Canary image built on GitHub Actions

Author: alco

.github/workflows/sync_service_canary_image.yml

@@ -0,0 +1,131 @@
+name: Publish Electric canary image to Docker Hub
+
+on:
+  push:
+    # TMP for testing
+    # branches: ['main']
+    branches: ['alco/ci-build-public-docker-images']
+
+jobs:
+  derive_build_vars:
+    name: Derive build variables from the source code
+    runs-on: ubuntu-latest
+    outputs:
+      short_commit_sha: ${{ steps.vars.outputs.short_commit_sha }}
+      electric_version: ${{ steps.vars.outputs.electric_version }}
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          # It is crucial that we checkout the actual HEAD commit of the branch instead of
+          # GitHub's ephemeral merge commit that it creates for CI runs by default.
+          # We rely on the correct HEAD commit to be checked out in order to determine the
+          # correct ELECTRIC_VERSION to bake into the Docker image.
+          ref: ${{ github.event.pull_request.head.sha }}
+          # Also important to fetch the whole history since otherwise we won't get that tags
+          # that are required to determine the correct ELECTRIC_VERSION.
+          fetch-depth: 0
+          fetch-tags: true
+
+      - name: Determine SHORT_COMMIT_SHA and ELECTRIC_VERSION to use in the build step
+        id: vars
+        run: |
+          echo "short_commit_sha=$(
+            git rev-parse --short HEAD
+          )" >> $GITHUB_OUTPUT
+
+          echo "electric_version=$(
+            git describe --abbrev=7 --tags --always --first-parent --match '@core/sync-service@*' | sed -En 's|^@core/sync-service@||p'
+          )" >> $GITHUB_OUTPUT
+
+  build_and_push_image:
+    strategy:
+      matrix:
+        include:
+          - platform: linux/amd64
+            runner: ubuntu-latest
+          - platform: linux/arm64/v8
+            runner: ubuntu-24.04-arm
+    runs-on: ${{ matrix.runner }}
+    needs: [derive_build_vars]
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: docker/setup-buildx-action@v3
+
+      # Login to Docker Hub (create a token in Docker Hub, store as secret).
+      #- name: Log in to Docker Hub
+      #  uses: docker/login-action@v3
+      #  with:
+      #    registry: docker.io
+      #    username: ${{ secrets.DOCKERHUB_USERNAME }}
+      #    password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Build and push by digest
+        id: build
+        uses: docker/build-push-action@v6
+        with:
+          context: packages/sync-service
+          build-contexts: |
+            electric-telemetry=packages/electric-telemetry
+          build-args: |
+            ELECTRIC_VERSION=${{ needs.derive_build_vars.outputs.electric_version }}
+          platforms: ${{ matrix.platform }}
+          push: true
+          # push an untagged image and export its digest
+          # the subsequent merge job will assemble the manifest list and apply tags
+          outputs: type=image,name=electricsql/electric,push-by-digest=true
+          # tags: |
+          #   electricsql/electric:canary
+          #   electricsql/electric-canary:${{ env.SHORT_COMMIT_SHA }}
+          #   electricsql/electric-canary:latest
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+
+      # Save the digest so the merge job can find both platform images
+      - name: Export digest
+        run: |
+          mkdir -p /tmp/digests
+          echo "${{ steps.build.outputs.digest }}" > "/tmp/digests/${{ matrix.platform }}.digest"
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: digests-${{ matrix.platform }}
+          path: /tmp/digests/*.digest
+
+  publish_tagged_image:
+    needs: [derive_build_vars, build_and_push_image]
+    runs-on: ubuntu-latest
+    steps:
+      # - uses: docker/login-action@v3
+      #   with:
+      #     username: ${{ secrets.DOCKERHUB_USERNAME }}
+      #     password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - uses: docker/setup-buildx-action@v3
+
+      - uses: actions/download-artifact@v4
+        with:
+          pattern: digests-*
+          merge-multiple: true
+          path: /tmp/digests
+
+      - name: Create multi-arch manifest list
+        run: |
+          set -euo pipefail
+
+          cat /tmp/digests/*.digest
+
+          SINGLE_PLATFORM_IMAGES=$(
+            for f in /tmp/digests/*.digest; do
+              echo electricsql/electric@$(cat $f)
+            done
+          )
+
+          echo $SINGLE_PLATFORM_IMAGES
+
+          docker buildx imagetools create --dry-run \
+            -t electricsql/electric:canary \
+            -t electricsql/electric-canary:latest \
+            -t electricsql/electric-canary:${{ needs.derive_build_vars.outputs.short_commit_sha }}
+            $SINGLE_PLATFORM_IMAGES