_docker.yml

name: Reusable Docker build & publish

# Reusable multi-arch build. Each architecture is built on its NATIVE runner
# (no QEMU emulation) in parallel, pushed by digest; a final job assembles the
# manifest list. Tags are derived from the caller's ref by metadata-action, so
# the same logic serves branch pushes (CI) and version tags (release).
on:
  workflow_call:

env:
  IMAGE: docker.io/softwarity/plug

jobs:
  build:
    name: Build ${{ matrix.platform }}
    runs-on: ${{ matrix.platform == 'linux/arm64' && 'ubuntu-24.04-arm' || 'ubuntu-latest' }}
    strategy:
      fail-fast: false
      matrix:
        platform: [linux/amd64, linux/arm64]
    steps:
      - uses: actions/checkout@v6
      - name: Prepare platform name
        run: echo "PLATFORM_PAIR=${platform//\//-}" >> "$GITHUB_ENV"
        env:
          platform: ${{ matrix.platform }}
      - name: Docker labels
        id: meta
        uses: docker/metadata-action@v6
        with:
          images: ${{ env.IMAGE }}
      - uses: docker/setup-buildx-action@v4
      - name: Log in to Docker Hub
        uses: docker/login-action@v4
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_RW }}
      - name: Resolve version
        id: ver
        # A v-tag → its semver; any branch → "dev". The short commit is appended
        # as build metadata (Dockerfile) so every rebuild — even the same
        # `latest` tag — is distinct and the CLI picks up the new core.
        run: |
          ref="${GITHUB_REF#refs/tags/v}"
          case "$GITHUB_REF" in
            refs/tags/v*) echo "value=$ref" >> "$GITHUB_OUTPUT" ;;
            *)            echo "value=dev"   >> "$GITHUB_OUTPUT" ;;
          esac
          echo "rev=${GITHUB_SHA::7}" >> "$GITHUB_OUTPUT"
      - name: Build and push by digest
        id: build
        uses: docker/build-push-action@v7
        with:
          context: .
          file: agent/Dockerfile
          build-args: |
            VERSION=${{ steps.ver.outputs.value }}
            GIT_REV=${{ steps.ver.outputs.rev }}
          platforms: ${{ matrix.platform }}
          labels: ${{ steps.meta.outputs.labels }}
          outputs: type=image,name=${{ env.IMAGE }},push-by-digest=true,name-canonical=true,push=true
          cache-from: type=gha,scope=${{ env.PLATFORM_PAIR }}
          cache-to: type=gha,mode=max,scope=${{ env.PLATFORM_PAIR }}
      - name: Export digest
        run: |
          mkdir -p "${{ runner.temp }}/digests"
          digest="${{ steps.build.outputs.digest }}"
          touch "${{ runner.temp }}/digests/${digest#sha256:}"
      - name: Upload digest
        uses: actions/upload-artifact@v7
        with:
          name: digests-${{ env.PLATFORM_PAIR }}
          path: ${{ runner.temp }}/digests/*
          if-no-files-found: error
          retention-days: 1

  merge:
    name: Merge manifest list
    runs-on: ubuntu-latest
    needs: build
    steps:
      - name: Download digests
        uses: actions/download-artifact@v7
        with:
          path: ${{ runner.temp }}/digests
          pattern: digests-*
          merge-multiple: true
      - uses: docker/setup-buildx-action@v4
      - name: Docker tags
        id: meta
        uses: docker/metadata-action@v6
        with:
          images: ${{ env.IMAGE }}
          tags: |
            type=ref,event=branch
            type=raw,value=latest,enable={{is_default_branch}}
            type=semver,pattern={{version}}
            type=semver,pattern={{major}}.{{minor}}
      - name: Log in to Docker Hub
        uses: docker/login-action@v4
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_RW }}
      - name: Create and push manifest list
        working-directory: ${{ runner.temp }}/digests
        run: |
          docker buildx imagetools create \
            $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
            $(printf '${{ env.IMAGE }}@sha256:%s ' *)
      - name: Inspect
        run: docker buildx imagetools inspect "${{ env.IMAGE }}:${{ steps.meta.outputs.version }}"