Create Kingston Docker image build optimization scenario

scenarios/kingston/README.md

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+# "Kingston": Docker Image Build Optimization
+
+## Introduction
+
+Welcome to the Kingston scenario! This challenge focuses on optimizing Docker image build times for a Ruby on Rails application. You'll be working with a real-world Dockerfile that has several optimization opportunities.
+
+## Scenario Description
+
+You have been given a Ruby on Rails application with a poorly optimized Dockerfile that takes a long time to build. Your task is to optimize the Docker build process to achieve **at least a 10% reduction in build time** compared to the base implementation.
+
+## The Challenge
+
+The scenario includes:
+- **Dockerfile.base**: An unoptimized Dockerfile with multiple inefficiencies
+- **Dockerfile.optimized**: A pre-optimized version that you can study and improve further
+- **Sample Rails app**: A minimal Rails application for testing builds
+- **Timing script**: Automated build time comparison tool
+
+## Common Docker Optimization Techniques
+
+Here are some optimization strategies you might consider:
+
+### 1. **Layer Caching Optimization**
+- Order instructions from least to most frequently changing
+- Copy dependency files before application code
+- Use `.dockerignore` to exclude unnecessary files
+
+### 2. **Reduce Layer Count**
+- Combine multiple RUN statements
+- Chain commands with `&&`
+- Clean up in the same layer where packages are installed
+
+### 3. **Multi-stage Builds**
+- Separate build dependencies from runtime dependencies
+- Use a smaller base image for the final stage
+- Copy only necessary artifacts between stages
+
+### 4. **Base Image Selection**
+- Use more recent, optimized base images
+- Consider Alpine Linux for smaller images
+- Use official language-specific images when appropriate
+
+### 5. **Package Management**
+- Use `--no-install-recommends` for apt packages
+- Clean package caches in the same layer
+- Pin package versions for reproducible builds
+
+### 6. **Build Context Optimization**
+- Minimize build context size
+- Use `.dockerignore` effectively
+- Avoid sending unnecessary files to Docker daemon
+
+## Getting Started
+
+1. **Explore the current setup:**
+   ```bash
+   cd /home/admin/docker-optimization
+   ls -la
+   ```
+
+2. **Examine the base Dockerfile:**
+   ```bash
+   cat Dockerfile.base
+   ```
+
+3. **Study the optimized version:**
+   ```bash
+   cat Dockerfile.optimized
+   ```
+
+4. **Run the build time comparison:**
+   ```bash
+   ./time_builds.sh
+   ```
+
+## Success Criteria
+
+The scenario is considered complete when:
+- Both Dockerfiles build successfully
+- The optimized build is **at least 10% faster** than the base build
+- The optimization maintains the same functionality
+
+## Tips for Success
+
+- **Start with the obvious wins**: Look for repeated `RUN` commands, unnecessary downloads, and poor layer ordering
+- **Use Docker's build cache effectively**: Structure your Dockerfile to maximize cache hits
+- **Monitor build progress**: Use `docker build --progress=plain` to see detailed build steps
+- **Test iteratively**: Make small changes and test frequently
+- **Consider the application needs**: Don't break functionality while optimizing
+
+## Validation
+
+Run the check script to validate your solution:
+```bash
+/home/admin/agent/check.sh
+```
+
+This will verify that your optimization achieves the required 10% improvement in build time.
+
+## Files in this Scenario
+
+- `Dockerfile.base` - The unoptimized Dockerfile (starting point)
+- `Dockerfile.optimized` - An optimized version to study and improve
+- `time_builds.sh` - Script to measure and compare build times
+- `setup_scenario.sh` - Initial scenario setup script
+- `Gemfile`, `Gemfile.lock` - Rails application dependencies
+- `entrypoint.sh` - Docker container entrypoint script
+- Sample Rails application files for realistic build testing
+
+Good luck with your Docker optimization challenge!

scenarios/kingston/ansible/playbook-debian.yml

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+---
+# ansible-playbook playbook-debian.yml -u admin --private-key=/path/to/private/key -i "$ip,"
+- name: Setup Docker Image Build Optimization scenario
+  hosts: all
+  tasks:
+  # OS packages and Docker installation
+  - name: Update packages and install prerequisites
+    become: true
+    package:
+      update_cache: yes
+      state: latest
+      name:
+        - apt-transport-https
+        - ca-certificates
+        - curl
+        - gnupg
+        - lsb-release
+        - bc
+
+  - name: Add Docker GPG key
+    become: true
+    apt_key:
+      url: https://download.docker.com/linux/debian/gpg
+      state: present
+
+  - name: Add Docker repository
+    become: true
+    apt_repository:
+      repo: "deb [arch=amd64] https://download.docker.com/linux/debian {{ ansible_distribution_release }} stable"
+      state: present
+
+  - name: Install Docker
+    become: true
+    package:
+      update_cache: yes
+      state: latest
+      name:
+        - docker-ce
+        - docker-ce-cli
+        - containerd.io
+
+  - name: Add admin user to docker group
+    become: true
+    user:
+      name: admin
+      groups: docker
+      append: yes
+
+  - name: Start and enable Docker service
+    become: true
+    systemd:
+      name: docker
+      state: started
+      enabled: yes
+
+  # Scenario files setup
+  - name: Create /home/admin/agent directory
+    ansible.builtin.file:
+      path: /home/admin/agent
+      owner: admin
+      group: admin
+      mode: a+wx
+      state: directory
+
+  - name: Copy Docker optimization scenario files
+    become: false
+    copy:
+      src: "{{ item.src }}"
+      dest: "{{ item.dest }}"
+      mode: "{{ item.mode | default('0644') }}"
+    with_items:
+      - { src: ../files/Dockerfile.base, dest: /home/admin/Dockerfile.base }
+      - { src: ../files/Dockerfile.optimized, dest: /home/admin/Dockerfile.optimized }
+      - { src: ../files/Gemfile, dest: /home/admin/Gemfile }
+      - { src: ../files/Gemfile.lock, dest: /home/admin/Gemfile.lock }
+      - { src: ../files/entrypoint.sh, dest: /home/admin/entrypoint.sh, mode: '0755' }
+      - { src: ../files/sidekiq_shutdown.rb, dest: /home/admin/sidekiq_shutdown.rb, mode: '0755' }
+      - { src: ../files/time_builds.sh, dest: /home/admin/time_builds.sh, mode: '0755' }
+      - { src: ../files/setup_scenario.sh, dest: /home/admin/setup_scenario.sh, mode: '0755' }
+
+  - name: Copy check.sh to agent directory
+    copy:
+      src: ../files/check.sh
+      dest: /home/admin/agent/check.sh
+      mode: '0755'
+
+  - name: Run scenario setup script
+    become: false
+    shell: /home/admin/setup_scenario.sh
+    args:
+      creates: /home/admin/docker-optimization
+
+  - name: Copy timing script to scenario directory
+    become: false
+    copy:
+      src: ../files/time_builds.sh
+      dest: /home/admin/docker-optimization/time_builds.sh
+      mode: '0755'

scenarios/kingston/files/.dockerignore

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+# .dockerignore for optimized Docker builds
+.git
+.gitignore
+README.md
+Dockerfile*
+.dockerignore
+*.md
+
+# Logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Coverage directory used by tools like istanbul
+coverage/
+
+# node_modules
+node_modules/
+
+# Test files
+test/
+spec/
+**/*_test.rb
+**/*_spec.rb
+
+# Development dependencies
+.bundle/vendor
+tmp/
+log/
+public/system/
+storage/
+
+# Editor files
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+
+# OS files
+.DS_Store
+Thumbs.db

scenarios/kingston/files/Dockerfile.base

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+FROM ubuntu:16.04
+ENV RUBY_VERSION=2.3.8
+ENV DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get update && \
+    apt-get install -y curl zlib1g-dev build-essential libssl-dev libreadline-dev libyaml-dev libsqlite3-dev \
+    sqlite3 \
+    git \
+    libxml2-dev \
+    libxslt1-dev \
+    libcurl4-openssl-dev \
+    software-properties-common \
+    libffi-dev \
+    tzdata \
+    # These three are wkhtmltopdf dependencies
+    wget libfontconfig1 libxrender1 \
+    libmysqlclient-dev openssl && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*
+
+RUN curl -sL https://deb.nodesource.com/setup_14.x | bash - \
+    && apt-get install -y nodejs
+
+RUN curl -O https://cache.ruby-lang.org/pub/ruby/2.3/ruby-2.3.8.tar.gz && \
+    tar -xzvf ruby-2.3.8.tar.gz && \
+    cd ruby-2.3.8 && \
+    ./configure --disable-install-doc && \
+    make && \
+    make install && \
+    cd / && \
+    rm -rf /tmp/ruby-2.3.8 ruby-2.3.8.tar.gz
+
+# This thing is used by wicked_pdf to generate pdfs from html
+RUN wget https://github.com/wkhtmltopdf/wkhtmltopdf/releases/download/0.12.3/wkhtmltox-0.12.3_linux-generic-amd64.tar.xz && \
+    tar vxf wkhtmltox-0.12.3_linux-generic-amd64.tar.xz && \
+    cp wkhtmltox/bin/wk* /usr/bin/
+
+COPY . /app
+
+WORKDIR /app
+
+COPY Gemfile Gemfile.lock ./
+
+# nokogiri needs to be installed separately or it will fail
+RUN gem install bundler -v 1.17.0 && \
+    gem install rake -v 13.0.6 --force && \
+    gem install nokogiri -v '1.9.1'
+
+RUN bundle install && \
+    bundle config --delete bin && \
+    rake rails:update:bin && \
+    bundle binstubs rails
+
+COPY . /app
+RUN chmod +x /app/entrypoint.sh /app/sidekiq_shutdown.rb
+
+RUN bundle exec rake RAILS_ENV=production assets:precompile
+
+CMD ["bundle","exec","rails","server","-p","8000"]