Publish testflows/machine-examples to Docker Hub

- Dockerfile builds every program with make check, which refuses a binary
  that is not static x86_64, and copies them into an empty image at
  /examples/<name>, with LICENSE. linux/amd64 only: a machine is x86_64.
  hello-world is the entrypoint.
- .github/workflows/image.yml, run by hand, pushes :<YYYYMMDD-HHMM> and
  :latest, then runs the pushed image to check it.
- README: building the image yourself.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BJu3r5JhoqtUHitojYU7xh

Author: vzakaznikov

.dockerignore

@@ -0,0 +1,3 @@
+.git
+bin
+compose

.github/workflows/image.yml

@@ -0,0 +1,58 @@
+# Copyright 2026 Katteli Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Builds testflows/machine-examples and pushes it to Docker Hub as
+# :<YYYYMMDD-HHMM> and :latest. Run by hand: a new image is a release.
+name: 🐳 Publish image
+
+on:
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+env:
+  IMAGE: testflows/machine-examples
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Version
+        id: version
+        run: echo "version=$(date -u +%Y%m%d-%H%M)" >> "$GITHUB_OUTPUT"
+
+      - uses: docker/setup-buildx-action@v3
+
+      - uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - uses: docker/build-push-action@v6
+        with:
+          context: .
+          platforms: linux/amd64
+          build-args: VERSION=${{ steps.version.outputs.version }}
+          push: true
+          tags: |
+            ${{ env.IMAGE }}:${{ steps.version.outputs.version }}
+            ${{ env.IMAGE }}:latest
+
+      - name: Check the pushed image
+        run: |
+          docker run --rm --platform linux/amd64 "$IMAGE:${{ steps.version.outputs.version }}" | grep -q "Hello from TestFlows Machine"
+          echo "### Published $IMAGE:${{ steps.version.outputs.version }} and :latest" >> "$GITHUB_STEP_SUMMARY"

Dockerfile

@@ -0,0 +1,42 @@
+# Copyright 2026 Katteli Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# The testflows/machine-examples image: every program, static, at
+# /examples/<name>. A machine is x86_64, so the image is linux/amd64 only.
+FROM --platform=linux/amd64 debian:bookworm-slim AS build
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends gcc libc6-dev make file \
+ && rm -rf /var/lib/apt/lists/*
+WORKDIR /src
+COPY Makefile ./
+COPY hello hello
+COPY races races
+COPY starvation starvation
+COPY stress stress
+RUN make check
+
+# Nothing but the programs: they are static, so they need no libraries, and
+# a disk built from this image carries only what it runs.
+FROM scratch
+ARG VERSION=dev
+LABEL org.opencontainers.image.title="TestFlows Machine examples" \
+      org.opencontainers.image.description="Programs to run on TestFlows Machine" \
+      org.opencontainers.image.url="https://testflows.com/machine/" \
+      org.opencontainers.image.source="https://github.com/testflows/Machine-Examples" \
+      org.opencontainers.image.licenses="Apache-2.0" \
+      org.opencontainers.image.vendor="Katteli Inc." \
+      org.opencontainers.image.version="${VERSION}"
+COPY --from=build /src/bin/ /examples/
+COPY LICENSE /LICENSE
+ENTRYPOINT ["/examples/hello-world"]

README.md

@@ -62,6 +62,13 @@ machine disks build --binary bin/data-race race -- 8
 machine create --disk race
 ```
 
+Or build the image itself, the same one `testflows/machine-examples` is:
+
+```bash
+docker build -t machine-examples .
+machine disks build --image machine-examples --entrypoint /examples/data-race race -- 8
+```
+
 ## 🐳 Compose Environments
 
 `compose/` holds whole environments rather than programs: a docker compose