      expect(app.output).to match(version)
+      expect(app.run("ruby -v")).to match(version)
+      expect(app.output).to match("Ruby version change detected")
+    end
+  end
+end
diff --git a/spec/hatchet/ruby_spec.rb b/spec/hatchet/ruby_spec.rb
new file mode 100644
index 000000000..7182ef3c5
--- /dev/null
+++ b/spec/hatchet/ruby_spec.rb
@@ -0,0 +1,399 @@
+require_relative "../spec_helper"
+
+describe "Ruby apps" do
+  # https://github.com/heroku/heroku-buildpack-ruby/issues/1025
+  describe "bin/rake binstub" do
+    it "loads git gems at build time when executing `rake`" do
+      Hatchet::Runner.new("git_gemspec").tap do |app|
+        app.before_deploy do
+          File.open("Rakefile", "w+") do |f|
+            f.puts(<<~EOF)
+              task "assets:precompile" do
+                require 'mini_histogram'
+                puts "successfully loaded git gem"
+              end
+            EOF
+          end
+        end
+        app.deploy do
+          expect(app.output).to match("successfully loaded git gem")
+          expect(app.run("rake assets:precompile")).to match("successfully loaded git gem")
+        end
+      end
+    end
+
+    it "loads bundler into memory" do
+      Hatchet::Runner.new("default_ruby").tap do |app|
+        app.before_deploy do
+          File.open("Rakefile", "w+") do |f|
+            f.puts(<<~EOF)
+              task "assets:precompile" do
+                puts Bundler.methods
+
+                puts "bundler loaded in rake context"
+              end
+            EOF
+          end
+        end
+        app.deploy do
+          expect(app.output).to match("bundler loaded in rake context")
+          expect(app.run("rake assets:precompile")).to match("bundler loaded in rake context")
+        end
+      end
+    end
+
+    it "loads custom rake binstub" do
+      Hatchet::Runner.new("default_ruby").tap do |app|
+        app.before_deploy do
+          FileUtils.mkdir_p("bin")
+
+          File.open("bin/rake", "w+") do |f|
+            f.puts(<<~EOF)
+              #!/usr/bin/env ruby
+
+              puts "rake assets:precompile" # Needed to trigger the `rake -P` task detection
+              puts "custom rake binstub called"
+            EOF
+          end
+          FileUtils.chmod("+x", "bin/rake")
+        end
+        app.deploy do
+          expect(app.output).to match("custom rake binstub called")
+          # Using `bash -c rake` here to bypass heroku process type detection because
+          # rake = "bundle exec rake" is a process type. This test was previously
+          # relying on a bug in the CLI that was fixed in https://github.com/heroku/cli/pull/3804.
+          # The goal is to test PATH resolution at build/runtime.
+          expect(app.run("bash -c rake")).to match("custom rake binstub called")
+        end
+      end
+    end
+  end
+
+  describe "bad ruby version" do
+    it "gives a helpful error" do
+      Hatchet::Runner.new("default_ruby", allow_failure: true, stack: DEFAULT_STACK).tap do |app|
+        app.before_deploy do
+          set_ruby_version(version: "2.9.0.lol")
+        end
+
+        app.deploy do |app|
+          expect(app.output).to match("The Ruby version you are trying to install does not exist: ruby-2.9.0.lol")
+        end
+      end
+    end
+  end
+
+  describe "exporting path" do
+    it "puts local bin dir in path" do
+      before_deploy = proc do
+        FileUtils.mkdir_p("bin")
+        File.open("bin/bloop", "w+") do |f|
+          f.puts(<<~EOF)
+            #!/usr/bin/env bash
+
+            echo "bloop"
+          EOF
+        end
+        FileUtils.chmod("+x", "bin/bloop")
+
+        File.open("Rakefile", "a") do |f|
+          f.puts(<<~EOF)
+            task "run:bloop" do
+              puts `bloop`
+              raise "Could not bloop" unless $?.success?
+            end
+          EOF
+        end
+      end
+      buildpacks = [
+        :default,
+        "https://github.com/schneems/buildpack-ruby-rake-deploy-tasks"
+      ]
+      config = {"DEPLOY_TASKS" => "run:bloop"}
+      Hatchet::Runner.new("default_ruby", stack: DEFAULT_STACK, buildpacks: buildpacks, config: config, before_deploy: before_deploy).deploy do |app|
+        expect(app.output).to match("bloop")
+      end
+    end
+  end
+
+  describe "running Ruby from outside the default dir" do
+    it "works" do
+      buildpacks = [
+        :default,
+        "https://github.com/sharpstone/force_absolute_paths_buildpack",
+        "https://github.com/heroku/heroku-buildpack-inline.git"
+      ]
+      config = {FORCE_ABSOLUTE_PATHS_BUILDPACK_IGNORE_PATHS: "BUNDLE_PATH"}
+
+      Hatchet::Runner.new("default_ruby", stack: DEFAULT_STACK, buildpacks: buildpacks, config: config).tap do |app|
+        app.before_deploy do
+          Pathname("Gemfile").write(<<~EOF)
+            source "https://rubygems.org"
+
+            gem "rake"
+          EOF
+
+          Pathname("Gemfile.lock").write(<<~EOF)
+            GEM
+              remote: https://rubygems.org/
+              specs:
+                rake (13.0.6)
+
+            PLATFORMS
+              ruby
+              x86_64-darwin-20
+
+            DEPENDENCIES
+              rake
+
+            RUBY VERSION
+               ruby 3.3.1p0
+          EOF
+
+          Pathname("Rakefile").write(<<~'EOF')
+            task "assets:precompile" do
+              out = `cd client && bundle exec ruby -v`
+              puts "cd version #{out}"
+              unless $?.success?
+                puts "Failed: #{out}"
+                exit 1
+              end
+            end
+          EOF
+
+          Pathname(".ruby-version").write("3.3.1")
+
+          dir = Pathname("client")
+          dir.mkpath
+          FileUtils.touch(dir.join(".gitkeep"))
+
+          # Inline buildpack to ensure build_report file is emitted on compile
+          bin = Pathname("bin").tap(&:mkpath)
+          detect = bin.join("detect")
+          compile = bin.join("compile")
+          release = bin.join("release")
+
+          [detect, compile, release].each do |path|
+            FileUtils.touch(path)
+            FileUtils.chmod("+x", path)
+            path.write(<<~EOF)
+              #!/usr/bin/env bash
+              exit 0
+            EOF
+          end
+
+          bash_functions_contents = Pathname(__dir__).join("..").join("..").join("bin").join("support").join("bash_functions.sh").read
+          bin.join("support").tap(&:mkpath).join("bash_functions.sh").write(<<~EOF)
+            #{bash_functions_contents}
+          EOF
+
+          compile.write(<<~EOF)
+            #!/usr/bin/env bash
+
+            echo "## PRINTING REPORT FILE ##"
+            #{Pathname(__dir__).join("..").join("..").join("bin").join("report").read}
+            echo "## REPORT FILE DONE ##"
+          EOF
+        end
+
+        app.deploy do |app|
+          expected = "3.3.1"
+          expect(expected).to_not eq(LanguagePack::RubyVersion::DEFAULT_VERSION_NUMBER)
+          expect(app.output).to match("cd version ruby #{expected}")
+          begin
+            report_match = app.output.match(/## PRINTING REPORT FILE ##(?<yaml>.*)## REPORT FILE DONE/m) # https://rubular.com/r/FfaV5AEstigaMO
+            expect(report_match).to be_truthy
+            yaml = report_match[:yaml].gsub("remote: ", "")
+            report = YAML.load(yaml)
+            expect(report.fetch("ruby_version_full")).to eq(expected)
+            expect(report.fetch("dot_ruby_version.version")).to eq(expected)
+            expect(report.fetch("dot_ruby_version.vs_gemfile_lock")).to eq("match")
+          rescue Exception => e # standard:disable Lint/RescueException
+            puts app.output
+            puts yaml if yaml
+            puts report.inspect if report
+            raise e
+          end
+
+          expect(app.run("command -v ruby").strip).to eq("/app/bin/ruby")
+        end
+      end
+    end
+  end
+
+  describe "database configuration" do
+    context "no active record" do
+      it "writes a heroku specific database.yml" do
+        Hatchet::Runner.new("default_ruby").deploy do |app, heroku|
+          expect(app.output).to include("Writing config/database.yml to read from DATABASE_URL")
+          expect(app.output).not_to include("Your app was upgraded to bundler")
+          expect(app.output).not_to include("Your Ruby version is not present on the next stack")
+        end
+      end
+    end
+
+    context "active record 4.1+" do
+      it "doesn't write a heroku specific database.yml" do
+        Hatchet::Runner.new("rails61", config: rails_lts_config, stack: rails_lts_stack).tap do |app|
+          app.deploy do
+            expect(app.output).not_to include("Writing config/database.yml to read from DATABASE_URL")
+          end
+        end
+      end
+    end
+  end
+end
+
+describe "Raise errors on specific gems" do
+  it "should raise on sqlite3" do
+    Hatchet::Runner.new("sqlite3_gemfile", allow_failure: true).deploy do |app|
+      expect(app).not_to be_deployed
+      expect(app.output).to include("Detected sqlite3 gem which is not supported")
+      expect(app.output).to include("devcenter.heroku.com/articles/sqlite3")
+    end
+  end
+end
+
+describe "No Lockfile" do
+  it "should not deploy" do
+    Hatchet::Runner.new("no_lockfile", allow_failure: true).deploy do |app|
+      expect(app).not_to be_deployed
+      expect(app.output).to include("Gemfile.lock required")
+    end
+  end
+end
+
+describe "Rack" do
+  it "should not overwrite already set environment variables" do
+    custom_env = SecureRandom.hex(16)
+    app = Hatchet::Runner.new("default_ruby", config: {"RACK_ENV" => custom_env, "BUNDLE_SIMULATE_VERSION" => "4"})
+    app.before_deploy do
+      Pathname("Rakefile").write(<<~'EOF')
+        task "assets:precompile" do
+          puts "Build time RACK_ENV: #{ENV["RACK_ENV"]}"
+        end
+      EOF
+
+      set_bundler_version(version: "2.7.2")
+    end
+
+    app.deploy do |app|
+      # Assert build time user provided value takes precedence over default
+      expect(app.output).to match("Build time RACK_ENV: #{custom_env}")
+
+      # Assert runtime/launch user provided value takes precedence over default
+      environment_variables = app.run("env")
+      expect(environment_variables).to match("RACK_ENV=#{custom_env}")
+      expect(environment_variables).to match("PUMA_PERSISTENT_TIMEOUT")
+
+      profile_d = app.run("cat .profile.d/ruby.sh")
+        .strip
+        .split("\n")
+        .sort
+        .join("\n")
+
+      expect(profile_d).to eq(<<~EOF.strip)
+        export BUNDLE_BIN=${BUNDLE_BIN:-vendor/bundle/bin}
+        export BUNDLE_DEPLOYMENT=${BUNDLE_DEPLOYMENT:-1}
+        export BUNDLE_PATH=${BUNDLE_PATH:-vendor/bundle}
+        export BUNDLE_WITHOUT=${BUNDLE_WITHOUT:-development:test}
+        export DISABLE_SPRING="1"
+        export GEM_PATH="$HOME/vendor/bundle/ruby/3.3.0:$GEM_PATH"
+        export LANG=${LANG:-en_US.UTF-8}
+        export MALLOC_ARENA_MAX=${MALLOC_ARENA_MAX:-2}
+        export PATH="$HOME/bin:$HOME/vendor/bundle/bin:$HOME/vendor/bundle/ruby/3.3.0/bin:$PATH"
+        export PUMA_PERSISTENT_TIMEOUT=${PUMA_PERSISTENT_TIMEOUT:-95}
+        export RACK_ENV=${RACK_ENV:-production}
+      EOF
+    end
+  end
+end
+
+describe "build time config var behavior" do
+  it "works" do
+    # Print out the `env` of the build process before and after the Ruby buildpack and diff the results
+    buildpacks = [
+      "https://github.com/heroku/heroku-buildpack-inline.git",
+      :default,
+      "https://github.com/heroku/heroku-buildpack-inline.git"
+    ]
+
+    Hatchet::Runner.new("default_ruby", stack: DEFAULT_STACK, buildpacks: buildpacks).tap do |app|
+      app.before_deploy do
+        bin = Pathname("bin").tap(&:mkpath)
+        detect = bin.join("detect")
+        compile = bin.join("compile")
+        release = bin.join("release")
+
+        [detect, compile, release].each do |path|
+          FileUtils.touch(path)
+          FileUtils.chmod("+x", path)
+          path.write(<<~EOF)
+            #!/usr/bin/env bash
+            exit 0
+          EOF
+        end
+
+        compile.write(<<~EOF)
+          #!/usr/bin/env bash
+          set -euo pipefail
+
+          BUILD_DIR=$1
+          echo "BUILD_DIR: $BUILD_DIR"
+
+          echo "## PRINTING ENV ##"
+          env | sort
+          echo "## PRINTING ENV DONE ##"
+          exit 0
+        EOF
+      end
+
+      app.deploy do
+        diff = EnvDiff.new(app.output)
+
+        expect(diff.added.join("\n")).to eq(<<~EOF.strip)
+          BUNDLE_BIN=vendor/bundle/bin
+          BUNDLE_DEPLOYMENT=1
+          BUNDLE_PATH=vendor/bundle
+          BUNDLE_WITHOUT=development:test
+          GEM_PATH=<build dir>/vendor/bundle/ruby/3.3.0:
+          PUMA_PERSISTENT_TIMEOUT=95
+          RACK_ENV=production
+        EOF
+
+        expect(diff.path_after).to include(diff.path_before)
+        expect(diff.path_after).to include(
+          [
+            "<build dir>/bin",
+            "<build dir>/vendor/bundle/bin",
+            "<build dir>/vendor/bundle/ruby/3.3.0/bin",
+            "<build dir>/vendor/ruby-3.3.9/bin"
+          ].join(":")
+        )
+      end
+    end
+  end
+end
+
+describe "WEB_CONCURRENCY.sh" do
+  it "from a preceding buildpack is overwritten by this buildpack" do
+    buildpacks = [
+      "heroku/nodejs",
+      :default
+    ]
+    before_deploy = -> { run!(%(echo "{}" > package.json)) }
+    Hatchet::Runner.new("default_ruby", stack: DEFAULT_STACK, buildpacks: buildpacks, before_deploy: before_deploy).deploy do |app|
+      expect(app.run("cat .profile.d/WEB_CONCURRENCY.sh").strip).to be_empty
+      expect(app.run("echo $WEB_CONCURRENCY").strip).to be_empty
+      expect(app.run("echo $WEB_CONCURRENCY", heroku: {env: "WEB_CONCURRENCY=0"}).strip).to eq("0")
+    end
+  end
+
+  it "with SENSIBLE_DEFAULTS on sets environment variables" do
+    Hatchet::Runner.new("default_ruby", stack: DEFAULT_STACK, config: {"SENSIBLE_DEFAULTS" => "1"}).deploy do |app|
+      expect(app.run("cat .profile.d/WEB_CONCURRENCY.sh").strip).not_to be_empty
+      expect(app.run("echo $HEROKU_RAM_LIMIT_MB $WEB_CONCURRENCY $WEB_CONCURRENCY_SET_BY").strip).to eq("512 2 heroku/ruby")
+      expect(app.run("echo $WEB_CONCURRENCY", heroku: {env: "WEB_CONCURRENCY=3"}).strip).to eq("3")
+    end
+  end
+end
diff --git a/spec/helpers/binstub_check_spec.rb b/spec/helpers/binstub_check_spec.rb
new file mode 100644
index 000000000..477efd55f
--- /dev/null
+++ b/spec/helpers/binstub_check_spec.rb
@@ -0,0 +1,94 @@
+require_relative "../spec_helper"
+
+describe LanguagePack::Helpers::BinstubCheck do
+  def get_ruby_path!
+    out = `command -v ruby 2>/dev/null`.strip
+    raise "command `command -v ruby` failed with output: #{out}" unless $?.success?
+
+    Pathname.new(out)
+  end
+
+  def get_ruby_bin_dir!
+    ruby_bin_dir = get_ruby_path!.join("..")
+    raise "#{ruby_bin_dir} is not a directory" unless File.directory?(ruby_bin_dir)
+
+    ruby_bin_dir
+  end
+
+  it "handles empty binstubs" do
+    Tempfile.create("foo.txt") do |f|
+      expect { Pathname.new(f).open(&:readline) }.to raise_error(EOFError)
+
+      binstub = LanguagePack::Helpers::BinstubWrapper.new(f.path)
+      expect(binstub.bad_shebang?).to be_falsey
+      expect(binstub.binary?).to be_falsey
+    end
+  end
+
+  it "can determine if a file is binary or not" do
+    binstub = LanguagePack::Helpers::BinstubWrapper.new(get_ruby_path!)
+
+    expect(binstub.bad_shebang?).to be_falsey
+    expect(binstub.binary?).to be_truthy
+
+    Tempfile.create("foo.txt") do |f|
+      f.write("foo")
+      f.close
+      binstub = LanguagePack::Helpers::BinstubWrapper.new(f.path)
+
+      expect(binstub.bad_shebang?).to be_falsey
+      expect(binstub.binary?).to be_falsey
+    end
+  end
+
+  it "doesn't error on empty directories" do
+    Dir.mktmpdir do |dir|
+      warn_obj = Object.new
+      check = LanguagePack::Helpers::BinstubCheck.new(app_root_dir: dir, warn_object: warn_obj)
+      check.call
+    end
+  end
+
+  it "does not raise an error when running against a directory with a binary file in it" do
+    ruby_bin_dir = get_ruby_bin_dir!
+    check = LanguagePack::Helpers::BinstubCheck.new(app_root_dir: ruby_bin_dir, warn_object: Object.new)
+    check.call
+  end
+
+  it "checks binstubs and finds bad ones" do
+    Dir.mktmpdir do |dir|
+      bin_dir = Pathname.new(dir).join("bin")
+      bin_dir.mkpath
+
+      # Bad binstub
+      bin_dir.join("bad_binstub_example").write(<<~EOM)
+        #!/usr/bin/env ruby2.5
+
+        nothing else matters
+      EOM
+
+      # Good binstub
+      bin_dir.join("good_binstub_example").write(<<~EOM)
+        #!/usr/bin/env bash
+
+        nothing else matters
+      EOM
+      bin_dir.join("good_binstub_example_two").write("#!/usr/bin/env ruby")
+
+      warn_obj = Object.new
+      def warn_obj.warn(*args, **kwargs)
+        @msg = args.first
+      end
+
+      def warn_obj.msg
+        @msg
+      end
+
+      check = LanguagePack::Helpers::BinstubCheck.new(app_root_dir: dir, warn_object: warn_obj)
+      check.call
+
+      expect(check.bad_binstubs.count).to eq(1)
+      expect(warn_obj.msg).to include("bin/bad_binstub_example")
+    end
+  end
+end
diff --git a/spec/helpers/bundle_binstub_check_spec.rb b/spec/helpers/bundle_binstub_check_spec.rb
new file mode 100644
index 000000000..09d931706
--- /dev/null
+++ b/spec/helpers/bundle_binstub_check_spec.rb
@@ -0,0 +1,64 @@
+require_relative "../spec_helper"
+
+describe LanguagePack::Helpers::BundleBinstubCheck do
+  def make_warn_obj
+    warn_obj = Object.new
+    def warn_obj.warn(*args, **kwargs)
+      @msg = args.first
+    end
+
+    def warn_obj.msg
+      @msg
+    end
+
+    warn_obj
+  end
+
+  it "warns when bin/bundle exists" do
+    Dir.mktmpdir do |dir|
+      bin_dir = Pathname.new(dir).join("bin")
+      bin_dir.mkpath
+      bin_dir.join("bundle").write("#!/usr/bin/env ruby\n")
+
+      warn_obj = make_warn_obj
+      check = LanguagePack::Helpers::BundleBinstubCheck.new(
+        app_root_dir: dir,
+        warn_object: warn_obj
+      )
+      check.call
+
+      expect(warn_obj.msg).to include("bin/bundle")
+      expect(warn_obj.msg).to include("rm bin/bundle")
+    end
+  end
+
+  it "does not warn when bin/bundle does not exist" do
+    Dir.mktmpdir do |dir|
+      bin_dir = Pathname.new(dir).join("bin")
+      bin_dir.mkpath
+      bin_dir.join("rails").write("#!/usr/bin/env ruby\n")
+
+      warn_obj = make_warn_obj
+      check = LanguagePack::Helpers::BundleBinstubCheck.new(
+        app_root_dir: dir,
+        warn_object: warn_obj
+      )
+      check.call
+
+      expect(warn_obj.msg).to be_nil
+    end
+  end
+
+  it "does not warn when bin directory does not exist" do
+    Dir.mktmpdir do |dir|
+      warn_obj = make_warn_obj
+      check = LanguagePack::Helpers::BundleBinstubCheck.new(
+        app_root_dir: dir,
+        warn_object: warn_obj
+      )
+      check.call
+
+      expect(warn_obj.msg).to be_nil
+    end
+  end
+end
diff --git a/spec/helpers/bundle_list_spec.rb b/spec/helpers/bundle_list_spec.rb
new file mode 100644
index 000000000..3cdb68917
--- /dev/null
+++ b/spec/helpers/bundle_list_spec.rb
@@ -0,0 +1,50 @@
+require "spec_helper"
+
+describe "Bundle list" do
+  it "parses bundle list output" do
+    output = <<~EOF
+      Gems included by the bundle:
+        * actioncable (6.1.4.1)
+        * actionmailbox (6.1.4.1)
+        * actionmailer (6.1.4.1)
+        * actionpack (6.1.4.1)
+        * actiontext (6.1.4.1)
+        * actionview (6.1.4.1)
+        * activejob (6.1.4.1)
+        * activemodel (6.1.4.1)
+        * activerecord (6.1.4.1)
+        * activestorage (6.1.4.1)
+        * activesupport (6.1.4.1)
+        * addressable (2.8.0)
+        * ast (2.4.2)
+        * railties (6.1.4.1)
+      Use `bundle info` to print more detailed information about a gem
+    EOF
+
+    bundle_list = LanguagePack::Helpers::BundleList.new(
+      output: output
+    )
+    expect(bundle_list.has_gem?("railties")).to be_truthy
+    expect(bundle_list.gem_version("railties")).to eq(Gem::Version.new("6.1.4.1"))
+    expect(bundle_list.has_gem?("nope")).to be_falsey
+
+    expect(bundle_list.length).to eq(14)
+  end
+
+  it "handles git SHA gems" do
+    output = <<~EOF
+      Gems included by the bundle:
+        * railties (6.1.4.1 asdf1)
+      Use `bundle info` to print more detailed information about a gem
+    EOF
+
+    bundle_list = LanguagePack::Helpers::BundleList.new(
+      output: output
+    )
+    expect(bundle_list.has_gem?("railties")).to be_truthy
+    expect(bundle_list.gem_version("railties")).to eq(Gem::Version.new("6.1.4.1"))
+    expect(bundle_list.has_gem?("nope")).to be_falsey
+
+    expect(bundle_list.length).to eq(1)
+  end
+end
diff --git a/spec/helpers/bundler_wrapper_spec.rb b/spec/helpers/bundler_wrapper_spec.rb
index 8affc1f74..eb3a60454 100644
--- a/spec/helpers/bundler_wrapper_spec.rb
+++ b/spec/helpers/bundler_wrapper_spec.rb
@@ -1,19 +1,49 @@
-require 'spec_helper'
+require "spec_helper"
 
-describe "BundlerWrapper" do
+describe "Multiple platform detection" do
+  it "reports true on bundler 2.2+" do
+    Dir.mktmpdir do |dir|
+      gemfile = Pathname(dir).join("Gemfile")
+      report = HerokuBuildReport.dev_null
 
-  before(:each) do
-    @bundler = LanguagePack::Helpers::BundlerWrapper.new
+      LanguagePack::Helpers::BundlerWrapper.new(
+        bundler_path: Dir.mktmpdir,
+        bundler_version: "2.5.7",
+        gemfile_path: gemfile,
+        report: report
+      )
+      expect(report.data).to eq(
+        {
+          "dot_ruby_version.contents" => nil,
+          "bundler.major" => "2",
+          "bundler.minor" => "5",
+          "bundler.patch" => "7",
+          "bundler.version_installed" => "2.5.7"
+        }
+      )
+    end
   end
+end
 
-  after(:each) do
-    @bundler.clean
-  end
+describe "BundlerWrapper" do
+  it "handles windows BUNDLED WITH" do
+    Dir.mktmpdir do |dir|
+      tmp_dir = Pathname(dir)
+      FileUtils.cp_r(fixture_path("windows_lockfile/."), tmp_dir)
 
-  it "detects windows gemfiles" do
-    Hatchet::App.new("rails4_windows_mri193").in_directory do |dir|
-      expect(@bundler.install.windows_gemfile_lock?).to be_true
+      tmp_gemfile_path = tmp_dir.join("Gemfile")
+      tmp_gemfile_lock_path = tmp_dir.join("Gemfile.lock")
+
+      expect(tmp_gemfile_lock_path.read).to match("BUNDLED")
+
+      gemfile_lock = LanguagePack::Helpers::GemfileLock.new(contents: tmp_gemfile_lock_path.read)
+      wrapper = LanguagePack::Helpers::BundlerWrapper.new(
+        bundler_path: Dir.mktmpdir,
+        bundler_version: gemfile_lock.bundler.version,
+        gemfile_path: tmp_gemfile_path
+      )
+
+      expect(wrapper.version).to eq("2.0.2")
     end
   end
 end
-
diff --git a/spec/helpers/config_spec.rb b/spec/helpers/config_spec.rb
new file mode 100644
index 000000000..2b90347bb
--- /dev/null
+++ b/spec/helpers/config_spec.rb
@@ -0,0 +1,17 @@
+require "spec_helper"
+
+describe "Boot Strap Config" do
+  it "matches toml config" do
+    require "toml-rb"
+    config = TomlRB.load_file("buildpack.toml")
+    bootstrap_version = config["buildpack"]["ruby_version"]
+    expect(bootstrap_version).to eq(LanguagePack::RubyVersion::BOOTSTRAP_VERSION_NUMBER)
+
+    expect(`ruby -v`).to match(Regexp.escape(LanguagePack::RubyVersion::BOOTSTRAP_VERSION_NUMBER))
+
+    ci_task = Pathname(".github").join("workflows").join("hatchet_app_cleaner.yml").read
+    ci_task_yml = YAML.load(ci_task)
+    task = ci_task_yml["jobs"]["hatchet-app-cleaner"]["steps"].detect { |step| step["uses"].match?(/ruby\/setup-ruby/) } or raise "Not found"
+    expect(task["with"]["ruby-version"]).to match(LanguagePack::RubyVersion::BOOTSTRAP_VERSION_NUMBER)
+  end
+end
diff --git a/spec/helpers/default_env_vars_spec.rb b/spec/helpers/default_env_vars_spec.rb
new file mode 100644
index 000000000..b4a5a9420
--- /dev/null
+++ b/spec/helpers/default_env_vars_spec.rb
@@ -0,0 +1,151 @@
+require "spec_helper"
+
+describe LanguagePack::Helpers::DefaultEnvVars do
+  it "returns when everything falsey" do
+    env = LanguagePack::Helpers::DefaultEnvVars.call(
+      is_jruby: nil,
+      rack_version: nil,
+      rails_version: nil,
+      secret_key_base: nil,
+      environment_name: "production"
+    )
+
+    expect(env).to eq({
+      "LANG" => "en_US.UTF-8",
+      "PUMA_PERSISTENT_TIMEOUT" => "95"
+    })
+  end
+
+  it "jruby" do
+    env = LanguagePack::Helpers::DefaultEnvVars.call(
+      is_jruby: true,
+      rack_version: nil,
+      rails_version: nil,
+      secret_key_base: nil,
+      environment_name: "production"
+    )
+
+    expect(env).to eq({
+      "LANG" => "en_US.UTF-8",
+      "PUMA_PERSISTENT_TIMEOUT" => "95",
+      "JRUBY_OPTS" => "-Xcompile.invokedynamic=false"
+    })
+  end
+
+  it "rack" do
+    env = LanguagePack::Helpers::DefaultEnvVars.call(
+      is_jruby: false,
+      rack_version: Gem::Version.new("2.0.0"),
+      rails_version: nil,
+      secret_key_base: nil,
+      environment_name: "production"
+    )
+
+    expect(env).to eq({
+      "LANG" => "en_US.UTF-8",
+      "PUMA_PERSISTENT_TIMEOUT" => "95",
+      "RACK_ENV" => "production"
+    })
+  end
+
+  # if rails_version&. >= Gem::Version.new("4.1.0.beta1")
+  #   out["SECRET_KEY_BASE"] = secret_key_base
+  # end
+
+  # if rails_version&. >= Gem::Version.new("4.2.0")
+  #   out["RAILS_SERVE_STATIC_FILES"] = "enabled"
+  # end
+
+  # if rails_version&. >= Gem::Version.new("5.0.0")
+  #   out["RAILS_LOG_TO_STDOUT"] = "enabled"
+  # end
+
+  it "rails 4.1" do
+    env = LanguagePack::Helpers::DefaultEnvVars.call(
+      is_jruby: false,
+      rack_version: Gem::Version.new("2.0.0"),
+      rails_version: Gem::Version.new("4.1.0.beta1"),
+      secret_key_base: "secret_key_base",
+      environment_name: "production"
+    )
+
+    expect(env).to eq({
+      "LANG" => "en_US.UTF-8",
+      "PUMA_PERSISTENT_TIMEOUT" => "95",
+      "RACK_ENV" => "production",
+      "RAILS_ENV" => "production",
+      "SECRET_KEY_BASE" => "secret_key_base"
+    })
+  end
+
+  it "rails 4.2" do
+    env = LanguagePack::Helpers::DefaultEnvVars.call(
+      is_jruby: false,
+      rack_version: Gem::Version.new("2.0.0"),
+      rails_version: Gem::Version.new("4.2.0"),
+      secret_key_base: "secret_key_base",
+      environment_name: "production"
+    )
+
+    expect(env).to eq({
+      "LANG" => "en_US.UTF-8",
+      "PUMA_PERSISTENT_TIMEOUT" => "95",
+      "RACK_ENV" => "production",
+      "RAILS_ENV" => "production",
+      "SECRET_KEY_BASE" => "secret_key_base",
+      "RAILS_SERVE_STATIC_FILES" => "enabled"
+    })
+  end
+
+  it "rails 5.0" do
+    env = LanguagePack::Helpers::DefaultEnvVars.call(
+      is_jruby: false,
+      rack_version: Gem::Version.new("2.0.0"),
+      rails_version: Gem::Version.new("5.0.0"),
+      secret_key_base: "secret_key_base",
+      environment_name: "production"
+    )
+
+    expect(env).to eq({
+      "LANG" => "en_US.UTF-8",
+      "PUMA_PERSISTENT_TIMEOUT" => "95",
+      "RACK_ENV" => "production",
+      "RAILS_ENV" => "production",
+      "SECRET_KEY_BASE" => "secret_key_base",
+      "RAILS_SERVE_STATIC_FILES" => "enabled",
+      "RAILS_LOG_TO_STDOUT" => "enabled"
+    })
+  end
+
+  it "uses environment_name for RACK_ENV and RAILS_ENV" do
+    env = LanguagePack::Helpers::DefaultEnvVars.call(
+      is_jruby: false,
+      rack_version: Gem::Version.new("2.0.0"),
+      rails_version: Gem::Version.new("5.0.0"),
+      secret_key_base: "secret_key_base",
+      environment_name: "test"
+    )
+
+    expect(env).to eq({
+      "LANG" => "en_US.UTF-8",
+      "PUMA_PERSISTENT_TIMEOUT" => "95",
+      "RACK_ENV" => "test",
+      "RAILS_ENV" => "test",
+      "SECRET_KEY_BASE" => "secret_key_base",
+      "RAILS_SERVE_STATIC_FILES" => "enabled",
+      "RAILS_LOG_TO_STDOUT" => "enabled"
+    })
+  end
+
+  it "raises an error if secret_key_base is not provided and rails 4.1+" do
+    expect {
+      LanguagePack::Helpers::DefaultEnvVars.call(
+        is_jruby: false,
+        rack_version: Gem::Version.new("2.0.0"),
+        rails_version: Gem::Version.new("4.1.0"),
+        secret_key_base: nil,
+        environment_name: "production"
+      )
+    }.to raise_error(ArgumentError)
+  end
+end
diff --git a/spec/helpers/dot_ruby_version_file_spec.rb b/spec/helpers/dot_ruby_version_file_spec.rb
new file mode 100644
index 000000000..7154c3ce4
--- /dev/null
+++ b/spec/helpers/dot_ruby_version_file_spec.rb
@@ -0,0 +1,199 @@
+require "spec_helper"
+
+describe "DotRubyVersionFile" do
+  it "parses a plain version" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "3.4.8").call
+    expect(result.ruby_version).to be_a(LanguagePack::RubyVersion)
+    expect(result.ruby_version.ruby_version).to eq("3.4.8")
+    expect(result.ruby_version.engine).to eq(:ruby)
+    expect(result.ruby_version.engine_version).to eq("3.4.8")
+    expect(result.ruby_version.default?).to eq(false)
+    expect(result.warnings).to eq([])
+  end
+
+  it "strips ruby- prefix" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "ruby-3.4.8").call
+    expect(result.ruby_version.ruby_version).to eq("3.4.8")
+    expect(result.ruby_version.engine).to eq(:ruby)
+    expect(result.warnings).to eq([])
+  end
+
+  it "trims trailing comment" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "ruby-3.4.8 # our version").call
+    expect(result.ruby_version.ruby_version).to eq("3.4.8")
+    expect(result.warnings).to eq([])
+
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "ruby-3.4.8# our version").call
+    expect(result.ruby_version.ruby_version).to eq("3.4.8")
+    expect(result.warnings).to eq([])
+  end
+
+  it "strips @company-name suffix with ruby- prefix" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "ruby-3.4.8@company-name").call
+    expect(result.ruby_version.ruby_version).to eq("3.4.8")
+    expect(result.warnings).to eq([])
+
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "ruby-3.4.8@company=>name").call
+    expect(result.ruby_version.ruby_version).to eq("3.4.8")
+    expect(result.warnings).to eq([])
+  end
+
+  it "strips @org suffix from plain version" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "3.4.8@myorg").call
+    expect(result.ruby_version.ruby_version).to eq("3.4.8")
+    expect(result.warnings).to eq([])
+  end
+
+  it "skips comments and blank lines" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: <<~EOF).call
+      # This is a comment
+
+      3.4.8
+    EOF
+    expect(result.ruby_version.ruby_version).to eq("3.4.8")
+    expect(result.warnings).to eq([])
+  end
+
+  it "strips leading and trailing whitespace from the version line" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "  3.4.8  \n").call
+    expect(result.ruby_version.ruby_version).to eq("3.4.8")
+    expect(result.warnings).to eq([])
+  end
+
+  it "parses pre-release with dot syntax" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "3.4.0.rc1").call
+    expect(result.ruby_version.ruby_version).to eq("3.4.0")
+    expect(result.ruby_version.pre).to eq("rc1")
+    expect(result.ruby_version.version_for_download).to eq("ruby-3.4.0.rc1")
+    expect(result.warnings).to eq([])
+  end
+
+  it "normalizes pre-release dash syntax to dot syntax" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "3.4.0-preview2").call
+    expect(result.ruby_version.ruby_version).to eq("3.4.0")
+    expect(result.ruby_version.pre).to eq("preview2")
+    expect(result.ruby_version.version_for_download).to eq("ruby-3.4.0.preview2")
+    expect(result.warnings).to eq([])
+  end
+
+  it "normalizes pre-release with ruby- prefix" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "ruby-3.4.0-rc1").call
+    expect(result.ruby_version.ruby_version).to eq("3.4.0")
+    expect(result.ruby_version.pre).to eq("rc1")
+    expect(result.ruby_version.version_for_download).to eq("ruby-3.4.0.rc1")
+    expect(result.warnings).to eq([])
+  end
+
+  it "handles combined prefix strip, gemset strip, and pre-release" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "ruby-3.4.0-rc1@gemset").call
+    expect(result.ruby_version.ruby_version).to eq("3.4.0")
+    expect(result.ruby_version.pre).to eq("rc1")
+    expect(result.ruby_version.version_for_download).to eq("ruby-3.4.0.rc1")
+    expect(result.warnings).to eq([])
+  end
+
+  it "handles CRLF line endings" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "3.4.8\r\n").call
+    expect(result.ruby_version.ruby_version).to eq("3.4.8")
+    expect(result.ruby_version.version_for_download).to eq("ruby-3.4.8")
+    expect(result.warnings).to eq([])
+  end
+
+  it "is empty for an empty string" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "").call
+    expect(result.ruby_version).to be_nil
+    expect(result.warnings).to eq([])
+  end
+
+  it "is empty for only whitespace" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "   \n  \n").call
+    expect(result.ruby_version).to be_nil
+    expect(result.warnings).to eq([])
+  end
+
+  it "is empty for only comments" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "# just a comment\n# another").call
+    expect(result.ruby_version).to be_nil
+    expect(result.warnings).to eq([])
+  end
+
+  it "warns for multiple meaningful lines" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: <<~EOF).call
+      3.4.8
+      3.5.0
+    EOF
+    expect(result.ruby_version).to be_nil
+    expect(result.warnings.length).to eq(1)
+    expect(result.warnings.first).to include("multiple version lines")
+  end
+
+  it "warns for jruby" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "jruby-10.0.2.0").call
+    expect(result.ruby_version).to be_nil
+    expect(result.warnings.length).to eq(1)
+    expect(result.warnings.first).to include("JRuby")
+  end
+
+  it "warns for version specifiers with >=" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "ruby >= 3.1.6, < 3.3").call
+    expect(result.ruby_version).to be_nil
+    expect(result.warnings.length).to eq(1)
+    expect(result.warnings.first).to include("Cannot parse `.ruby-version` file, version specifiers (`>=`) are not supported.")
+  end
+
+  it "warns for ~> specifier" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "~> 3.1").call
+    expect(result.ruby_version).to be_nil
+    expect(result.warnings.length).to eq(1)
+    expect(result.warnings.first).to include("Cannot parse `.ruby-version` file, version specifiers (`~>`) are not supported.")
+  end
+
+  it "warns for >= specifier" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: ">= 3.1.6").call
+    expect(result.ruby_version).to be_nil
+    expect(result.warnings.length).to eq(1)
+    expect(result.warnings.first).to include("Cannot parse `.ruby-version` file, version specifiers (`>=`) are not supported.")
+  end
+
+  it "warns for > specifier" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "> 3.1.6").call
+    expect(result.ruby_version).to be_nil
+    expect(result.warnings.length).to eq(1)
+    expect(result.warnings.first).to include("Cannot parse `.ruby-version` file, version specifiers (`>`) are not supported.")
+  end
+
+  it "warns for < specifier" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "< 3.1.6").call
+    expect(result.ruby_version).to be_nil
+    expect(result.warnings.length).to eq(1)
+    expect(result.warnings.first).to include("Cannot parse `.ruby-version` file, version specifiers (`<`) are not supported.")
+  end
+
+  it "warns for = specifier" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "=3.1.6").call
+    expect(result.ruby_version).to be_nil
+    expect(result.warnings.length).to eq(1)
+    expect(result.warnings.first).to include("Cannot parse `.ruby-version` file, version specifiers (`=`) are not supported.")
+  end
+
+  it "warns for garbage input" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "not-a-version").call
+    expect(result.ruby_version).to be_nil
+    expect(result.warnings.length).to eq(1)
+    expect(result.warnings.first).to include("Cannot parse Ruby version from")
+  end
+
+  it "warns for two-part version like 3.4" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "3.4").call
+    expect(result.ruby_version).to be_nil
+    expect(result.warnings.length).to eq(1)
+    expect(result.warnings.first).to include("Only full Ruby versions with major, minor, and patch are supported")
+  end
+
+  it "does not crash on bare ruby- prefix" do
+    result = LanguagePack::Helpers::DotRubyVersionFile.new(contents: "ruby-").call
+    expect(result.ruby_version).to be_nil
+    expect(result.warnings.length).to eq(1)
+    expect(result.warnings.first).to include("Cannot parse Ruby version from")
+  end
+end
diff --git a/spec/helpers/download_presence_spec.rb b/spec/helpers/download_presence_spec.rb
new file mode 100644
index 000000000..c2e5aac3c
--- /dev/null
+++ b/spec/helpers/download_presence_spec.rb
@@ -0,0 +1,118 @@
+require "spec_helper"
+
+describe LanguagePack::Helpers::DownloadPresence do
+  it "handles multi-arch transitions for files that exist" do
+    download = LanguagePack::Helpers::DownloadPresence.new(
+      amd_only_stacks: ["heroku-22"],
+      file_name: "ruby-3.1.4.tgz",
+      stacks: ["heroku-22", "heroku-24"],
+      arch: "amd64"
+    )
+
+    download.call
+
+    expect(download.next_stack(current_stack: "heroku-22")).to eq("heroku-24")
+    expect(download.next_stack(current_stack: "heroku-24")).to be_falsey
+
+    expect(download.exists_on_next_stack?(current_stack: "heroku-22")).to be_truthy
+  end
+
+  it "handles multi-arch transitions for files that do not exist" do
+    download = LanguagePack::Helpers::DownloadPresence.new(
+      amd_only_stacks: [],
+      file_name: "ruby-3.0.5.tgz",
+      stacks: ["heroku-24", "heroku-26"],
+      arch: "amd64"
+    )
+
+    download.call
+
+    expect(download.next_stack(current_stack: "heroku-24")).to eq("heroku-26")
+    expect(download.next_stack(current_stack: "heroku-26")).to be_falsey
+
+    expect(download.exists_on_next_stack?(current_stack: "heroku-24")).to be_falsey
+  end
+
+  it "knows if exists on the next stack" do
+    download = LanguagePack::Helpers::DownloadPresence.new(
+      amd_only_stacks: ["heroku-22"],
+      file_name: "#{LanguagePack::RubyVersion::DEFAULT_VERSION}.tgz",
+      stacks: ["heroku-22", "heroku-24"],
+      arch: "amd64"
+    )
+
+    download.call
+
+    expect(download.next_stack(current_stack: "heroku-22")).to eq("heroku-24")
+    expect(download.next_stack(current_stack: "heroku-24")).to be_falsey
+
+    expect(download.exists_on_next_stack?(current_stack: "heroku-22")).to be_truthy
+  end
+
+  it "detects when a package is present on two stacks but not a third" do
+    download = LanguagePack::Helpers::DownloadPresence.new(
+      amd_only_stacks: ["cedar-14", "heroku-16", "heroku-18"],
+      file_name: "ruby-2.3.0.tgz",
+      stacks: ["cedar-14", "heroku-16", "heroku-18"],
+      arch: nil
+    )
+
+    download.call
+
+    expect(download.exists?).to eq(true)
+    expect(download.valid_stack_list).to eq(["cedar-14", "heroku-16"])
+  end
+
+  it "detects when a package does not exist" do
+    download = LanguagePack::Helpers::DownloadPresence.new(
+      amd_only_stacks: ["heroku-22"],
+      file_name: "does-not-exist.tgz",
+      stacks: ["heroku-22", "heroku-24"],
+      arch: nil
+    )
+
+    download.call
+
+    expect(download.exists?).to eq(false)
+    expect(download.valid_stack_list).to eq([])
+  end
+
+  it "detects default ruby version" do
+    download = LanguagePack::Helpers::DownloadPresence.new(
+      amd_only_stacks: LanguagePack::Base::AMD_ONLY_STACKS,
+      file_name: "#{LanguagePack::RubyVersion::DEFAULT_VERSION}.tgz",
+      arch: "amd64"
+    )
+
+    download.call
+
+    expect(download.exists?).to eq(true)
+    expect(download.valid_stack_list).to include("heroku-24")
+  end
+
+  it "next stack for ruby 3.0.10 from heroku-24 is heroku-26" do
+    download = LanguagePack::Helpers::DownloadPresence.new(
+      amd_only_stacks: LanguagePack::Base::AMD_ONLY_STACKS,
+      file_name: "ruby-3.0.10.tgz",
+      arch: "amd64"
+    )
+
+    download.call
+
+    expect(download.next_stack(current_stack: "heroku-24")).to eq("heroku-26")
+  end
+
+  it "handles the current stack not being in the known stacks list" do
+    download = LanguagePack::Helpers::DownloadPresence.new(
+      amd_only_stacks: LanguagePack::Base::AMD_ONLY_STACKS,
+      file_name: "#{LanguagePack::RubyVersion::DEFAULT_VERSION}.tgz",
+      arch: nil
+    )
+
+    download.call
+
+    expect(download.supported_stack?(current_stack: "unknown-stack")).to be_falsey
+    expect(download.next_stack(current_stack: "unknown-stack")).to be_nil
+    expect(download.exists_on_next_stack?(current_stack: "unknown-stack")).to be_falsey
+  end
+end
diff --git a/spec/helpers/fetcher_spec.rb b/spec/helpers/fetcher_spec.rb
deleted file mode 100644
index 03fd6d8ad..000000000
--- a/spec/helpers/fetcher_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-require 'spec_helper'
-
-describe "Fetches" do
-
-  it "bundler" do
-    Dir.mktmpdir do |dir|
-      Dir.chdir(dir) do
-        fetcher = LanguagePack::Fetcher.new(LanguagePack::Base::VENDOR_URL)
-        fetcher.fetch_untar("#{LanguagePack::Ruby::BUNDLER_GEM_PATH}.tgz")
-        expect(`ls bin`).to match("bundle")
-      end
-    end
-  end
-end
-
diff --git a/spec/helpers/gemfile_lock_spec.rb b/spec/helpers/gemfile_lock_spec.rb
new file mode 100644
index 000000000..7f7c13149
--- /dev/null
+++ b/spec/helpers/gemfile_lock_spec.rb
@@ -0,0 +1,195 @@
+require "spec_helper"
+
+describe LanguagePack::Helpers::GemfileLock do
+  it "parses empty gemfile without error" do
+    report = HerokuBuildReport.dev_null
+    gemfile_lock = LanguagePack::Helpers::GemfileLock.new(
+      report: report,
+      contents: ""
+    )
+    expect(gemfile_lock.ruby.ruby_version).to eq(nil)
+    expect(gemfile_lock.ruby.pre).to eq(nil)
+    expect(gemfile_lock.ruby.engine).to eq(:ruby)
+    expect(gemfile_lock.ruby.empty?).to eq(true)
+    expect(gemfile_lock.ruby.engine_version).to eq(nil)
+
+    expect(gemfile_lock.bundler.version).to eq(nil)
+    expect(gemfile_lock.bundler.empty?).to eq(true)
+    expect(report.data).to eq({"gemfile_lock.bundled_with.empty" => true})
+  end
+
+  it "records invalid parsing" do
+    report = HerokuBuildReport.dev_null
+    LanguagePack::Helpers::GemfileLock.new(
+      report: report,
+      contents: <<~EOF
+        RUBY VERSION
+        ruby 3.3.5p100
+        BUNDLED WITH
+        2.3.4
+      EOF
+    )
+    expect(
+      report.data["gemfile_lock.bundler_version.failed_parse"]
+    ).to eq(true)
+    expect(
+      report.data["gemfile_lock.bundler_version.failed_contents"]
+    ).to eq(<<~EOF.strip)
+      BUNDLED WITH
+      2.3.4
+    EOF
+
+    expect(
+      report.data["gemfile_lock.ruby_version.failed_parse"]
+    ).to eq(true)
+    expect(
+      report.data["gemfile_lock.ruby_version.failed_contents"]
+    ).to eq(<<~EOF.strip)
+      RUBY VERSION
+      ruby 3.3.5p100
+    EOF
+  end
+
+  it "captures MRI version and ignores patchlevel" do
+    gemfile_lock = LanguagePack::Helpers::GemfileLock.new(
+      contents: <<~EOF
+        RUBY VERSION
+           ruby 3.3.5p100
+        BUNDLED WITH
+           2.3.4
+      EOF
+    )
+    expect(gemfile_lock.ruby.ruby_version).to eq("3.3.5")
+    expect(gemfile_lock.ruby.pre).to eq(nil)
+    expect(gemfile_lock.ruby.engine).to eq(:ruby)
+    expect(gemfile_lock.ruby.empty?).to eq(false)
+    expect(gemfile_lock.ruby.engine_version).to eq("3.3.5")
+
+    expect(gemfile_lock.bundler.version).to eq("2.3.4")
+    expect(gemfile_lock.bundler.empty?).to eq(false)
+  end
+
+  it "works with windows line endings" do
+    gemfile_lock = LanguagePack::Helpers::GemfileLock.new(
+      contents: <<~EOF.gsub("\n", "\r\n")
+        RUBY VERSION
+           ruby 3.3.5p100
+        BUNDLED WITH
+           2.3.4
+      EOF
+    )
+    expect(gemfile_lock.ruby.ruby_version).to eq("3.3.5")
+    expect(gemfile_lock.ruby.pre).to eq(nil)
+    expect(gemfile_lock.ruby.engine).to eq(:ruby)
+    expect(gemfile_lock.ruby.empty?).to eq(false)
+    expect(gemfile_lock.ruby.engine_version).to eq("3.3.5")
+
+    expect(gemfile_lock.bundler.version).to eq("2.3.4")
+    expect(gemfile_lock.bundler.empty?).to eq(false)
+  end
+
+  it "captures jruby version" do
+    gemfile_lock = LanguagePack::Helpers::GemfileLock.new(
+      contents: <<~EOF
+        GEM
+          remote: https://rubygems.org/
+          specs:
+        PLATFORMS
+          java
+        RUBY VERSION
+           ruby 2.5.7p001 (jruby 9.2.13.0)
+      EOF
+    )
+    expect(gemfile_lock.ruby.ruby_version).to eq("2.5.7")
+    expect(gemfile_lock.ruby.pre).to eq(nil)
+    expect(gemfile_lock.ruby.engine).to eq(:jruby)
+    expect(gemfile_lock.ruby.empty?).to eq(false)
+    expect(gemfile_lock.ruby.engine_version).to eq("9.2.13.0")
+  end
+
+  it "is resiliant to gemfile.lock format changes" do
+    gemfile_lock = LanguagePack::Helpers::GemfileLock.new(
+      contents: <<~EOF
+        GEM
+          remote: https://rubygems.org/
+          specs:
+        # Pretend format change
+        METADATA
+          (jruby 9)
+        PLATFORMS
+          java
+        RUBY VERSION
+           ruby 2.5.7p001 (jruby 9.2.13.0)
+      EOF
+    )
+    expect(gemfile_lock.ruby.ruby_version).to eq("2.5.7")
+    expect(gemfile_lock.ruby.pre).to eq(nil)
+    expect(gemfile_lock.ruby.engine).to eq(:jruby)
+    expect(gemfile_lock.ruby.empty?).to eq(false)
+    expect(gemfile_lock.ruby.engine_version).to eq("9.2.13.0")
+  end
+
+  it "handles RC dot syntax" do
+    gemfile_lock = LanguagePack::Helpers::GemfileLock.new(
+      contents: <<~EOF
+        RUBY VERSION
+           ruby 3.4.0.rc1
+        BUNDLED WITH
+           2.3.4
+      EOF
+    )
+    expect(gemfile_lock.ruby.ruby_version).to eq("3.4.0")
+    expect(gemfile_lock.ruby.pre).to eq("rc1")
+    expect(gemfile_lock.ruby.engine).to eq(:ruby)
+    expect(gemfile_lock.ruby.empty?).to eq(false)
+    expect(gemfile_lock.ruby.engine_version).to eq("3.4.0")
+  end
+
+  it "handles pre without a number" do
+    gemfile_lock = LanguagePack::Helpers::GemfileLock.new(
+      contents: <<~EOF
+        RUBY VERSION
+           ruby 3.4.0.lol
+        BUNDLED WITH
+           2.3.4
+      EOF
+    )
+    expect(gemfile_lock.ruby.ruby_version).to eq("3.4.0")
+    expect(gemfile_lock.ruby.pre).to eq("lol")
+    expect(gemfile_lock.ruby.engine).to eq(:ruby)
+    expect(gemfile_lock.ruby.empty?).to eq(false)
+    expect(gemfile_lock.ruby.engine_version).to eq("3.4.0")
+  end
+
+  it "handles preview dot syntax" do
+    gemfile_lock = LanguagePack::Helpers::GemfileLock.new(
+      contents: <<~EOF
+        RUBY VERSION
+           ruby 3.4.0.preview2
+        BUNDLED WITH
+           2.3.4
+      EOF
+    )
+    expect(gemfile_lock.ruby.ruby_version).to eq("3.4.0")
+    expect(gemfile_lock.ruby.pre).to eq("preview2")
+    expect(gemfile_lock.ruby.engine).to eq(:ruby)
+    expect(gemfile_lock.ruby.empty?).to eq(false)
+    expect(gemfile_lock.ruby.engine_version).to eq("3.4.0")
+  end
+
+  it "handles Bundler 4 style" do
+    gemfile_lock = LanguagePack::Helpers::GemfileLock.new(
+      contents: <<~EOF
+        RUBY VERSION
+          ruby 3.4.0
+        BUNDLED WITH
+          2.3.4
+      EOF
+    )
+    expect(gemfile_lock.ruby.ruby_version).to eq("3.4.0")
+    expect(gemfile_lock.ruby.pre).to eq(nil)
+    expect(gemfile_lock.ruby.engine).to eq(:ruby)
+    expect(gemfile_lock.ruby.empty?).to eq(false)
+    expect(gemfile_lock.ruby.engine_version).to eq("3.4.0")
+  end
+end
diff --git a/spec/helpers/heroku_build_report_spec.rb b/spec/helpers/heroku_build_report_spec.rb
new file mode 100644
index 000000000..f3f1ab0ba
--- /dev/null
+++ b/spec/helpers/heroku_build_report_spec.rb
@@ -0,0 +1,72 @@
+require "spec_helper"
+
+describe "Build report" do
+  it "loads previously written report" do
+    Dir.mktmpdir do |dir|
+      path = Pathname(dir).join(".report.json").tap { |p| p.write('{ "prior": true }') }
+      io = StringIO.new
+      report = HerokuBuildReport::JsonReport.new(
+        io: io,
+        path: path
+      )
+      report.capture("key" => "value")
+      expect(report.data).to eq({"prior" => true, "key" => "value"})
+    end
+  end
+
+  it "handles malformed json" do
+    Dir.mktmpdir do |dir|
+      path = Pathname(dir).join(".report.json").tap { |p| p.write("zomg") }
+      io = StringIO.new
+      report = HerokuBuildReport::JsonReport.new(
+        io: io,
+        path: path
+      )
+      report.capture("key" => "value")
+      expect(report.data).to eq({"build_report_file_malformed" => true, "key" => "value"})
+    end
+  end
+
+  it "handles complex object serialization by converting them to strings" do
+    Dir.mktmpdir do |dir|
+      path = Pathname(dir).join(".report.json")
+      report = HerokuBuildReport::JsonReport.new(
+        path: path
+      )
+      value = Gem::Version.new("3.4.2")
+      expect(report.complex_object?(value)).to eq(true)
+      expect(value.to_yaml).to_not eq(value.to_s.to_yaml)
+      report.capture("key" => value)
+
+      expect(report.data).to eq({"key" => "3.4.2"})
+      expect(path.read.strip).to eq(<<~EOF.strip)
+        {"key":"3.4.2"}
+      EOF
+    end
+  end
+
+  it "writes valid json" do
+    Dir.mktmpdir do |dir|
+      path = Pathname(dir).join(".report.json")
+      report = HerokuBuildReport::JsonReport.new(
+        path: path
+      )
+      report.capture(
+        "string" => "'with single quotes'",
+        "string_plain" => "plain",
+        "number" => 22,
+        "boolean" => true
+      )
+
+      parsed = JSON.parse(path.read).sort_by { |k, _| k }.to_h
+      expect(parsed).to eq(
+        {
+          "string" => "'with single quotes'",
+          "string_plain" => "plain",
+          "number" => 22,
+          "boolean" => true
+        }
+      )
+    end
+  end
+end
diff --git a/spec/helpers/heroku_ruby_installer_spec.rb b/spec/helpers/heroku_ruby_installer_spec.rb
new file mode 100644
index 000000000..7d78e52fc
--- /dev/null
+++ b/spec/helpers/heroku_ruby_installer_spec.rb
@@ -0,0 +1,136 @@
+require "spec_helper"
+
+describe LanguagePack::Installers::HerokuRubyInstaller do
+  def installer(app_path:, report: HerokuBuildReport::GLOBAL, env: {})
+    LanguagePack::Installers::HerokuRubyInstaller.new(
+      amd_only_stacks: LanguagePack::Base::AMD_ONLY_STACKS,
+      stack: "heroku-24",
+      arch: "amd64",
+      app_path: app_path,
+      report: report,
+      env: env
+    )
+  end
+
+  def sort_hash(hash)
+    hash.sort_by { |k, _| k.to_s }.to_h
+  end
+
+  def ruby_version
+    LanguagePack::RubyVersion.default(last_version: "3.1.7")
+  end
+
+  describe "#fetch_unpack" do
+    it "should fetch and unpack mri" do
+      Dir.mktmpdir do |dir|
+        Dir.chdir(dir) do
+          installer(app_path: dir).fetch_unpack(ruby_version, dir)
+
+          expect(File).to exist("bin/ruby")
+        end
+      end
+    end
+  end
+
+  describe "ruby installation" do
+    it "should install ruby and setup binstubs" do
+      Dir.mktmpdir do |dir|
+        Dir.chdir(dir) do
+          report = HerokuBuildReport.dev_null
+          installer(app_path: Pathname(dir).expand_path, report: report).install(ruby_version, "#{dir}/vendor/ruby")
+
+          expect(File.symlink?("#{dir}/bin/ruby")).to be true
+          expect(File.symlink?("#{dir}/bin/ruby.exe")).to be true
+          expect(File).to exist("#{dir}/vendor/ruby/bin/ruby")
+
+          expect(File.readlink("#{dir}/bin/ruby")).to eq("../vendor/ruby/bin/ruby")
+
+          expected = {
+            "ruby_version_engine" => :ruby,
+            "ruby_version_full" => "3.1.7",
+            "ruby_version_major_minor" => "3.1",
+            "ruby_version_origin" => "default",
+            "ruby_version_unique" => "ruby-3.1.7"
+          }
+
+          expect(sort_hash(report.data)).to eq(sort_hash(expected))
+        end
+      end
+    end
+
+    it "should work with pre-release versions" do
+      Dir.mktmpdir do |dir|
+        Dir.chdir(dir) do
+          dir = Pathname(dir).expand_path
+          report = HerokuBuildReport.dev_null
+          env = {"PATH" => "priorpath"}
+          gemfile_lock = LanguagePack::Helpers::GemfileLock.new(report: report, contents: <<~EOF)
+            RUBY VERSION
+               ruby 3.5.0.preview1
+          EOF
+          installer(app_path: dir, report: report, env: env).install(
+            LanguagePack::RubyVersion.from_gemfile_lock(ruby: gemfile_lock.ruby),
+            "#{dir}/vendor/ruby"
+          )
+
+          expect(File.symlink?("#{dir}/bin/ruby")).to be true
+          expect(File.symlink?("#{dir}/bin/ruby.exe")).to be true
+          expect(File).to exist("#{dir}/vendor/ruby/bin/ruby")
+
+          expected = {
+            "ruby_version_engine" => :ruby,
+            "ruby_version_major_minor" => "3.5",
+            "ruby_version_full" => "3.5.0.preview1",
+            "ruby_version_origin" => "Gemfile.lock",
+            "ruby_version_unique" => "ruby-3.5.0.preview1",
+            "gemfile_lock.bundled_with.empty" => true
+          }
+
+          expect(sort_hash(report.data)).to eq(sort_hash(expected))
+          expect(env).to eq({"PATH" => "#{dir.join("vendor/ruby/bin")}:priorpath"})
+        end
+      end
+    end
+
+    it "should report jruby correctly" do
+      Dir.mktmpdir do |dir|
+        Dir.chdir(dir) do
+          dir = Pathname(dir).expand_path
+          report = HerokuBuildReport.dev_null
+          gemfile_lock = LanguagePack::Helpers::GemfileLock.new(report: report, contents: <<~EOF)
+            RUBY VERSION
+               ruby 3.1.4p001 (jruby 9.4.9.0)
+          EOF
+
+          env = {"PATH" => "priorpath"}
+
+          LanguagePack::Installers::HerokuRubyInstaller.new(
+            amd_only_stacks: LanguagePack::Base::AMD_ONLY_STACKS,
+            stack: "heroku-24",
+            arch: "arm64",
+            app_path: dir,
+            report: report,
+            env: env
+          ).install(
+            LanguagePack::RubyVersion.from_gemfile_lock(ruby: gemfile_lock.ruby),
+            "#{dir}/vendor/ruby"
+          )
+
+          expected = {
+            "ruby_version_engine" => :jruby,
+            "jruby_version_full" => "9.4.9.0",
+            "jruby_version_major_minor" => "9.4",
+            "jruby_version_ruby_version" => "3.1.4",
+            "ruby_version_origin" => "Gemfile.lock",
+            "ruby_version_unique" => "ruby-3.1.4-jruby-9.4.9.0",
+            "gemfile_lock.bundled_with.empty" => true
+          }
+
+          expect(sort_hash(report.data)).to eq(sort_hash(expected))
+
+          expect(env).to eq({"JRUBY_OPTS" => nil, "PATH" => "#{dir.join("vendor/ruby/bin")}:priorpath"})
+        end
+      end
+    end
+  end
+end
diff --git a/spec/helpers/lockfile_shell_parser_spec.rb b/spec/helpers/lockfile_shell_parser_spec.rb
new file mode 100644
index 000000000..dce27893c
--- /dev/null
+++ b/spec/helpers/lockfile_shell_parser_spec.rb
@@ -0,0 +1,111 @@
+require "spec_helper"
+
+describe LanguagePack::Helpers::LockfileShellParser do
+  describe ".call" do
+    it "parses gem specs from a Gemfile.lock" do
+      Dir.mktmpdir do |dir|
+        lockfile_path = Pathname(dir).join("Gemfile.lock")
+        lockfile_path.write(<<~EOF)
+          GEM
+            remote: https://rubygems.org/
+            specs:
+              rake (13.2.1)
+
+          PLATFORMS
+            arm64-darwin-22
+            ruby
+            x86_64-linux
+
+          DEPENDENCIES
+            rake
+
+          RUBY VERSION
+             ruby 3.3.9
+
+          BUNDLED WITH
+             2.7.9
+        EOF
+
+        specs = LanguagePack::Helpers::LockfileShellParser.call(lockfile_path: lockfile_path)
+
+        expect(specs["rake"]).to eq(Gem::Version.new("13.2.1"))
+      end
+    end
+
+    it "reports error on nil input" do
+      expect {
+        LanguagePack::Helpers::LockfileShellParser.call(lockfile_path: nil)
+      }.to raise_error(StandardError, /no implicit conversion of nil into String/)
+    end
+
+    it "reports error on file that does not exist" do
+      expect {
+        LanguagePack::Helpers::LockfileShellParser.call(lockfile_path: "does-not-exist.lock")
+      }.to raise_error(StandardError, /No such file or directory/)
+    end
+
+    it "reports error on invalid lockfile contents" do
+      Dir.mktmpdir do |dir|
+        lockfile_path = Pathname(dir).join("Gemfile.lock").tap { |p|
+          # Write invalid UTF-8 bytes to trigger Bundler::LockfileError
+          p.binwrite("\xff\xfe")
+        }
+        expect {
+          LanguagePack::Helpers::LockfileShellParser.call(lockfile_path: lockfile_path)
+        }.to raise_error(StandardError, /Your lockfile is unreadable/)
+      end
+    end
+
+    it "parses multiple gems from a Gemfile.lock" do
+      Dir.mktmpdir do |dir|
+        lockfile_path = Pathname(dir).join("Gemfile.lock")
+        lockfile_path.write(<<~EOF)
+          GEM
+            remote: https://rubygems.org/
+            specs:
+              concurrent-ruby (1.2.3)
+              i18n (1.14.1)
+                concurrent-ruby (~> 1.0)
+              rack (3.0.8)
+
+          PLATFORMS
+            ruby
+
+          DEPENDENCIES
+            i18n
+            rack
+
+          BUNDLED WITH
+             2.7.9
+        EOF
+
+        specs = LanguagePack::Helpers::LockfileShellParser.call(lockfile_path: lockfile_path)
+
+        expect(specs["concurrent-ruby"]).to eq(Gem::Version.new("1.2.3"))
+        expect(specs["i18n"]).to eq(Gem::Version.new("1.14.1"))
+        expect(specs["rack"]).to eq(Gem::Version.new("3.0.8"))
+      end
+    end
+
+    it "returns an empty hash for a lockfile with no gems" do
+      Dir.mktmpdir do |dir|
+        lockfile_path = Pathname(dir).join("Gemfile.lock")
+        lockfile_path.write(<<~EOF)
+          GEM
+            remote: https://rubygems.org/
+            specs:
+
+          PLATFORMS
+            ruby
+
+          BUNDLED WITH
+             2.7.9
+        EOF
+
+        specs = LanguagePack::Helpers::LockfileShellParser.call(lockfile_path: lockfile_path)
+
+        expect(specs).to eq({})
+      end
+    end
+  end
+end
diff --git a/spec/helpers/metadata_spec.rb b/spec/helpers/metadata_spec.rb
new file mode 100644
index 000000000..75636a139
--- /dev/null
+++ b/spec/helpers/metadata_spec.rb
@@ -0,0 +1,36 @@
+require "spec_helper"
+
+describe "Metadata" do
+  it "can read and write to the metadata" do
+    Dir.mktmpdir do |dir|
+      metadata = LanguagePack::Metadata.new(cache_path: dir)
+      expect(metadata.empty?).to be_truthy
+
+      expect(metadata.try_read("test")).to be_nil
+      expect(metadata.exists?("test")).to be_falsey
+      metadata.write("test", "test")
+
+      expect(metadata.try_read("test")).to eq("test")
+      expect(metadata.exists?("test")).to be_truthy
+      expect(metadata.read("test")).to eq("test")
+      expect(metadata.empty?).to be_falsey
+    end
+  end
+
+  it "can write a value conditionally" do
+    Dir.mktmpdir do |dir|
+      metadata = LanguagePack::Metadata.new(cache_path: dir)
+      called = false
+
+      expect(metadata.empty?).to be_truthy
+      expect(metadata.exists?("test")).to be_falsey
+      metadata.fetch("test") do
+        called = true
+        "test"
+      end
+      expect(metadata.read("test")).to eq("test")
+      expect(called).to be_truthy
+      expect(metadata.empty?).to be_falsey
+    end
+  end
+end
diff --git a/spec/helpers/node_installer_spec.rb b/spec/helpers/node_installer_spec.rb
new file mode 100644
index 000000000..9da9941d2
--- /dev/null
+++ b/spec/helpers/node_installer_spec.rb
@@ -0,0 +1,18 @@
+require "spec_helper"
+
+describe LanguagePack::Helpers::NodeInstaller do
+  describe "#install" do
+    LanguagePack::Base::KNOWN_ARCHITECTURES.each do |arch|
+      it "should extract a node binary on #{arch}" do
+        Dir.mktmpdir do |dir|
+          Dir.chdir(dir) do
+            installer = LanguagePack::Helpers::NodeInstaller.new(arch: "arm64")
+            installer.install
+
+            expect(File.exist?("node")).to be(true)
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/spec/helpers/nodebin_spec.rb b/spec/helpers/nodebin_spec.rb
new file mode 100644
index 000000000..79aabd206
--- /dev/null
+++ b/spec/helpers/nodebin_spec.rb
@@ -0,0 +1,13 @@
+require "spec_helper"
+
+describe LanguagePack::Helpers::Nodebin do
+  describe ".yarn" do
+    it "downloads Yarn from the npm registry (not the heroku-nodebin S3 bucket)" do
+      url = LanguagePack::Helpers::Nodebin.yarn["url"]
+
+      expect(url).to include("registry.npmjs.org")
+      expect(url).to_not include("heroku-nodebin")
+      expect(url).to eq("https://registry.npmjs.org/yarn/-/yarn-#{LanguagePack::Helpers::Nodebin::YARN_VERSION}.tgz")
+    end
+  end
+end
diff --git a/spec/helpers/outdated_ruby_version_spec.rb b/spec/helpers/outdated_ruby_version_spec.rb
new file mode 100644
index 000000000..5487afdf7
--- /dev/null
+++ b/spec/helpers/outdated_ruby_version_spec.rb
@@ -0,0 +1,137 @@
+require "spec_helper"
+
+describe LanguagePack::Helpers::OutdatedRubyVersion do
+  let(:stack) { "heroku-16" }
+  let(:fetcher) {
+    LanguagePack::Fetcher.new(LanguagePack::Base::VENDOR_URL, stack: stack)
+  }
+
+  it "handles amd ↗� architecture on heroku-24" do
+    ruby_version = LanguagePack::RubyVersion.default(last_version: "3.1.0")
+    fetcher = LanguagePack::Fetcher.new(
+      LanguagePack::Base::VENDOR_URL,
+      stack: "heroku-24",
+      arch: "amd64"
+    )
+    outdated = LanguagePack::Helpers::OutdatedRubyVersion.new(
+      current_ruby_version: ruby_version,
+      fetcher: fetcher
+    )
+
+    outdated.call
+    expect(outdated.suggested_ruby_minor_version).to eq("3.1.7")
+  end
+
+  it "handles arm 💪 architecture on heroku-24" do
+    ruby_version = LanguagePack::RubyVersion.default(last_version: "3.1.0")
+    fetcher = LanguagePack::Fetcher.new(
+      LanguagePack::Base::VENDOR_URL,
+      stack: "heroku-24",
+      arch: "arm64"
+    )
+    outdated = LanguagePack::Helpers::OutdatedRubyVersion.new(
+      current_ruby_version: ruby_version,
+      fetcher: fetcher
+    )
+
+    outdated.call
+    expect(outdated.suggested_ruby_minor_version).to eq("3.1.7")
+  end
+
+  it "finds the latest version on a stack" do
+    ruby_version = LanguagePack::RubyVersion.default(last_version: "2.2.5")
+    outdated = LanguagePack::Helpers::OutdatedRubyVersion.new(
+      current_ruby_version: ruby_version,
+      fetcher: fetcher
+    )
+
+    outdated.call
+    expect(outdated.suggested_ruby_minor_version).to eq("2.2.10")
+    expect(outdated.eol?).to eq(true)
+    expect(outdated.maybe_eol?).to eq(true)
+  end
+
+  it "detects returns original ruby version when using the latest" do
+    ruby_version = LanguagePack::RubyVersion.default(last_version: "2.2.10")
+    outdated = LanguagePack::Helpers::OutdatedRubyVersion.new(
+      current_ruby_version: ruby_version,
+      fetcher: fetcher
+    )
+
+    outdated.call
+    expect(outdated.suggested_ruby_minor_version).to eq("2.2.10")
+    expect(outdated.latest_minor_version?).to be_truthy
+  end
+
+  it "recommends a non EOL version of Ruby" do
+    ruby_version_one = LanguagePack::RubyVersion.default(last_version: "2.1.10")
+    ruby_version_two = LanguagePack::RubyVersion.default(last_version: "2.2.10")
+
+    outdated_one = LanguagePack::Helpers::OutdatedRubyVersion.new(
+      current_ruby_version: ruby_version_one,
+      fetcher: fetcher
+    )
+    outdated_two = LanguagePack::Helpers::OutdatedRubyVersion.new(
+      current_ruby_version: ruby_version_two,
+      fetcher: fetcher
+    )
+
+    outdated_one.call
+    outdated_two.call
+
+    expect(outdated_one.eol?).to be_truthy
+    expect(outdated_one.maybe_eol?).to be_truthy
+
+    expect(outdated_two.eol?).to be_truthy
+    expect(outdated_one.maybe_eol?).to be_truthy
+
+    suggested_one = outdated_one.suggest_ruby_eol_version
+    expect(suggested_one).to eq(outdated_two.suggest_ruby_eol_version)
+    expect(suggested_one[-1]).to eq("x") # i.e. 2.5.x
+
+    actual = Gem::Version.new(suggested_one)
+    expect(actual).to be > Gem::Version.new("2.4.x")
+  end
+
+  it "does not recommend EOL for recent ruby version" do
+    ruby_version = LanguagePack::RubyVersion.default(last_version: "2.2.10")
+
+    outdated = LanguagePack::Helpers::OutdatedRubyVersion.new(
+      current_ruby_version: ruby_version,
+      fetcher: fetcher
+    )
+
+    outdated.call
+
+    good_version = outdated.suggest_ruby_eol_version.sub("x", "0")
+    ruby_version = LanguagePack::RubyVersion.default(last_version: good_version)
+
+    outdated = LanguagePack::Helpers::OutdatedRubyVersion.new(
+      current_ruby_version: ruby_version,
+      fetcher: fetcher
+    )
+    outdated.call
+
+    expect(outdated.eol?).to be_falsey
+    expect(outdated.maybe_eol?).to be_falsey
+  end
+
+  it "can call eol? on the latest Ruby version" do
+    ruby_version = LanguagePack::RubyVersion.default(last_version: "2.6.0")
+
+    new_fetcher = fetcher.dup
+    def new_fetcher.exists?(value)
+      false
+    end
+
+    outdated = LanguagePack::Helpers::OutdatedRubyVersion.new(
+      current_ruby_version: ruby_version,
+      fetcher: new_fetcher
+    )
+
+    outdated.call
+
+    expect(outdated.eol?).to be_falsey
+    expect(outdated.maybe_eol?).to be_falsey
+  end
+end
diff --git a/spec/helpers/puma_warn_error_spec.rb b/spec/helpers/puma_warn_error_spec.rb
new file mode 100644
index 000000000..4a9f469fc
--- /dev/null
+++ b/spec/helpers/puma_warn_error_spec.rb
@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+describe LanguagePack::Helpers::PumaWarnError do
+  it "warns about Router 2.0 compatibility" do
+    puma_warn_error = LanguagePack::Helpers::PumaWarnError.new(
+      puma_version: Gem::Version.new("6.0.0"),
+      env: {}
+    )
+    expect(puma_warn_error.warnings.join).to include("Heroku recommends using Puma 7.0.3+ for compatibility with Router 2.0")
+  end
+
+  it "errors if incompatible version with persistent timeout env var" do
+    puma_warn_error = LanguagePack::Helpers::PumaWarnError.new(
+      puma_version: Gem::Version.new("7.0.0"),
+      env: {}
+    )
+    expect(puma_warn_error.error).to include("known issue with the `PUMA_PERSISTENT_TIMEOUT`")
+
+    puma_warn_error = LanguagePack::Helpers::PumaWarnError.new(
+      puma_version: Gem::Version.new("7.0.1"),
+      env: {}
+    )
+    expect(puma_warn_error.error).to include("known issue with the `PUMA_PERSISTENT_TIMEOUT`")
+
+    puma_warn_error = LanguagePack::Helpers::PumaWarnError.new(
+      puma_version: Gem::Version.new("7.0.2"),
+      env: {}
+    )
+    expect(puma_warn_error.error).to include("known issue with the `PUMA_PERSISTENT_TIMEOUT`")
+
+    puma_warn_error = LanguagePack::Helpers::PumaWarnError.new(
+      puma_version: Gem::Version.new("7.0.3"),
+      env: {}
+    )
+    expect(puma_warn_error.error).to be_nil
+    expect(puma_warn_error.warnings).to eq([])
+  end
+
+  it "warns, but does not error if customer manually set PUMA_PERSISTENT_TIMEOUT" do
+    puma_warn_error = LanguagePack::Helpers::PumaWarnError.new(
+      puma_version: Gem::Version.new("7.0.0"),
+      env: {"PUMA_PERSISTENT_TIMEOUT" => "95"}
+    )
+    expect(puma_warn_error.error).to be_nil
+    expect(puma_warn_error.warnings.join).to include("Heroku recommends using Puma 7.0.3+ for compatibility with Router 2.0")
+  end
+end
diff --git a/spec/helpers/rails_runner_spec.rb b/spec/helpers/rails_runner_spec.rb
new file mode 100644
index 000000000..b3c963065
--- /dev/null
+++ b/spec/helpers/rails_runner_spec.rb
@@ -0,0 +1,156 @@
+require "spec_helper"
+
+describe "Rails Runner" do
+  def isolate(&block)
+    # Process and disk isolation
+    Hatchet::App.new("default_ruby").in_directory_fork do
+      ENV["PATH"]
+      ENV["PATH"] = "./bin/:#{ENV["PATH"]}"
+
+      Dir.mktmpdir do |tmpdir|
+        Dir.chdir(tmpdir) do
+          block.call
+        end
+      end
+    end
+  end
+
+  it "config objects build propperly formatted commands" do
+    isolate do
+      rails_runner = LanguagePack::Helpers::RailsRunner.new
+      rails_runner.detect("active_storage.service")
+
+      expected = 'rails runner "begin; puts %Q{heroku.detecting.config.for.active_storage.service=#{Rails.application.config.try(:active_storage).try(:service)}}; rescue => e; end;"' # standard:disable Lint/InterpolationCheck
+      expect(rails_runner.command).to eq(expected)
+
+      rails_runner.detect("assets.compile")
+
+      expected = 'rails runner "begin; puts %Q{heroku.detecting.config.for.active_storage.service=#{Rails.application.config.try(:active_storage).try(:service)}}; rescue => e; end; begin; puts %Q{heroku.detecting.config.for.assets.compile=#{Rails.application.config.try(:assets).try(:compile)}}; rescue => e; end;"' # standard:disable Lint/InterpolationCheck
+      expect(rails_runner.command).to eq(expected)
+    end
+  end
+
+  it "calls run through child object" do
+    isolate do
+      rails_runner = LanguagePack::Helpers::RailsRunner.new
+      def rails_runner.call
+        @called ||= 0
+        @called += 1
+        ""
+      end
+
+      def rails_runner.called
+        @called
+      end
+
+      local_storage = rails_runner.detect("active_storage.service")
+      local_storage.success?
+      expect(rails_runner.called).to eq(1)
+
+      local_storage.success?
+      local_storage.did_match?("foo")
+      expect(rails_runner.called).to eq(1)
+    end
+  end
+
+  it "calls a mock interface" do
+    isolate do
+      mock_rails_runner
+      expect(File.executable?("bin/rails")).to eq(true)
+
+      rails_runner = LanguagePack::Helpers::RailsRunner.new
+      rails_runner.detect("active_storage.service")
+      rails_runner.detect("foo.bar")
+
+      expect(rails_runner.output).to match("heroku.detecting.config.for.active_storage.service=active_storage.service")
+      expect(rails_runner.output).to match("heroku.detecting.config.for.foo.bar=foo.bar")
+      expect(rails_runner.success?).to be(true)
+    end
+  end
+
+  it "timeout works as expected" do
+    isolate do
+      mock_rails_runner("pid = Process.spawn('sleep 5'); Process.wait(pid)")
+
+      diff = time_it do
+        rails_runner = LanguagePack::Helpers::RailsRunner.new(false, 0.01)
+        rails_runner.detect("active_storage.service")
+        expect(rails_runner.success?).to eq(false)
+        expect(rails_runner.timeout?).to eq(true)
+      end
+
+      expect(diff < 1).to eq(true), "expected time difference #{diff} to be less than 1 second, but was longer"
+    end
+  end
+
+  it "failure in one task does not cause another to fail" do
+    isolate do
+      mock_rails_runner('raise "bad" if value == :bad')
+
+      rails_runner = LanguagePack::Helpers::RailsRunner.new(false, 15)
+      bad_value = rails_runner.detect("bad.value")
+      local_storage = rails_runner.detect("active_storage.service")
+
+      expect(!!bad_value.success?).to eq(false)
+      expect(!!local_storage.success?).to eq(true)
+    end
+  end
+
+  it "does not fail when there is an invalid byte sequence" do
+    isolate do
+      mock_rails_runner('puts "hi \255"')
+
+      rails_runner = LanguagePack::Helpers::RailsRunner.new
+      local_storage = rails_runner.detect("active_storage.service")
+
+      expect(local_storage.success?).to be_truthy
+    end
+  end
+
+  def time_it
+    start = Time.now
+    yield
+    Time.now - start
+  end
+
+  def mock_rails_runner(try_code = "")
+    executable_contents = <<~FILE
+      #!/usr/bin/env ruby
+      require 'ostruct'
+
+      module Rails; end
+      def Rails.application
+        OpenStruct.new(config: TryMock.new) # Rails.application.config #=> TryMock instance
+      end
+
+      # Mock object used to record calls
+      # for example:
+      #
+      #   obj = Try.new
+      #   obj.try(:active_storage).try(:service)
+      #   puts obj.to_s # => "active_storage.service"
+      #
+      class TryMock
+        def initialize(array = [])
+          @try_array = array
+        end
+
+        def try(value)
+          @try_array << value
+          #{try_code}
+          return TryMock.new(@try_array)
+        end
+
+        def to_s
+          @try_array.join(".")
+        end
+      end
+
+      ARGV.shift           # remove "runner"
+      eval(ARGV.join(" ")) # Execute command passed in
+    FILE
+    FileUtils.mkdir("bin")
+    File.open("bin/rails", "w") { |f| f << executable_contents }
+    File.chmod(0o777, "bin/rails")
+  end
+end
diff --git a/spec/helpers/rake_runner_spec.rb b/spec/helpers/rake_runner_spec.rb
index deecb1ddf..086d696d5 100644
--- a/spec/helpers/rake_runner_spec.rb
+++ b/spec/helpers/rake_runner_spec.rb
@@ -1,50 +1,50 @@
-require 'spec_helper'
+require "spec_helper"
 
 describe "Rake Runner" do
   it "runs rake tasks that exist" do
-    Hatchet::App.new('asset_precompile_pass').in_directory do
+    Hatchet::App.new("asset_precompile_pass").in_directory_fork do
       rake = LanguagePack::Helpers::RakeRunner.new.load_rake_tasks!
       task = rake.task("assets:precompile")
       task.invoke
 
-      expect(task.status).to   eq(:pass)
-      expect(task.output).to   match("success!")
+      expect(task.output).to match("success!")
+      expect(task.status).to eq(:pass)
       expect(task.time).not_to be_nil
     end
   end
 
   it "detects when rake tasks fail" do
-    Hatchet::App.new('asset_precompile_fail').in_directory do
+    Hatchet::App.new("asset_precompile_fail").in_directory_fork do
       rake = LanguagePack::Helpers::RakeRunner.new.load_rake_tasks!
       task = rake.task("assets:precompile")
       task.invoke
 
-      expect(task.status).to   eq(:fail)
-      expect(task.output).to   match("assets:precompile fails")
+      expect(task.output).to match("assets:precompile fails")
+      expect(task.status).to eq(:fail)
       expect(task.time).not_to be_nil
     end
   end
 
   it "can show errors from bad Rakefiles" do
-    Hatchet::App.new('bad_rakefile').in_directory do
+    Hatchet::App.new("bad_rakefile").in_directory_fork do
       rake = LanguagePack::Helpers::RakeRunner.new.load_rake_tasks!
       task = rake.task("assets:precompile")
-      expect(rake.rakefile_can_load?).to be_false
-      expect(task.task_defined?).to      be_false
+      expect(rake.rakefile_can_load?).to be_falsey
+      expect(task.task_defined?).to be_falsey
     end
   end
 
   it "detects if task is missing" do
-    Hatchet::App.new('asset_precompile_not_found').in_directory do
+    Hatchet::App.new("asset_precompile_not_found").in_directory_fork do
       task = LanguagePack::Helpers::RakeRunner.new.task("assets:precompile")
-      expect(task.task_defined?).to be_false
+      expect(task.task_defined?).to be_falsey
     end
   end
 
   it "detects when no rakefile is present" do
-    Hatchet::App.new('no_rakefile').in_directory do
+    Hatchet::App.new("no_rakefile").in_directory_fork do
       runner = LanguagePack::Helpers::RakeRunner.new
-      expect(runner.rakefile_can_load?).to be_false
+      expect(runner.rakefile_can_load?).to be_falsey
     end
   end
 end
diff --git a/spec/helpers/ruby_version_spec.rb b/spec/helpers/ruby_version_spec.rb
index 46b429f41..6f6f2f94e 100644
--- a/spec/helpers/ruby_version_spec.rb
+++ b/spec/helpers/ruby_version_spec.rb
@@ -1,85 +1,295 @@
-require 'spec_helper'
+require "spec_helper"
 
 describe "RubyVersion" do
-  before(:each) do
-    @bundler = LanguagePack::Helpers::BundlerWrapper.new
-  end
+  it "knows the next logical version" do
+    version_number = "2.5.0"
+    ruby_version = LanguagePack::RubyVersion.default(last_version: version_number)
+    version = "ruby-#{version_number}"
 
-  after(:each) do
-    @bundler.clean
-  end
+    expect(ruby_version.version_for_download).to eq(version)
+    expect(ruby_version.next_logical_version).to eq("ruby-2.5.1")
+    expect(ruby_version.next_logical_version).to eq("ruby-2.5.1")
+    expect(ruby_version.next_logical_version(2)).to eq("ruby-2.5.2")
+    expect(ruby_version.next_logical_version(20)).to eq("ruby-2.5.20")
+    expect(ruby_version.bundler_directory).to eq("vendor/bundle/ruby/2.5.0")
 
-  it "correctly sets ruby version for bundler specified versions" do
-    Hatchet::App.new("mri_193").in_directory do |dir|
-      ruby_version   = LanguagePack::RubyVersion.new(@bundler.install, is_new: true)
-      version_number = "1.9.3"
-      version        = "ruby-#{version_number}"
-      expect(ruby_version.version_without_patchlevel).to eq(version)
-      expect(ruby_version.engine_version).to eq(version_number)
-      expect(ruby_version.to_gemfile).to eq("ruby '#{version_number}'")
-      expect(ruby_version.engine).to eq(:ruby)
-    end
+    # Minor version
+    expect(ruby_version.next_minor_version).to eq("ruby-2.6.0")
+    expect(ruby_version.next_minor_version(2)).to eq("ruby-2.7.0")
+
+    # Major Version
+    expect(ruby_version.next_major_version).to eq("ruby-3.0.0")
+    expect(ruby_version.next_major_version(2)).to eq("ruby-4.0.0")
   end
 
   it "correctly sets default ruby versions" do
-    Hatchet::App.new("default_ruby").in_directory do |dir|
-      ruby_version   = LanguagePack::RubyVersion.new(@bundler.install, is_new: true)
+    Hatchet::App.new("default_ruby").in_directory_fork do |_dir|
+      dir = Pathname(Dir.pwd)
+      ruby_version = LanguagePack::RubyVersion.from_gemfile_lock(
+        ruby: LanguagePack::Helpers::GemfileLock.new(
+          contents: dir.join("Gemfile.lock").read
+        ).ruby
+      )
+      version = LanguagePack::RubyVersion::DEFAULT_VERSION
       version_number = LanguagePack::RubyVersion::DEFAULT_VERSION_NUMBER
-      version        = LanguagePack::RubyVersion::DEFAULT_VERSION
-      expect(ruby_version.version_without_patchlevel).to eq(version)
+      major, minor, _ = version_number.split(".")
+      expect(ruby_version.version_for_download).to eq(version)
       expect(ruby_version.engine_version).to eq(version_number)
       expect(ruby_version.to_gemfile).to eq("ruby '#{version_number}'")
       expect(ruby_version.engine).to eq(:ruby)
       expect(ruby_version.default?).to eq(true)
+      expect(ruby_version.bundler_directory).to eq("vendor/bundle/ruby/#{major}.#{minor}.0")
     end
   end
 
-  it "correctly sets default legacy version" do
-    Hatchet::App.new("default_ruby").in_directory do |dir|
-      ruby_version   = LanguagePack::RubyVersion.new(@bundler.install, is_new: false)
-      version_number = LanguagePack::RubyVersion::LEGACY_VERSION_NUMBER
-      version        = LanguagePack::RubyVersion::LEGACY_VERSION
-      expect(ruby_version.version_without_patchlevel).to eq(version)
+  it "detects Ruby from Gemfile.lock" do
+    Hatchet::App.new("default_ruby").in_directory_fork do |_|
+      dir = Pathname(Dir.pwd)
+      dir.join("Gemfile.lock").write(<<~EOF)
+        GEM
+          remote: https://rubygems.org/
+          specs:
+            rake (13.2.1)
+
+        PLATFORMS
+          arm64-darwin-22
+          ruby
+          x86_64-linux
+
+        DEPENDENCIES
+          rake
+
+        RUBY VERSION
+           ruby 3.2.3p157
+
+        BUNDLED WITH
+           2.4.19
+      EOF
+
+      version_number = "3.2.3"
+      version = "ruby-#{version_number}"
+      ruby_version = LanguagePack::RubyVersion.from_gemfile_lock(
+        ruby: LanguagePack::Helpers::GemfileLock.new(
+          contents: dir.join("Gemfile.lock").read
+        ).ruby
+      )
+      expect(ruby_version.version_for_download).to eq(version)
       expect(ruby_version.engine_version).to eq(version_number)
-      expect(ruby_version.to_gemfile).to eq("ruby '#{version_number}'")
       expect(ruby_version.engine).to eq(:ruby)
     end
   end
 
-  it "detects Ruby 2.0.0" do
-    Hatchet::App.new("mri_200").in_directory do |dir|
-      ruby_version   = LanguagePack::RubyVersion.new(@bundler.install, is_new: true)
-      version_number = "2.0.0"
-      version        = "ruby-#{version_number}"
-      expect(ruby_version.version_without_patchlevel).to eq(version)
+  it "detects RC Ruby from Gemfile.lock" do
+    Hatchet::App.new("default_ruby").in_directory_fork do |_|
+      dir = Pathname(Dir.pwd)
+      dir.join("Gemfile.lock").write(<<~EOF)
+        GEM
+          remote: https://rubygems.org/
+          specs:
+            rake (13.2.1)
+
+        PLATFORMS
+          arm64-darwin-22
+          ruby
+          x86_64-linux
+
+        DEPENDENCIES
+          rake
+
+        RUBY VERSION
+           ruby 3.2.3.rc1
+
+        BUNDLED WITH
+           2.4.19
+      EOF
+
+      version_number = "3.2.3"
+      version = "ruby-#{version_number}.rc1"
+
+      # Shadow logic validation
+      ruby_version = LanguagePack::RubyVersion.from_gemfile_lock(
+        ruby: LanguagePack::Helpers::GemfileLock.new(
+          contents: dir.join("Gemfile.lock").read
+        ).ruby
+      )
+      expect(ruby_version.version_for_download).to eq(version)
       expect(ruby_version.engine_version).to eq(version_number)
-      expect(ruby_version.to_gemfile).to eq("ruby '#{version_number}'")
       expect(ruby_version.engine).to eq(:ruby)
     end
   end
 
+  it "detects pre versions that do not end in numbers" do
+    Hatchet::App.new("default_ruby").in_directory_fork do |_|
+      dir = Pathname(Dir.pwd)
+      dir.join("Gemfile.lock").write(<<~EOF)
+        GEM
+          remote: https://rubygems.org/
+          specs:
+            rake (13.2.1)
+
+        PLATFORMS
+          arm64-darwin-22
+          ruby
+          x86_64-linux
+
+        DEPENDENCIES
+          rake
+
+        RUBY VERSION
+           ruby 3.2.3.lol
+
+        BUNDLED WITH
+           2.4.19
+      EOF
+
+      version_number = "3.2.3"
+      version = "ruby-#{version_number}.lol"
+
+      ruby_version = LanguagePack::RubyVersion.from_gemfile_lock(
+        ruby: LanguagePack::Helpers::GemfileLock.new(
+          contents: dir.join("Gemfile.lock").read
+        ).ruby
+      )
+      expect(ruby_version.version_for_download).to eq(version)
+      expect(ruby_version.engine_version).to eq(version_number)
+      expect(ruby_version.engine).to eq(:ruby)
+      expect(ruby_version.bundler_directory).to eq("vendor/bundle/ruby/3.2.0")
+    end
+  end
 
   it "detects non mri engines" do
-    Hatchet::App.new("ruby_193_jruby_173").in_directory do |dir|
-      ruby_version   = LanguagePack::RubyVersion.new(@bundler.install, is_new: true)
-      version_number = "1.9.3"
-      engine_version = "1.7.3"
-      engine         = :jruby
-      version        = "ruby-#{version_number}-#{engine}-#{engine_version}"
-      to_gemfile     = "ruby '#{version_number}', :engine => '#{engine}', :engine_version => '#{engine_version}'"
-      expect(ruby_version.version_without_patchlevel).to eq(version)
+    Hatchet::App.new("default_ruby").in_directory_fork do |_|
+      dir = Pathname(Dir.pwd)
+      dir.join("Gemfile.lock").write(<<~EOF)
+        GEM
+          remote: https://rubygems.org/
+          specs:
+        PLATFORMS
+          java
+
+        DEPENDENCIES
+
+        RUBY VERSION
+           ruby 2.6.8p001 (jruby 9.3.6.0)
+
+        BUNDLED WITH
+           2.3.25
+      EOF
+
+      version_number = "2.6.8"
+      engine_version = "9.3.6.0"
+      engine = :jruby
+
+      ruby_version = LanguagePack::RubyVersion.from_gemfile_lock(
+        ruby: LanguagePack::Helpers::GemfileLock.new(
+          contents: dir.join("Gemfile.lock").read
+        ).ruby
+      )
+      expect(ruby_version.version_for_download).to eq("ruby-#{version_number}-#{engine}-#{engine_version}")
       expect(ruby_version.engine_version).to eq(engine_version)
-      expect(ruby_version.to_gemfile).to eq(to_gemfile)
       expect(ruby_version.engine).to eq(engine)
+      expect(ruby_version.bundler_directory).to eq("vendor/bundle/jruby/2.6.0")
     end
   end
+end
+
+describe "get_ruby_version .ruby-version comparison" do
+  def gemfile_lock_with_ruby(version)
+    LanguagePack::Helpers::GemfileLock.new(
+      report: HerokuBuildReport.dev_null,
+      contents: <<~EOF
+        RUBY VERSION
+           ruby #{version}
+        BUNDLED WITH
+           2.5.23
+      EOF
+    )
+  end
 
-  it "surfaces error message from bundler"  do
-    bundle_error_msg = "Zomg der was a problem in da gemfile"
-    error_klass      = LanguagePack::Helpers::BundlerWrapper::GemfileParseError
-    Hatchet::App.new("bad_gemfile_on_platform").in_directory do |dir|
-      @bundler       = LanguagePack::Helpers::BundlerWrapper.new()
-      expect {LanguagePack::RubyVersion.new(@bundler)}.to raise_error(error_klass, /#{Regexp.escape(bundle_error_msg)}/)
+  def gemfile_lock_default
+    LanguagePack::Helpers::GemfileLock.new(
+      report: HerokuBuildReport.dev_null,
+      contents: <<~EOF
+        BUNDLED WITH
+           2.5.23
+      EOF
+    )
+  end
+
+  def dot_ruby_version_result(version)
+    LanguagePack::Helpers::DotRubyVersionFile.new(contents: version).call
+  end
+
+  def get_ruby_version(gemfile_lock:, dot_ruby_version_result: nil)
+    report = HerokuBuildReport.dev_null
+    Dir.mktmpdir do |dir|
+      metadata = LanguagePack::Metadata.new(cache_path: dir)
+      LanguagePack::Ruby.get_ruby_version(
+        metadata: metadata,
+        gemfile_lock: gemfile_lock,
+        dot_ruby_version_result: dot_ruby_version_result,
+        report: report
+      )
     end
+    report
+  end
+
+  it "sets no comparison keys when .ruby-version is absent" do
+    report = get_ruby_version(gemfile_lock: gemfile_lock_with_ruby("3.4.2"))
+
+    expect(report.data).not_to have_key("dot_ruby_version.version")
+    expect(report.data).not_to have_key("dot_ruby_version.vs_gemfile_lock")
+  end
+
+  it "sets no comparison keys when .ruby-version is unparseable" do
+    result = dot_ruby_version_result("not-a-version")
+    report = get_ruby_version(
+      gemfile_lock: gemfile_lock_with_ruby("3.4.2"),
+      dot_ruby_version_result: result
+    )
+
+    expect(result.ruby_version).to be_nil
+    expect(report.data).not_to have_key("dot_ruby_version.version")
+    expect(report.data).not_to have_key("dot_ruby_version.vs_gemfile_lock")
+  end
+
+  it "reports match when versions are equal" do
+    report = get_ruby_version(
+      gemfile_lock: gemfile_lock_with_ruby("3.4.2"),
+      dot_ruby_version_result: dot_ruby_version_result("3.4.2")
+    )
+
+    expect(report.data["dot_ruby_version.version"]).to eq("3.4.2")
+    expect(report.data["dot_ruby_version.vs_gemfile_lock"]).to eq("match")
+  end
+
+  it "reports dot_ruby_version_higher when .ruby-version is newer" do
+    report = get_ruby_version(
+      gemfile_lock: gemfile_lock_with_ruby("3.4.2"),
+      dot_ruby_version_result: dot_ruby_version_result("3.5.0")
+    )
+
+    expect(report.data["dot_ruby_version.version"]).to eq("3.5.0")
+    expect(report.data["dot_ruby_version.vs_gemfile_lock"]).to eq("dot_ruby_version_higher")
+  end
+
+  it "reports gemfile_lock_higher when Gemfile.lock is newer" do
+    report = get_ruby_version(
+      gemfile_lock: gemfile_lock_with_ruby("3.4.2"),
+      dot_ruby_version_result: dot_ruby_version_result("3.3.0")
+    )
+
+    expect(report.data["dot_ruby_version.version"]).to eq("3.3.0")
+    expect(report.data["dot_ruby_version.vs_gemfile_lock"]).to eq("gemfile_lock_higher")
+  end
+
+  it "sets version but skips comparison when Gemfile.lock has no ruby version" do
+    report = get_ruby_version(
+      gemfile_lock: gemfile_lock_default,
+      dot_ruby_version_result: dot_ruby_version_result("3.4.2")
+    )
+
+    expect(report.data["dot_ruby_version.version"]).to eq("3.4.2")
+    expect(report.data).not_to have_key("dot_ruby_version.vs_gemfile_lock")
   end
 end
diff --git a/spec/helpers/shell_spec.rb b/spec/helpers/shell_spec.rb
index 3f1591d97..93a12b537 100644
--- a/spec/helpers/shell_spec.rb
+++ b/spec/helpers/shell_spec.rb
@@ -1,23 +1,83 @@
-require 'spec_helper'
+require "spec_helper"
 
+describe "ShellHelpers" do
+  module RecordPuts # standard:disable Lint/ConstantDefinitionInBlock
+    attr_reader :puts_calls, :print_calls
+    def puts(*args)
+      @puts_calls ||= []
+      @puts_calls << args
+    end
 
-class FakeShell
-  include LanguagePack::ShellHelpers
-end
+    def print(*args)
+      @print_calls ||= []
+      @print_calls << args
+    end
+  end
+
+  class FakeShell # standard:disable Lint/ConstantDefinitionInBlock
+    include RecordPuts
+    include LanguagePack::ShellHelpers
+  end
+
+  describe "pipe" do
+    it "does not double append newlines" do
+      sh = FakeShell.new
+      sh.pipe("bundle install")
+      first_line = sh.print_calls.first.first
+      expect(first_line.end_with?("\n\n")).to be(false)
+    end
+  end
 
+  describe "#command_options_to_string" do
+    it "formats ugly keys correctly" do
+      env = {%( un"matched ) => "bad key"}
+      result = FakeShell.new.command_options_to_string("bundle install", env: env)
+      expected = %r{env \\ un\\"matched\\ =bad\\ key bash -c bundle\\ install 2>&1}
+      expect(result.strip).to match(expected)
+    end
 
-describe "ShellHelpers" do
-  it "format ugly keys correctly" do
-    env      = {%Q{ un"matched } => "bad key"}
-    result   = FakeShell.new.command_options_to_string("bundle install", env:  env)
-    expected = %r{env \\ un\\\"matched\\ =bad\\ key bash -c bundle\\ install 2>&1}
-    expect(result.strip).to match(expected)
+    it "formats ugly values correctly" do
+      env = {"BAD VALUE" => %{ )(*&^%$#'$'\n''@!~' }}
+      result = FakeShell.new.command_options_to_string("bundle install", env: env)
+      expected = %r{env BAD\\ VALUE=\\ \\\)\\\(\\\*\\&\\\^\\%\\\$\\#\\'\\\$\\''\n'\\'\\'@\\!\\~\\'\\  bash -c bundle\\ install 2>&1}
+      expect(result.strip).to match(expected)
+    end
   end
 
-  it "formats ugly values correctly" do
-    env      = {"BAD VALUE"      => %Q{ )(*&^%$#'$'\n''@!~\'\ }}
-    result   = FakeShell.new.command_options_to_string("bundle install", env:  env)
-    expected = %r{env BAD\\ VALUE=\\ \\\)\\\(\\\*\\&\\\^\\%\\\$\\#\\'\\\$\\''\n'\\'\\'@\\!\\~\\'\\  bash -c bundle\\ install 2>&1}
-    expect(result.strip).to match(expected)
+  describe "#run!" do
+    it "retries failed commands when passed max_attempts: > 1" do
+      sh = FakeShell.new
+      expect { sh.run!("false", max_attempts: 3) }.to raise_error(StandardError)
+
+      expect(sh.print_calls).to eq([
+        ["       Command: 'false' failed on attempt 1 of 3.\n"],
+        ["       Command: 'false' failed on attempt 2 of 3.\n"]
+      ])
+    end
+  end
+
+  describe "#puts" do
+    context "when the message has an invalid utf-8 character" do
+      it "no error is raised by puts directly" do
+        sh = FakeShell.new
+
+        bad_lines = File.read("spec/fixtures/invalid_encoding.log")
+        sh.puts(bad_lines)
+      end
+
+      it "from an internal call, it catches and annotates it" do
+        sh = FakeShell.new
+
+        def sh.print(string)
+          # Strip emits a UTF-8 error
+          string.strip
+        end
+
+        bad_lines = File.read("spec/fixtures/invalid_encoding.log")
+        expect { sh.puts(bad_lines) }.to raise_error do |error|
+          expect(error.message).to include("Invalid string:")
+        end
+      end
+    end
   end
 end
diff --git a/spec/helpers/stale_file_cleaner_spec.rb b/spec/helpers/stale_file_cleaner_spec.rb
index 52fef9632..58f0cd5cb 100644
--- a/spec/helpers/stale_file_cleaner_spec.rb
+++ b/spec/helpers/stale_file_cleaner_spec.rb
@@ -1,7 +1,6 @@
-require 'spec_helper'
+require "spec_helper"
 
 describe "Cleans Stale Files" do
-
   it "removes files if they go over the limit" do
     file_size = 1000
     Dir.mktmpdir do |dir|
@@ -9,13 +8,13 @@
       sleep 1 # need mtime of files to be different
       new_file = create_file_with_size_in(file_size, dir)
 
-      expect(old_file.exist?).to be_true
-      expect(new_file.exist?).to be_true
+      expect(old_file.exist?).to be_truthy
+      expect(new_file.exist?).to be_truthy
 
-      ::LanguagePack::Helpers::StaleFileCleaner.new(dir).clean_over(2*file_size - 50)
+      ::LanguagePack::Helpers::StaleFileCleaner.new(dir).clean_over(2 * file_size - 50)
 
-      expect(old_file.exist?).to be_false
-      expect(new_file.exist?).to be_true
+      expect(old_file.exist?).to be_falsey
+      expect(new_file.exist?).to be_truthy
     end
   end
 
@@ -26,14 +25,14 @@
       sleep 1 # need mtime of files to be different
       new_file = create_file_with_size_in(file_size, dir)
 
-      expect(old_file.exist?).to be_true
-      expect(new_file.exist?).to be_true
-      dir_size = File.stat(dir)
+      expect(old_file.exist?).to be_truthy
+      expect(new_file.exist?).to be_truthy
+      File.stat(dir)
 
-      ::LanguagePack::Helpers::StaleFileCleaner.new(dir).clean_over(2*file_size + 50)
+      ::LanguagePack::Helpers::StaleFileCleaner.new(dir).clean_over(2 * file_size + 50)
 
-      expect(old_file.exist?).to be_true
-      expect(new_file.exist?).to be_true
+      expect(old_file.exist?).to be_truthy
+      expect(new_file.exist?).to be_truthy
     end
   end
 end
diff --git a/spec/helpers/yarn_installer_spec.rb b/spec/helpers/yarn_installer_spec.rb
new file mode 100644
index 000000000..72ababca7
--- /dev/null
+++ b/spec/helpers/yarn_installer_spec.rb
@@ -0,0 +1,18 @@
+require "spec_helper"
+
+describe LanguagePack::Helpers::YarnInstaller do
+  describe "#install" do
+    it "should extract the yarn package" do
+      Dir.mktmpdir do |dir|
+        Dir.chdir(dir) do
+          installer = LanguagePack::Helpers::YarnInstaller.new
+          installer.install
+
+          # webpacker gem checks for yarnpkg
+          # https://github.com/rails/webpacker/blob/master/lib/install/bin/yarn.tt#L5
+          expect(File.exist?("yarn-v#{installer.version}/bin/yarnpkg")).to be(true)
+        end
+      end
+    end
+  end
+end
diff --git a/spec/no_lockfile_spec.rb b/spec/no_lockfile_spec.rb
deleted file mode 100644
index e3d121f54..000000000
--- a/spec/no_lockfile_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require 'spec_helper'
-
-describe "No Lockfile" do
-  it "should not deploy" do
-    Hatchet::Runner.new("no_lockfile", allow_failure: true).deploy do |app|
-      expect(app).not_to be_deployed
-      expect(app.output).to include("Gemfile.lock required")
-    end
-  end
-end
diff --git a/spec/rails23_spec.rb b/spec/rails23_spec.rb
deleted file mode 100644
index a09f0284b..000000000
--- a/spec/rails23_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require_relative 'spec_helper'
-
-describe "Rails 2.3.x" do
-  it "should deploy on ruby 1.8.7" do
-    Hatchet::Runner.new("rails23_mri_187").deploy do |app, heroku|
-      add_database(app, heroku)
-      expect(successful_body(app)).to eq("hello")
-    end
-  end
-end
diff --git a/spec/rails3_spec.rb b/spec/rails3_spec.rb
deleted file mode 100644
index 6b5fe9c6b..000000000
--- a/spec/rails3_spec.rb
+++ /dev/null
@@ -1,55 +0,0 @@
-require_relative 'spec_helper'
-
-describe "Rails 3.x" do
-  it "should deploy on ruby 1.9.3" do
-    Hatchet::Runner.new("rails3_mri_193").deploy do |app, heroku|
-      expect(app.output).to include("Asset precompilation completed")
-      add_database(app, heroku)
-
-      expect(app.output).to match("WARNINGS")
-      expect(app.output).to match("Add 'rails_12factor' gem to your Gemfile to skip plugin injection")
-
-      ls = app.run("ls vendor/plugins")
-      expect(ls).to match("rails3_serve_static_assets")
-      expect(ls).to match("rails_log_stdout")
-
-      expect(successful_body(app)).to eq("hello")
-    end
-  end
-
-  it "should not have warnings when using the rails_12factor gem" do
-    Hatchet::Runner.new("rails3_12factor").deploy do |app, heroku|
-      add_database(app, heroku)
-      expect(app.output).not_to match("Add 'rails_12factor' gem to your Gemfile to skip plugin injection")
-      expect(successful_body(app)).to eq("hello")
-    end
-  end
-
-  it "should only display the correct plugin warning" do
-    Hatchet::Runner.new("rails3_one_plugin").deploy do |app, heroku|
-      add_database(app, heroku)
-      expect(app.output).not_to match("rails_log_stdout")
-      expect(app.output).to match("rails3_serve_static_assets")
-      expect(app.output).to match("Add 'rails_12factor' gem to your Gemfile to skip plugin injection")
-      expect(successful_body(app)).to eq("hello")
-    end
-  end
-
-  context "when not using the rails gem" do
-    it "should deploy on ruby 1.9.3" do
-      Hatchet::Runner.new("railties3_mri_193").deploy do |app, heroku|
-        expect(app.output).to include("Asset precompilation completed")
-        add_database(app, heroku)
-        expect(app.output).to match("Ruby/Rails")
-        expect(successful_body(app)).to eq("hello")
-      end
-    end
-  end
-
-  it "fails compile if assets:precompile fails" do
-    Hatchet::Runner.new("rails3-fail-assets-compile", allow_failure: true).deploy do |app, heroku|
-      expect(app.output).to include("raising on assets:precompile on purpose")
-      expect(app).not_to be_deployed
-    end
-  end
-end
diff --git a/spec/rails41_spec.rb b/spec/rails41_spec.rb
deleted file mode 100644
index ca43052ab..000000000
--- a/spec/rails41_spec.rb
+++ /dev/null
@@ -1,29 +0,0 @@
-require_relative 'spec_helper'
-
-describe "Rails 4.1.x" do
-  it "should detect rails successfully" do
-    Hatchet::App.new('rails41_scaffold').in_directory do
-      expect(LanguagePack::Rails41.use?).to eq(true)
-    end
-    Hatchet::App.new('rails41_scaffold').in_directory do
-      expect(LanguagePack::Rails4.use?).to eq(false)
-    end
-  end
-
-  it "should be able to run a migration without heroku specific database.yml" do
-    Hatchet::Runner.new("rails41_scaffold").deploy do |app, heroku|
-      add_database(app, heroku)
-      expect(app.output).not_to include("Writing config/database.yml to read from DATABASE_URL")
-      expect(app.run("rake db:migrate")).to include("20140218165801 CreatePeople")
-    end
-  end
-
-  it "should handle secrets.yml properly" do
-    Hatchet::Runner.new("rails41_scaffold").deploy do |app, heroku|
-      add_database(app, heroku)
-      ReplRunner.new(:rails_console, "heroku run bin/rails console -a #{app.name}").run do |console|
-        console.run("ENV['SECRET_KEY_BASE'] == Rails.application.config.secrets.secret_key_base") {|result| expect(result).not_to eq("true") }
-      end
-    end
-  end
-end
diff --git a/spec/rails4_spec.rb b/spec/rails4_spec.rb
deleted file mode 100644
index d9372cacd..000000000
--- a/spec/rails4_spec.rb
+++ /dev/null
@@ -1,57 +0,0 @@
-require_relative 'spec_helper'
-
-describe "Rails 4.0.x" do
-  it "should detect rails successfully" do
-    Hatchet::App.new('rails4-manifest').in_directory do
-      expect(LanguagePack::Rails4.use?).to eq(true)
-    end
-    Hatchet::App.new('rails4-manifest').in_directory do
-      expect(LanguagePack::Rails3.use?).to eq(false)
-    end
-  end
-
-  it "should deploy on ruby 2.0.0" do
-    Hatchet::Runner.new("rails4-manifest").deploy do |app, heroku|
-      add_database(app, heroku)
-      expect(app.output).to include("Detected manifest file, assuming assets were compiled locally")
-      expect(app.output).not_to match("Include 'rails_12factor' gem to enable all platform features")
-    end
-  end
-
-  it "upgraded from 3 to 4 missing ./bin still works" do
-    Hatchet::Runner.new("rails3-to-4-no-bin").deploy do |app, heroku|
-      expect(app.output).to include("Asset precompilation completed")
-      add_database(app, heroku)
-
-      expect(app.output).to match("WARNINGS")
-      expect(app.output).to match("Include 'rails_12factor' gem to enable all platform features")
-
-      app.run("rails console") do |console|
-        console.run("'hello' + 'world'") {|result| expect(result).to match('helloworld')}
-      end
-    end
-  end
-
-  it "works with windows" do
-    Hatchet::Runner.new("rails4_windows_mri193").deploy do |app, heroku|
-      result = app.run("rails -v")
-      expect(result).to match("4.0.0")
-
-      result = app.run("rake -T")
-      expect(result).to match("assets:precompile")
-
-      result = app.run("bundle show rails")
-      expect(result).to match("rails-4.0.0")
-
-      before_warnings = app.output.split("WARNINGS:").first
-      expect(before_warnings).to match("Removing `Gemfile.lock`")
-    end
-  end
-
-  it "fails compile if assets:precompile fails" do
-    Hatchet::Runner.new("rails4-fail-assets-compile", allow_failure: true).deploy do |app, heroku|
-      expect(app.output).to include("raising on assets:precompile on purpose")
-      expect(app).not_to be_deployed
-    end
-  end
-end
diff --git a/spec/rake/deploy_check_spec.rb b/spec/rake/deploy_check_spec.rb
new file mode 100644
index 000000000..a755fe3b2
--- /dev/null
+++ b/spec/rake/deploy_check_spec.rb
@@ -0,0 +1,170 @@
+require "spec_helper"
+require "rake/deploy_check"
+
+describe "A helper class for deploying" do
+  describe "tests that hit github" do
+    it "know remote tags" do
+      Dir.mktmpdir do |dir|
+        Dir.chdir(dir) do
+          run!("touch foo; git init; git add .; git commit -m first")
+
+          deploy = DeployCheck.new(github: "heroku/heroku-buildpack-ruby")
+          expect(deploy.remote_tag_array.class).to eq(Array)
+          expect(deploy.remote_tag_array).to include("v218")
+
+          expect(deploy.remote_tag_matches?(local_sha: "nope")).to be_falsey
+          expect(deploy.remote_tag_matches?(remote_sha: "nope")).to be_falsey
+        end
+      end
+    end
+
+    it "remote sha" do
+      deploy = DeployCheck.new(github: "sharpstone/do_not_delete_or_modify")
+      expect(deploy.remote_commit_sha).to eq("3a9ff6433a05560acfd06dda03a11605a96ae133")
+    end
+
+    it "local_commit_sha" do
+      Dir.mktmpdir do |dir|
+        Dir.chdir(dir) do
+          run!("git clone https://github.com/sharpstone/default_ruby #{dir} 2>&1 && cd #{dir} && git checkout 6e642963acec0ff64af51bd6fba8db3c4176ed6e 2>&1 && git checkout -b mybranch 2>&1")
+          deploy = DeployCheck.new(github: "heroku/heroku-buildpack-ruby")
+          expect(deploy.local_commit_sha).to eq("6e642963acec0ff64af51bd6fba8db3c4176ed6e")
+        end
+      end
+    end
+  end
+
+  describe "tests that do NOT hit github" do
+    it "checks multiple things" do
+      deploy = DeployCheck.new(github: "heroku/heroku-buildpack-ruby")
+      deploy.instance_variable_set(:@methods_called, [])
+
+      def deploy.check_version!
+        @methods_called << :check_version!
+      end
+
+      def deploy.check_unstaged!
+        @methods_called << :check_unstaged!
+      end
+
+      def deploy.check_branch!
+        @methods_called << :check_branch!
+      end
+
+      def deploy.check_changelog!
+        @methods_called << :check_changelog!
+      end
+
+      def deploy.check_sync!
+        @methods_called << :check_sync!
+      end
+
+      deploy.check!
+
+      methods_called = deploy.instance_variable_get(:@methods_called)
+      expect(methods_called).to include(:check_version!)
+      expect(methods_called).to include(:check_unstaged!)
+      expect(methods_called).to include(:check_branch!)
+      expect(methods_called).to include(:check_changelog!)
+      expect(methods_called).to include(:check_sync!)
+    end
+
+    it "checks version" do
+      ["v123abc", "123", "V123"].each do |bad_version|
+        deploy = DeployCheck.new(github: "heroku/heroku-buildpack-ruby", next_version: bad_version)
+        expect {
+          deploy.check_version!
+        }.to raise_error(/Must look like a version/)
+      end
+    end
+
+    it "checks local sha and remote sha match" do
+      deploy = DeployCheck.new(github: "heroku/heroku-buildpack-ruby")
+      expect {
+        deploy.check_sync!(local_sha: "a", remote_sha: "not a")
+      }.to raise_error(/Must be in-sync/)
+
+      deploy = DeployCheck.new(github: "heroku/heroku-buildpack-ruby")
+      deploy.check_sync!(
+        local_sha: "cbe100933b1e50953f0da35aafc50374ae2a31f9",
+        remote_sha: "cbe100933b1e50953f0da35aafc50374ae2a31f9"
+      )
+    end
+
+    it "github url" do
+      deploy = DeployCheck.new(github: "heroku/heroku-buildpack-ruby")
+      expect(deploy.github_url).to eq("https://github.com/heroku/heroku-buildpack-ruby")
+    end
+
+    it "knows the next version" do
+      deploy = DeployCheck.new(github: "heroku/heroku-buildpack-ruby", next_version: "v123")
+
+      def deploy.remote_tag_array
+        ["v123"]
+      end
+
+      expect(deploy.tag_exists_on_remote?).to be_truthy
+
+      deploy = DeployCheck.new(github: "heroku/heroku-buildpack-ruby", next_version: "v124")
+
+      def deploy.remote_tag_array
+        ["v123"]
+      end
+
+      expect(deploy.tag_exists_on_remote?).to be_falsey
+    end
+
+    it "checks remote tags for existance" do
+      deploy = DeployCheck.new(github: "heroku/heroku-buildpack-ruby")
+
+      def deploy.remote_tag_array
+        ["v123"]
+      end
+
+      expect(deploy.next_version).to eq("v124")
+    end
+
+    it "checks unstaged" do
+      Dir.mktmpdir do |dir|
+        Dir.chdir(dir) do
+          deploy = DeployCheck.new(github: "heroku/heroku-buildpack-ruby")
+          run!("echo 'blerg' >> foo.txt")
+          run!("git init .; git add . ; git commit -m first")
+          deploy.check_unstaged!
+
+          run!("echo 'foo' >> foo.txt")
+          expect { deploy.check_unstaged! }.to raise_error(/Must have all changes committed/)
+        end
+      end
+    end
+
+    it "checks branch" do
+      Dir.mktmpdir do |dir|
+        Dir.chdir(dir) do
+          deploy = DeployCheck.new(github: "heroku/heroku-buildpack-ruby")
+          run!("echo 'blerg' >> foo.txt")
+          run!("git init .; git add . ; git commit -m first")
+          run!("git checkout -B main")
+          deploy.check_branch!
+
+          expect { deploy.check_branch!("not_main") }.to raise_error(/Must be on main branch/)
+        end
+      end
+    end
+
+    it "checks CHANGELOG" do
+      Dir.mktmpdir do |dir|
+        Dir.chdir(dir) do
+          deploy = DeployCheck.new(github: "heroku/heroku-buildpack-ruby", next_version: "v999")
+          run!("touch CHANGELOG.md")
+          expect {
+            deploy.check_changelog!
+          }.to raise_error(/Expected CHANGELOG.md to include \[v999\]/)
+
+          run!("echo '## [v999]' >> CHANGELOG.md")
+          deploy.check_changelog!
+        end
+      end
+    end
+  end
+end
diff --git a/spec/rubies_spec.rb b/spec/rubies_spec.rb
deleted file mode 100644
index 9d61c33f5..000000000
--- a/spec/rubies_spec.rb
+++ /dev/null
@@ -1,61 +0,0 @@
-require_relative 'spec_helper'
-
-describe "Ruby Versions" do
-  it "should deploy ruby 1.8.7 properly" do
-    Hatchet::Runner.new("mri_187").deploy do |app|
-      version = '1.8.7'
-      expect(app.output).to match(version)
-      expect(app.run('ruby -v')).to match(version)
-    end
-  end
-
-  it "should deploy ruby 1.9.2 properly" do
-    Hatchet::Runner.new("mri_192").deploy do |app|
-      version = '1.9.2'
-      expect(app.output).to match(version)
-      expect(app.run('ruby -v')).to match(version)
-    end
-  end
-
-  it "should deploy ruby 1.9.2 properly (git)" do
-    Hatchet::GitApp.new("mri_192", buildpack: git_repo).deploy do |app|
-      version = '1.9.2'
-      expect(app.output).to match(version)
-      expect(app.run('ruby -v')).to match(version)
-    end
-  end
-
-  it "should deploy ruby 1.9.3 properly" do
-    Hatchet::Runner.new("mri_193").deploy do |app|
-      version = '1.9.3'
-      expect(app.output).to match(version)
-      expect(app.run('ruby -v')).to match(version)
-    end
-  end
-
-  it "should deploy ruby 2.0.0 properly" do
-    Hatchet::Runner.new("mri_200").deploy do |app|
-      version = '2.0.0'
-      expect(app.output).to match(version)
-      expect(app.run('ruby -v')).to match(version)
-    end
-  end
-
-  it "should deploy jruby 1.7.3 (legacy jdk) properly" do
-    Hatchet::AnvilApp.new("ruby_193_jruby_173").deploy do |app|
-      expect(app.output).to match("Installing JVM: openjdk1.7.0_25")
-      expect(app.output).to match("ruby-1.9.3-jruby-1.7.3")
-      expect(app.output).not_to include("OpenJDK 64-Bit Server VM warning")
-      expect(app.run('ruby -v')).to match("jruby 1.7.3")
-    end
-  end
-
-  it "should deploy jruby 1.7.6 (latest jdk) properly" do
-    Hatchet::AnvilApp.new("ruby_193_jruby_176").deploy do |app|
-      expect(app.output).to match("Installing JVM: openjdk7-latest")
-      expect(app.output).to match("ruby-1.9.3-jruby-1.7.6")
-      expect(app.output).not_to include("OpenJDK 64-Bit Server VM warning")
-      expect(app.run('ruby -v')).to match("jruby 1.7.6")
-    end
-  end
-end
diff --git a/spec/ruby_spec.rb b/spec/ruby_spec.rb
deleted file mode 100644
index d6216fe2c..000000000
--- a/spec/ruby_spec.rb
+++ /dev/null
@@ -1,33 +0,0 @@
-require_relative 'spec_helper'
-
-describe "Ruby apps" do
-  describe "Rake detection" do
-    context "Ruby 1.8.7" do
-      it "doesn't run rake tasks if no rake gem" do
-        Hatchet::Runner.new('mri_187_no_rake').deploy do |app, heroku|
-          expect(app.output).not_to include("foo")
-        end
-      end
-
-      it "runs a rake task if the gem exists" do
-        Hatchet::Runner.new('mri_187_rake').deploy do |app, heroku|
-          expect(app.output).to include("foo")
-        end
-      end
-    end
-
-    context "Ruby 1.9+" do
-      it "runs rake tasks if no rake gem" do
-        Hatchet::Runner.new('mri_200_no_rake').deploy do |app, heroku|
-          expect(app.output).to include("foo")
-        end
-      end
-
-      it "runs a rake task if the gem exists" do
-        Hatchet::Runner.new('mri_200_rake').deploy do |app, heroku|
-          expect(app.output).to include("foo")
-        end
-      end
-    end
-  end
-end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 2a64d3ff4..802052210 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,47 +1,198 @@
-require 'rspec/core'
-require 'hatchet'
-require 'fileutils'
-require 'hatchet'
-require 'rspec/retry'
-require 'language_pack'
+require "rspec/core"
+require "hatchet"
+require "fileutils"
+require "stringio"
+require "rspec/retry"
+require "language_pack"
+require "language_pack/shell_helpers"
 
-require 'language_pack'
+ENV["HATCHET_BUILDPACK_BASE"] ||= "https://github.com/heroku/heroku-buildpack-ruby"
 
-ENV['RACK_ENV'] = 'test'
+ENV["RACK_ENV"] = "test"
+
+DEFAULT_STACK = "heroku-24"
+
+def hatchet_path(path = "")
+  Pathname(__FILE__).join("../../repos").expand_path.join(path)
+end
 
 RSpec.configure do |config|
-  config.filter_run focused: true unless ENV['IS_RUNNING_ON_TRAVIS']
-  config.run_all_when_everything_filtered = true
   config.alias_example_to :fit, focused: true
-  config.full_backtrace      = true
-  config.verbose_retry       = true # show retry status in spec process
-  config.default_retry_count = 2 if ENV['IS_RUNNING_ON_TRAVIS'] # retry all tests that fail again
+  config.full_backtrace = true
+  config.verbose_retry = true # show retry status in spec process
+  config.example_status_persistence_file_path = "spec/examples.txt"
 
   config.expect_with :rspec do |c|
+    c.max_formatted_output_length = Float::INFINITY
     c.syntax = :expect
   end
-  config.mock_with :none
-end
-
-def git_repo
-  "https://github.com/heroku/heroku-buildpack-ruby.git"
-end
-
-def add_database(app, heroku)
-  Hatchet::RETRIES.times.retry do
-    heroku.post_addon(app.name, 'heroku-postgresql:hobby-dev')
-    _, value = heroku.get_config_vars(app.name).body.detect {|key, value| key.match(/HEROKU_POSTGRESQL_[A-Z]+_URL/) }
-    heroku.put_config_vars(app.name, 'DATABASE_URL' => value)
-  end
+  config.mock_with :nothing
+  config.include LanguagePack::ShellHelpers
 end
 
 def successful_body(app, options = {})
   retry_limit = options[:retry_limit] || 50
-  Excon.get("http://#{app.name}.herokuapp.com", :idempotent => true, :expects => 200, :retry_limit => retry_limit).body
+  url = "http://#{app.name}.herokuapp.com"
+  Excon.get(url, idempotent: true, expects: 200, retry_limit: retry_limit).body
 end
 
 def create_file_with_size_in(size, dir)
   name = File.join(dir, SecureRandom.hex(16))
-  File.open(name, 'w') {|f| f.print([ 1 ].pack("C") * size) }
+  File.open(name, "w") { |f| f.print([1].pack("C") * size) }
   Pathname.new name
 end
+
+def buildpack_path
+  File.expand_path(File.join("../.."), __FILE__)
+end
+
+def fixture_path(path)
+  Pathname.new(__FILE__).join("../fixtures").expand_path.join(path)
+end
+
+def set_lts_ruby_version
+  set_ruby_version(version: "3.3.6")
+end
+
+def set_ruby_version(version:)
+  # Last ruby declaration in the gemfile wins
+  Pathname("Gemfile").write("\nruby '#{version}'", mode: "a")
+
+  # Update the Gemfile.lock to match
+  contents = Pathname("Gemfile.lock").read.concat(<<~EOF)
+
+    RUBY VERSION
+       ruby #{version}p170
+  EOF
+  Pathname("Gemfile.lock").write(contents)
+end
+
+def set_bundler_version(version:)
+  gemfile_lock = Pathname("Gemfile.lock").read
+
+  version = if version == :default
+    ""
+  else
+    "BUNDLED WITH\n   #{version}"
+  end
+  gemfile_lock.gsub!(/^BUNDLED WITH$(?:\r?\n) {2,3}(?<major>\d+)\.(?<minor>\d+)\.\d+/m, version)
+  gemfile_lock << "\n#{version}" unless gemfile_lock.match?(/^BUNDLED WITH/)
+
+  Pathname("Gemfile.lock").write(gemfile_lock)
+end
+
+def rails_lts_config
+  {"BUNDLE_GEMS__RAILSLTS__COM" => ENV["RAILS_LTS_CREDS"]}
+end
+
+def rails_lts_stack
+  "heroku-22"
+end
+
+def dyno_status(app, ps_name = "web")
+  app
+    .api_rate_limit.call
+    .dyno
+    .list(app.name)
+    .detect { |x| x["type"] == ps_name }
+end
+
+def wait_for_dyno_boot(app, ps_name = "web", sleep_val = 1)
+  while ["starting", "restarting"].include?(dyno_status(app, ps_name)["state"])
+    sleep sleep_val
+  end
+  dyno_status(app, ps_name)
+end
+
+def web_boot_status(app)
+  wait_for_dyno_boot(app)["state"]
+end
+
+def root_dir
+  Pathname(__dir__).join("..")
+end
+
+# Helper class for capturing and comparing environment variables in test output
+# Used by both deploy tests and CI tests
+class EnvDiff
+  attr_reader :added, :modified, :path_before, :path_after, :env_hash
+
+  def initialize(output, build_dir_pattern: /BUILD_DIR: (.+)/)
+    if build_dir_pattern
+      build_dir = output.match(build_dir_pattern)&.[](1)&.strip
+      if build_dir
+        output = output.gsub(build_dir, "<build dir>")
+      else
+        raise "build_dir_pattern #{build_dir_pattern.inspect} not found in output:\n#{output}"
+      end
+    end
+
+    env_sections = extract_env_sections(output)
+
+    if env_sections.size == 1
+      # Single section mode (e.g., CI tests)
+      @env_hash = env_sections[0]
+    elsif env_sections.size == 2
+      # Diff mode (before/after comparison)
+      before_hash = env_sections[0]
+      after_hash = env_sections[1]
+
+      @path_before = before_hash["PATH"]
+      @path_after = after_hash["PATH"]
+
+      non_path_before = before_hash.except("PATH")
+      non_path_after = after_hash.except("PATH")
+
+      @added = (non_path_after.keys - non_path_before.keys).sort.map { |k| "#{k}=#{non_path_after[k]}" }
+      @env_hash = after_hash
+    elsif env_sections.size > 2
+      raise "Too many print markers in output found:\n#{output}"
+    else
+      raise "Did not find any print markers in output:\n#{output}"
+    end
+  end
+
+  private def extract_env_sections(output, start_marker: "## PRINTING ENV ##", end_marker: "## PRINTING ENV DONE ##")
+    sections = []
+    in_section = false
+    current_env = {}
+
+    output.each_line do |line|
+      clean = line.gsub(/^\s*remote:\s*/, "").strip
+      case clean
+      when start_marker
+        in_section = true
+        current_env = {}
+      when end_marker
+        sections << current_env
+        in_section = false
+      else
+        if in_section && clean.include?("=")
+          key, value = clean.split("=", 2)
+          current_env[key] = value
+        end
+      end
+    end
+    sections
+  end
+end
+
+private def extract_remote_lines(output, start_marker:, end_marker:)
+  lines = []
+  in_section = false
+
+  output.each_line do |line|
+    clean = line.gsub(/^\s*remote:\s*/, "").strip
+    case clean
+    when start_marker
+      in_section = true
+    when end_marker
+      in_section = false
+    else
+      if in_section
+        lines << clean
+      end
+    end
+  end
+  lines
+end
diff --git a/spec/unit/bash_functions_spec.rb b/spec/unit/bash_functions_spec.rb
new file mode 100644
index 000000000..a0ea0fd41
--- /dev/null
+++ b/spec/unit/bash_functions_spec.rb
@@ -0,0 +1,280 @@
+require "spec_helper"
+
+describe "Bash functions" do
+  describe "output::error" do
+    it "prints" do
+      Dir.mktmpdir do |dir|
+        Pathname(dir).join("does-not-exist").expand_path
+        out = exec_with_bash_file(code: <<~EOM, file: bash_functions_file, strip_output: true)
+          output::error <<EOF
+          Error: Header
+
+          Error summary.
+          EOF
+        EOM
+
+        expect(out.strip).to eq(<<~EOM.strip)
+          \e[1;31m !     Error: Header\e[0m
+          \e[1;31m !     \e[0m
+          \e[1;31m !     Error summary.\e[0m
+        EOM
+      end
+    end
+  end
+
+  describe "metrics" do
+    it "does not error when collecting metrics and the target file is not set" do
+      Dir.mktmpdir do |dir|
+        Pathname(dir).join("does-not-exist").expand_path
+        out = exec_with_bash_file(code: <<~EOM, file: bash_functions_file, strip_output: true)
+          build_data::kv_string "ruby_version" "3.3.0"
+          build_data::kv_raw "ruby_major" "3"
+
+          build_data::print_bin_report_json
+        EOM
+
+        expect(out).to eq("")
+      end
+    end
+
+    it "prints error when report env var is set to a non-existent file" do
+      Dir.mktmpdir do |dir|
+        file = Pathname(dir).join("does-not-exist").expand_path
+        out = exec_with_bash_file(code: <<~EOM, file: bash_functions_file, strip_output: false, raise_on_fail: false)
+          export HEROKU_RUBY_BUILD_REPORT_FILE="#{file}"
+          export BUILD_DATA_FILE="#{file}"
+          build_data::print_bin_report_json
+        EOM
+
+        expect($?.success?).to be_falsey, "Expected command failure but got unexpected success. Output:\n\n#{out}"
+        expect(out).to include("No such file or directory")
+      end
+    end
+
+    it "detects env var mutation and raise an error" do
+      Dir.mktmpdir do |dir|
+        file = Pathname(dir).join("does-not-exist").expand_path
+        out = exec_with_bash_file(code: <<~EOM, file: bash_functions_file, strip_output: false, raise_on_fail: false)
+          export BUILD_DATA_FILE="#{file}"
+          build_data::print_bin_report_json
+        EOM
+
+        expect($?.success?).to be_falsey, "Expected command failure but got unexpected success. Output:\n\n#{out}"
+        expect(out).to include("Error: HEROKU_RUBY_BUILD_REPORT_FILE does not match BUILD_DATA_FILE")
+      end
+    end
+
+    it "kv_duration_since" do
+      out = exec_with_bash_file(code: <<~EOM, file: bash_functions_file, strip_output: false)
+        build_data::init "$(mktemp -d)"
+        build_data::clear
+
+        timer=$(build_data::current_unix_realtime)
+        sleep 0.1
+        build_data::kv_duration_since "ruby_install_ms" "${timer}"
+        build_data::print_bin_report_json
+      EOM
+
+      begin
+        ruby_install_s = JSON.parse(out).fetch("ruby_install_ms").to_f
+        expect(ruby_install_s).to be_between(0.1, 1)
+      rescue
+        puts "Output: #{out}"
+        raise
+      end
+    end
+
+    it "kv_string" do
+      out = exec_with_bash_file(code: <<~EOM, file: bash_functions_file, strip_output: false)
+        build_data::init "$(mktemp -d)"
+        build_data::clear
+
+        build_data::kv_string "ruby_version" "3.3.0"
+        build_data::print_bin_report_json
+      EOM
+
+      expect(out).to eq(<<~EOM)
+        {
+          "ruby_version": "3.3.0"
+        }
+      EOM
+    end
+
+    it "kv_raw" do
+      out = exec_with_bash_file(code: <<~EOM, file: bash_functions_file, strip_output: false)
+        build_data::init "$(mktemp -d)"
+        build_data::clear
+
+        build_data::kv_raw "ruby_minor" "3"
+        build_data::print_bin_report_json
+      EOM
+
+      expect(out).to eq(<<~EOM)
+        {
+          "ruby_minor": 3
+        }
+      EOM
+    end
+  end
+
+  it "fails on old stacks" do
+    out = exec_with_bash_functions(<<~EOM, raise_on_fail: false)
+      build_data::init "$(mktemp -d)"
+      build_data::clear
+
+      checks::ensure_supported_stack "heroku-20"
+    EOM
+
+    expect($?.success?).to be_falsey, "Expected command failure but got unexpected success. Output:\n\n#{out}"
+    expect(out).to include("This buildpack no longer supports the 'heroku-20' stack")
+  end
+
+  it "knows the latest stacks" do
+    out = exec_with_bash_functions(<<~EOM)
+      checks::ensure_supported_stack "heroku-24"
+    EOM
+
+    expect(out).to be_empty
+  end
+
+  it "knows heroku-26" do
+    out = exec_with_bash_functions(<<~EOM)
+      checks::ensure_supported_stack "heroku-26"
+    EOM
+
+    expect(out).to be_empty
+  end
+
+  it "Detects jruby in the Gemfile.lock" do
+    Dir.mktmpdir do |dir|
+      dir = Pathname(dir)
+      dir.join("Gemfile.lock").write <<~EOM
+        RUBY VERSION
+           ruby 2.5.7p001 (jruby 9.2.13.0)
+      EOM
+
+      out = exec_with_bash_functions <<~EOM
+        which_java()
+        {
+          return 1
+        }
+
+        if detect_needs_java "#{dir}"; then
+          echo "jruby detected"
+        else
+          echo "nope"
+        fi
+      EOM
+
+      expect(out).to eq("jruby detected")
+
+      dir.join("Gemfile.lock").write <<~EOM
+      EOM
+
+      out = exec_with_bash_functions <<~EOM
+        which_java()
+        {
+          return 1
+        }
+
+        if detect_needs_java "#{dir}"; then
+          echo "jruby detected"
+        else
+          echo "nope"
+        fi
+      EOM
+
+      expect(out).to eq("nope")
+    end
+  end
+
+  it "Detects java for jruby detection" do
+    Dir.mktmpdir do |dir|
+      dir = Pathname(dir)
+      dir.join("Gemfile.lock").write <<~EOM
+        RUBY VERSION
+           ruby 2.5.7p001 (jruby 9.2.13.0)
+      EOM
+
+      out = exec_with_bash_functions <<~EOM
+        build_data::init "$(mktemp -d)"
+        build_data::clear
+
+        which_java()
+        {
+          return 0
+        }
+
+        if detect_needs_java "#{dir}"; then
+          echo "jruby detected"
+        else
+          echo "already installed"
+        fi
+      EOM
+
+      expect(out).to eq("already installed")
+    end
+  end
+
+  def bash_functions_file
+    root_dir.join("bin", "support", "bash_functions.sh")
+  end
+
+  def exec_with_bash_file(file:, code:, stack: "heroku-24", raise_on_fail: true, strip_output: true)
+    contents = <<~EOM
+      #! /usr/bin/env bash
+      set -eu
+
+      STACK="#{stack}"
+
+      #{file.read}
+
+      #{code}
+    EOM
+
+    file = Tempfile.new
+    file.write(contents)
+    file.close
+    FileUtils.chmod("+x", file.path)
+
+    out = nil
+    success = false
+    begin
+      Timeout.timeout(60) do
+        out = `#{file.path} 2>&1`
+        out = out.strip if strip_output
+        success = $?.success?
+      end
+    rescue Timeout::Error
+      out = "Command timed out"
+      success = false
+    end
+
+    if raise_on_fail && !success
+      message = <<~EOM
+        Contents:
+
+        #{contents.lines.map.with_index { |line, number| "  #{number.next} #{line.chomp}" }.join("\n")}
+
+        Expected running script to succeed, but it did not. If this was expected, use `raise_on_fail: false`
+
+        Output:
+
+          #{out}
+      EOM
+
+      raise message
+    else
+      out
+    end
+  end
+
+  def exec_with_bash_functions(code, stack: "heroku-24", raise_on_fail: true)
+    exec_with_bash_file(
+      code: code,
+      file: bash_functions_file,
+      stack: stack,
+      raise_on_fail: raise_on_fail
+    )
+  end
+end
diff --git a/spec/upgrade_ruby_spec.rb b/spec/upgrade_ruby_spec.rb
deleted file mode 100644
index 975be7a2e..000000000
--- a/spec/upgrade_ruby_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require 'spec_helper'
-
-describe "Upgrading ruby apps" do
-  it "upgrades from 2.0.0 to 2.1.0" do
-    Hatchet::Runner.new("mri_200").deploy do |app|
-      expect(app.run("ruby -v")).to match("2.0.0")
-
-      `echo "" > Gemfile; rm Gemfile.lock`
-      `env BUNDLE_GEMFILE=./Gemfile bundle install`
-      `echo "ruby '2.1.0'" > Gemfile`
-      `git add . ; git commit -m update-ruby`
-      app.push!
-      expect(app.output).to match("2.1.0")
-      expect(app.run("ruby -v")).to match("2.1.0")
-    end
-  end
-end
diff --git a/spec/user_env_compile_edge_case_spec.rb b/spec/user_env_compile_edge_case_spec.rb
deleted file mode 100644
index 1af8667c9..000000000
--- a/spec/user_env_compile_edge_case_spec.rb
+++ /dev/null
@@ -1,28 +0,0 @@
-require 'spec_helper'
-
-describe "User env compile" do
-  it "should not cause problems with warnings" do
-    app = Hatchet::Runner.new("mri_210", labs: "user-env-compile")
-    app.setup!
-    app.set_config("RUBY_HEAP_MIN_SLOTS" => "1000000")
-    app.deploy do |app|
-      expect(app.run("bundle version")).to match(LanguagePack::Ruby::BUNDLER_VERSION)
-    end
-  end
-
-  it "DATABASE_URL is present even without user-env-compile" do
-    Hatchet::Runner.new("database_url_expected_in_rakefile").deploy do |app|
-      expect(app.output).to match("Asset precompilation completed")
-    end
-  end
-
-  it "allows weird characters in the env" do
-    app = Hatchet::Runner.new("rails41_scaffold")
-    app.setup!
-    app.set_config("BAD VALUE"      => %Q{ )(*&^%$#'$'\n''@!~\'\ })
-    app.set_config(%Q{ un"matched } => "bad key" )
-    app.deploy do |app|
-      expect(app.output).to match("Launching")
-    end
-  end
-end
diff --git a/support/s3/hmac b/support/s3/hmac
deleted file mode 100755
index 5aa074a0d..000000000
--- a/support/s3/hmac
+++ /dev/null
@@ -1,79 +0,0 @@
-#!/bin/bash
-# Implement HMAC functionality on top of the OpenSSL digest functions.
-# licensed under the terms of the GNU GPL v2
-# Copyright 2007 Victor Lowther <victor.lowther@gmail.com>
-
-die() {
-  echo $*
-  exit 1
-}
-
-check_deps() {
-  local res=0
-  while [ $# -ne 0 ]; do
-    which "${1}" >& /dev/null || { res=1; echo "${1} not found."; }
-    shift
-  done
-  (( res == 0 )) || die "aborting."
-}
-
-# write a byte (passed as hex) to stdout
-write_byte() {
-  # $1 = byte to write
-  printf "\\x$(printf "%x" ${1})"
-}
-
-# make an hmac pad out of a key.
-# this is not the most secure way of doing it, but it is
-# the most expedient.
-make_hmac_pad() {
-  # using key in file $1 and byte in $2, create the appropriate hmac pad
-  # Pad keys out to $3 bytes
-  # if key is longer than $3, use hash $4 to hash the key first.
-  local x y a size remainder oifs
-  (( remainder = ${3} ))
-  # in case someone else was messing with IFS.
-  for x in $(echo -n "${1}" | od -v -t u1 | cut -b 9-);
-  do
-    write_byte $((${x} ^ ${2}))
-    (( remainder -= 1 ))
-  done
-  for ((y=0; remainder - y ;y++)); do
-    write_byte $((0 ^ ${2}))
-  done
-}
-
-# utility functions for making hmac pads
-hmac_ipad() {
-  make_hmac_pad "${1}" 0x36 ${2} "${3}"
-}
-
-hmac_opad() {
-  make_hmac_pad "${1}" 0x5c ${2} "${3}"
-}
-
-# hmac something
-do_hmac() {
-  # $1 = algo to use.  Must be one that openssl knows about
-  # $2 = keyfile to use
-  # $3 = file to hash.  uses stdin if none is given.
-  # accepts input on stdin, leaves it on stdout.
-  # Output is binary, if you want something else pipe it accordingly.
-  local blocklen keysize x
-  case "${1}" in
-    sha) blocklen=64 ;;
-    sha1) blocklen=64 ;;
-    md5) blocklen=64 ;;
-    md4) blocklen=64 ;;
-    sha256) blocklen=64 ;;
-    sha512) blocklen=128 ;;
-    *) die "Unknown hash ${1} passed to hmac!" ;;
-  esac
-  cat <(hmac_ipad ${2} ${blocklen} "${1}") "${3:--}" | openssl dgst "-${1}" -binary | \
-  cat <(hmac_opad ${2} ${blocklen} "${1}") - | openssl dgst "-${1}" -binary
-}
-
-[[ ${1} ]] || die "Must pass the name of the hash function to use to ${0}".
-
-check_deps od openssl
-do_hmac "${@}"
diff --git a/support/s3/s3 b/support/s3/s3
deleted file mode 100755
index d5cf94d2a..000000000
--- a/support/s3/s3
+++ /dev/null
@@ -1,223 +0,0 @@
-#!/bin/bash
-# basic amazon s3 operations
-# Licensed under the terms of the GNU GPL v2
-# Copyright 2007 Victor Lowther <victor.lowther@gmail.com>
-
-set -e
-
-basedir="$( cd -P "$( dirname "$0" )" && pwd )"
-PATH="$basedir:$PATH"
-
-# print a message and bail
-die() {
-  echo $*
-  exit 1
-}
-
-# check to see if the variable name passed exists and holds a value.
-# Die if it does not.
-check_or_die() {
-  [[ ${!1} ]] || die "Environment variable ${1} is not set."
-}
-
-# check to see if we have all the needed S3 variables defined.
-# Bail if we do not.
-check_s3() {
-  local sak x
-  for x in S3_ACCESS_KEY_ID S3_SECRET_ACCESS_KEY; do
-    check_or_die ${x};
-  done
-  sak="$(echo -n $S3_SECRET_ACCESS_KEY | wc -c)"
-  (( ${sak%%[!0-9 ]*} == 40 )) || \
-    die "S3 Secret Access Key is not exactly 40 bytes long.  Please fix it."
-}
-# check to see if our external dependencies exist
-check_dep() {
-  local res=0
-  while [[ $# -ne 0 ]]; do
-    which "${1}" >& /dev/null || { res=1; echo "${1} not found."; }
-    shift
-  done
-  (( res == 0 )) || die "aborting."
-}
-
-check_deps() {
-  check_dep openssl date hmac cat grep curl
-  check_s3
-}
-
-urlenc() {
-  # $1 = string to url encode
-  # output is on stdout
-  # we don't urlencode everything, just enough stuff.
-  echo -n "${1}" |
-  sed 's/%/%25/g
-       s/ /%20/g
-       s/#/%23/g
-       s/\$/%24/g
-       s/\&/%26/g
-       s/+/%2b/g
-       s/,/%2c/g
-       s/:/%3a/g
-       s/;/%3b/g
-       s/?/%3f/g
-       s/@/%40/g
-       s/	/%09/g'
-}
-
-xmldec() {
-  # no parameters.
-  # accept input on stdin, put it on stdout.
-  # patches accepted to get more stuff
-  sed 's/\&quot;/\"/g
-       s/\&amp;/\&/g
-       s/\&lt;/</g
-       s/\&gt;/>/g'
-}
-
-## basic S3 functionality.  x-amz-header functionality is not implemented.
-# make an S3 signature string, which will be output on stdout.
-s3_signature_string() {
-  # $1 = HTTP verb
-  # $2 = date string, must be in UTC
-  # $3 = bucket name, if any
-  # $4 = resource path, if any
-  # $5 = content md5, if any
-  # $6 = content MIME type, if any
-  # $7 = canonicalized headers, if any
-  # signature string will be output on stdout
-  local verr="Must pass a verb to s3_signature_string!"
-  local verb="${1:?verr}"
-  local bucket="${3}"
-  local resource="${4}"
-  local derr="Must pass a date to s3_signature_string!"
-  local date="${2:?derr}"
-  local mime="${6}"
-  local md5="${5}"
-  local headers="${7}"
-  printf "%s\n%s\n%s\n%s\n%s\n%s%s" \
-    "${verb}" "${md5}" "${mime}" "${date}" \
-    "${headers}" "${bucket}" "${resource}" | \
-    hmac sha1 "${S3_SECRET_ACCESS_KEY}" | openssl base64 -e -a
-}
-
-# cheesy, but it is the best way to have multiple headers.
-curl_headers() {
-  # each arg passed will be output on its own line
-  local parms=$#
-  for ((;$#;)); do
-    echo "header = \"${1}\""
-    shift
-  done
-}
-
-s3_curl() {
-  # invoke curl to do all the heavy HTTP lifting
-  # $1 = method (one of GET, PUT, or DELETE. HEAD is not handled yet.)
-  # $2 = remote bucket.
-  # $3 = remote name
-  # $4 = local name.
-  local bucket remote date sig md5 arg inout headers
-  # header handling is kinda fugly, but it works.
-  bucket="${2:+/${2}}/" # slashify the bucket
-  remote="$(urlenc "${3}")" # if you don't, strange things may happen.
-  stdopts="--connect-timeout 10 --fail --silent"
-  [[ $CURL_S3_DEBUG == true ]] && stdopts="${stdopts} --show-error --fail"
-  case "${1}" in
-   GET) arg="-o" inout="${4:--}" # stdout if no $4
-	;;
-   PUT) [[ ${2} ]] || die "PUT can has bucket?"
-        if [[ ! ${3} ]]; then
-	  arg="-X PUT"
-	  headers[${#headers[@]}]="Content-Length: 0"
-	elif [[ -f ${4} ]]; then
-          md5="$(openssl dgst -md5 -binary "${4}"|openssl base64 -e -a)"
-	  arg="-T" inout="${4}"
-	  headers[${#headers[@]}]="x-amz-acl: public-read"
-	  headers[${#headers[@]}]="Expect: 100-continue"
-	else
-	  die "Cannot write non-existing file ${4}"
-        fi
-	;;
-   DELETE) arg="-X DELETE"
-           ;;
-   HEAD) arg="-I" ;;
-   *) die "Unknown verb ${1}.  It probably would not have worked anyways." ;;
-  esac
-  date="$(TZ=UTC date '+%a, %e %b %Y %H:%M:%S %z')"
-  sig=$(s3_signature_string ${1} "${date}" "${bucket}" "${remote}" "${md5}" "" "x-amz-acl:public-read")
-
-  headers[${#headers[@]}]="Authorization: AWS ${S3_ACCESS_KEY_ID}:${sig}"
-  headers[${#headers[@]}]="Date: ${date}"
-  [[ ${md5} ]] && headers[${#headers[@]}]="Content-MD5: ${md5}"
-    curl ${arg} "${inout}" ${stdopts} -o - -K <(curl_headers "${headers[@]}") \
-       "http://s3.amazonaws.com${bucket}${remote}"
-  return $?
-}
-
-s3_put() {
-  # $1 = remote bucket to put it into
-  # $2 = remote name to put
-  # $3 = file to put.  This must be present if $2 is.
-  s3_curl PUT "${1}" "${2}" "${3:-${2}}"
-  return $?
-}
-
-s3_get() {
-  # $1 = bucket to get file from
-  # $2 = remote file to get
-  # $3 = local file to get into. Will be overwritten if it exists.
-  #      If this contains a path, that path must exist before calling this.
-  s3_curl GET "${1}" "${2}" "${3:-${2}}"
-  return $?
-}
-
-s3_test() {
-  # same args as s3_get, but uses the HEAD verb instead of the GET verb.
-  s3_curl HEAD "${1}" "${2}" >/dev/null
-  return $?
-}
-
-# Hideously ugly, but it works well enough.
-s3_buckets() {
-  s3_get |grep -o '<Name>[^>]*</Name>' |sed 's/<[^>]*>//g' |xmldec
-  return $?
-}
-
-# this will only return the first thousand entries, alas
-# Mabye some kind soul can fix this without writing an XML parser in bash?
-# Also need to add xml entity handling.
-s3_list() {
-  # $1 = bucket to list
-  [ "x${1}" == "x" ] && return 1
-  s3_get "${1}" |grep -o '<Key>[^>]*</Key>' |sed 's/<[^>]*>//g'| xmldec
-  return $?
-}
-
-s3_delete() {
-  # $1 = bucket to delete from
-  # $2 = item to delete
-  s3_curl DELETE "${1}" "${2}"
-  return $?
-}
-
-# because this uses s3_list, it suffers from the same flaws.
-s3_rmrf() {
-  # $1 = bucket to delete everything from
-  s3_list "${1}" | while read f; do
-    s3_delete "${1}" "${f}";
-  done
-}
-
-check_deps
-case $1 in
-  put) shift; s3_put "$@" ;;
-  get) shift; s3_get "$@" ;;
-  rm) shift; s3_delete "$@" ;;
-  ls) shift; s3_list "$@" ;;
-  test) shift; s3_test "$@" ;;
-  buckets) s3_buckets ;;
-  rmrf) shift; s3_rmrf "$@" ;;
-  *) die "Unknown command ${1}."
-    ;;
-esac
diff --git a/tmp/.gitkeep b/tmp/.gitkeep
new file mode 100644
index 000000000..e69de29bb
diff --git a/vendor/dotenv.rb b/vendor/dotenv.rb
deleted file mode 100644
index cca1c077d..000000000
--- a/vendor/dotenv.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-# imports contents of .env file into ENV
-file = File.expand_path("../../.env", __FILE__)
-if File.exists?(file)
-  File.read(file).split("\n").map {|x| x.split("=") }.each do |k,v|
-    ENV[k.strip] = v.strip
-  end
-end
diff --git a/vendor/lpxc.rb b/vendor/lpxc.rb
deleted file mode 100644
index 2e3ed30c0..000000000
--- a/vendor/lpxc.rb
+++ /dev/null
@@ -1,177 +0,0 @@
-require 'time'
-require 'net/http'
-require 'uri'
-require 'thread'
-require 'timeout'
-
-class Lpxc
-
-  #After parsing opts and initializing defaults, the initializer
-  #will start 2 threads. One thread for sending HTTP requests and another
-  #thread for flushing log messages to the outlet thread periodically.
-  #:hash => {}:: A data structure for grouping log messages by token.
-  #:request_queue => SizedQueue.new::  Contains HTTP requests ready for outlet thread to deliver to logplex.
-  #:default_token => nil:: You can specify a token that will be used for any call to Lpxc#puts that doesn't include a token.
-  #:structured_data => '-':: Structured-data field for syslog headers. Ignored by logplex.
-  #:msgid => '-'::  Msg ID field for syslog headers. Ignored by logplex.
-  #:procid => 'lpxc':: Proc ID field for syslog headers. This will show up in the Heroku logs tail command as: app [lpxc].
-  #:hostname => 'myhost':: Hostname field for syslog headers. Ignored by logplex.
-  #:max_reqs_per_conn => 1_000:: Number of requests before we re-establish our keep-alive connection to logplex.
-  #:conn_timeout => 2:: Number of seconds before timing out a sindle request to logplex.
-  #:batch_size => 300:: Max number of log messages inside single HTTP request.
-  #:flush_interval => 0.5:: Fractional number of seconds before flushing all log messages in buffer to logplex.
-  #:logplex_url => \'https://east.logplex.io/logs':: HTTP server that will accept our log messages.
-  #:disable_delay_flush => nil:: Force flush only batch_size is reached.
-  def initialize(opts={})
-    @hash_lock = Mutex.new
-    @hash              = opts[:hash]              || Hash.new
-    @request_queue     = opts[:request_queue]     || SizedQueue.new(1)
-    @default_token     = opts[:default_token]     || ENV['LOGPLEX_DEFAULT_TOKEN']
-    @structured_data   = opts[:structured_data]   || "-"
-    @msgid             = opts[:msgid]             || "-"
-    @procid            = opts[:procid]            || "lpxc"
-    @hostname          = opts[:hostname]          || "myhost"
-    @max_reqs_per_conn = opts[:max_reqs_per_conn] || 1_000
-    @conn_timeout      = opts[:conn_timeout]      || 2
-    @batch_size        = opts[:batch_size]        || 300
-    @flush_interval    = opts[:flush_interval]    || 0.5
-    @logplex_url       = URI(opts[:logplex_url]   || ENV["LOGPLEX_URL"] ||
-      raise("Must set logplex url."))
-
-    #Keep track of the number of requests that the outlet
-    #is processing. This value is used by the wait function.
-    @req_in_flight = 0
-
-    #Initialize the last_flush to an arbitrary time.
-    @last_flush = Time.now + @flush_interval
-
-    #Start the processing threads.
-    Thread.new {outlet}
-    Thread.new {delay_flush} if opts[:disable_delay_flush].nil?
-  end
-
-  #The interface to publish logs into the stream.
-  #This function will set the log message to the current time in UTC.
-  #If the buffer for this token's log messages is full, it will flush the buffer.
-  def puts(msg, tok=@default_token)
-    @hash_lock.synchronize do
-      #Messages are grouped by their token since 1 http request
-      #to logplex must only contain log messages belonging to a single token.
-      q = @hash[tok] ||= SizedQueue.new(@batch_size)
-      #This call will block if the queue is full.
-      #However this should never happen since the next command will flush
-      #the queue if we add the last item.
-      q.enq({:t => Time.now.utc, :token => tok, :msg => msg})
-      flush if q.size == q.max
-    end
-  end
-
-  #Wait until all of the data has been cleared from memory.
-  #This is useful if you don't want your program to exit before
-  #we are able to deliver log messages to logplex.
-  def wait
-    sleep(0.1) until
-      @hash.length.zero? &&
-      @request_queue.empty? &&
-      @req_in_flight.zero?
-  end
-
-  private
-
-  #Take a lock to read all of the buffered messages.
-  #Once we have read the messages, we make 1 http request for the batch.
-  #We pass the request off into the request queue so that the request
-  #can be sent to LOGPLEX_URL.
-  def flush
-    @hash.each do |tok, msgs|
-      #Copy the messages from the queue into the payload array.
-      payloads = []
-      msgs.size.times {payloads << msgs.deq}
-      return if payloads.nil? || payloads.empty?
-
-      #Use the payloads array to build a string that will be
-      #used as the http body for the logplex request.
-      body = ""
-      payloads.flatten.each do |payload|
-        body += "#{fmt(payload)}"
-      end
-
-      #Build a new HTTP request and place it into the queue
-      #to be processed by the HTTP connection.
-      req = Net::HTTP::Post.new(@logplex_url.path)
-      req.basic_auth("token", tok)
-      req.add_field('Content-Type', 'application/logplex-1')
-      req.body = body
-      @request_queue.enq(req)
-      @hash.delete(tok)
-      @last_flush = Time.now
-    end
-  end
-
-
-  #This method must be called in order for the messages to be sent to Logplex.
-  #This method also spawns a thread that allows the messages to be batched.
-  #Messages are flushed from memory every 500ms or when we have 300 messages,
-  #whichever comes first.
-  def delay_flush
-    loop do
-      begin
-        if interval_ready?
-          @hash_lock.synchronize {flush}
-        end
-        sleep(0.01)
-      rescue => e
-      end
-    end
-  end
-
-  def interval_ready?
-    (Time.now.to_f - @last_flush.to_f).abs >= @flush_interval
-  end
-
-  #Format the user message into RFC5425 format.
-  #This method also prepends the length to the message.
-  def fmt(data)
-    pkt = "<190>1 "
-    pkt += "#{data[:t].strftime("%Y-%m-%dT%H:%M:%S+00:00")} "
-    pkt += "#{@hostname} "
-    pkt += "#{data[:token]} "
-    pkt += "#{@procid} "
-    pkt += "#{@msgid} "
-    pkt += "#{@structured_data} "
-    pkt += data[:msg]
-    "#{pkt.size} #{pkt}"
-  end
-
-  #We use a keep-alive connection to send data to LOGPLEX_URL.
-  #Each request will contain one or more log messages.
-  def outlet
-    loop do
-      http = Net::HTTP.new(@logplex_url.host, @logplex_url.port)
-      http.use_ssl = true if @logplex_url.scheme == 'https'
-      begin
-        http.start do |conn|
-          num_reqs = 0
-          while num_reqs < @max_reqs_per_conn
-            #Blocks waiting for a request.
-            req = @request_queue.deq
-            @req_in_flight += 1
-            resp = nil
-            begin
-              Timeout::timeout(@conn_timeout) {resp = conn.request(req)}
-            rescue => e
-              next
-            ensure
-              @req_in_flight -= 1
-            end
-            num_reqs += 1
-          end
-        end
-      rescue => e
-      ensure
-        http.finish if http.started?
-      end
-    end
-  end
-
-end
diff --git a/vendor/syck_hack.rb b/vendor/syck_hack.rb
deleted file mode 100644
index 454f722c3..000000000
--- a/vendor/syck_hack.rb
+++ /dev/null
@@ -1,64 +0,0 @@
-# :stopdoc:
-
-# Hack to handle syck's DefaultKey bug
-#
-# This file is always loaded AFTER either syck or psych are already
-# loaded. It then looks at what constants are available and creates
-# a consistent view on all rubys.
-#
-# All this is so that there is always a YAML::Syck::DefaultKey
-# class no matter if the full yaml library has loaded or not.
-#
-
-$: << ENV['BUNDLER_LIB_PATH'] if ENV['BUNDLER_LIB_PATH']
-require 'bundler/psyched_yaml'
-
-module YAML
-  # In newer 1.9.2, there is a Syck toplevel constant instead of it
-  # being underneith YAML. If so, reference it back under YAML as
-  # well.
-  if defined? ::Syck
-    Syck = ::Syck
-
-  # Otherwise, if there is no YAML::Syck, then we've got just psych
-  # loaded, so lets define a stub for DefaultKey.
-  elsif !defined? YAML::Syck
-    module Syck
-      class DefaultKey
-      end
-    end
-  end
-
-  # Now that we've got something that is always here, define #to_s
-  # so when code tries to use this, it at least just shows up like it
-  # should.
-  module Syck
-    class DefaultKey
-      def to_s
-        '='
-      end
-    end
-  end
-end
-
-# Sometime in the 1.9 dev cycle, the Syck constant was moved from under YAML
-# to be a toplevel constant. So gemspecs created under these versions of Syck
-# will have references to Syck::DefaultKey.
-#
-# So we need to be sure that we reference Syck at the toplevel too so that
-# we can always load these kind of gemspecs.
-#
-if !defined?(Syck)
-  Syck = YAML::Syck
-end
-
-# Now that we've got Syck setup in all the right places, store
-# a reference to the DefaultKey class inside Gem. We do this so that
-# if later on YAML, etc are redefined, we've still got a consistent
-# place to find the DefaultKey class for comparison.
-
-module Gem
-  SyckDefaultKey = YAML::Syck::DefaultKey
-end
-
-# :startdoc: