servo/.github/workflows/docker.yml

name: Build Docker image and push to GitHub Packages

# This workflow file is adapted from the example at https://docs.github.com/en/packages/managing-github-packages-using-github-actions-workflows/publishing-and-installing-a-package-with-github-actions#upgrading-a-workflow-that-accesses-a-registry-using-a-personal-access-token
on:
  push:
    branches:
      - main
    # Only rebuild if the Dockerfile or dependencies change.
    paths: &container-paths
      - '.devcontainer/**'
      - 'python/servo/platform/linux_packages/**'
      - '.github/workflows/docker.yml'
  workflow_dispatch:
  pull_request:
    branches:
      - main
    paths: *container-paths

env:
  IMAGE_NAME: devcontainer-ubuntu
  IMAGE_DOWNLOAD_PATH: docker-image-artifacts
  # AMD64 and ARM64 label names are what docker chose
  AMD64_IMAGE_ARCHIVE: devcontainer-ubuntu-amd64.tar
  ARM64_IMAGE_ARCHIVE: devcontainer-ubuntu-arm64.tar
  AMD64_IMAGE_ARTIFACT_NAME: devcontainer-ubuntu-image-amd64
  ARM64_IMAGE_ARTIFACT_NAME: devcontainer-ubuntu-image-arm64

jobs:
  devcontainer_ubuntu_build:
    runs-on: ${{ matrix.runner }}
    strategy:
      fail-fast: false
      matrix:
        include:
          - arch: amd64
            platform: linux/amd64
            runner: ubuntu-24.04
            image_archive: devcontainer-ubuntu-amd64.tar
            image_artifact_name: devcontainer-ubuntu-image-amd64
          - arch: arm64
            platform: linux/arm64
            runner: ubuntu-24.04-arm
            image_archive: devcontainer-ubuntu-arm64.tar
            image_artifact_name: devcontainer-ubuntu-image-arm64
    permissions:
      contents: read
    steps:
      - uses: actions/checkout@v6

      - name: Build ${{ matrix.arch }} image
        run: |
          docker build . \
            --file .devcontainer/Ubuntu.Dockerfile \
            --platform ${{ matrix.platform }} \
            --tag ${{ env.IMAGE_NAME }}:${{ matrix.arch }} \
            --label "runnumber=${GITHUB_RUN_ID}"

      - name: Save ${{ matrix.arch }} image
        if: github.event_name != 'pull_request'
        run: docker save --output "${{ matrix.image_archive }}" "${{ env.IMAGE_NAME }}:${{ matrix.arch }}"

      - name: Upload ${{ matrix.arch }} image artifact
        if: github.event_name != 'pull_request'
        uses: actions/upload-artifact@v7
        with:
          name: ${{ matrix.image_artifact_name }}
          path: ${{ matrix.image_archive }}
          archive: false
          if-no-files-found: error

  devcontainer_ubuntu_publish:
    runs-on: ubuntu-24.04
    needs:
      - devcontainer_ubuntu_build
    # Use manual workflow dispatch in your fork to test changes.
    if: (github.event_name == 'push' && github.repository_owner == 'servo') || github.event_name == 'workflow_dispatch'
    permissions:
      contents: read
      packages: write
    steps:
      - uses: actions/download-artifact@v8
        with:
          path: ${{ env.IMAGE_DOWNLOAD_PATH }}
          merge-multiple: true

      - name: List downloaded image artifacts
        run: ls -R "${{ env.IMAGE_DOWNLOAD_PATH }}"

      - name: Derive image metadata
        id: image_meta
        run: |
          IMAGE_ID=ghcr.io/${{ github.repository_owner }}/servo/${{ env.IMAGE_NAME }}

          # This changes all uppercase characters to lowercase.
          IMAGE_ID=$(echo "$IMAGE_ID" | tr '[A-Z]' '[a-z]')
          # This strips the git ref prefix from the version.
          VERSION=$(echo "${{ github.ref }}" | sed -e 's,.*/\(.*\),\1,')

          # This uses the Docker `latest` tag convention.
          [ "$VERSION" = "main" ] && VERSION=latest
          
          echo "IMAGE_ID=$IMAGE_ID"
          echo "VERSION=$VERSION"

          echo "image_id=$IMAGE_ID" >> "$GITHUB_OUTPUT"
          echo "version=$VERSION" >> "$GITHUB_OUTPUT"
          echo "multiarch_tag=$IMAGE_ID:$VERSION" >> "$GITHUB_OUTPUT"

      - name: Log in to registry
        run: echo "${{ secrets.GITHUB_TOKEN }}" | docker login ghcr.io -u ${{ github.actor }} --password-stdin

      - name: Push platform images and publish manifest list
        run: |
          for archive in "${{ env.AMD64_IMAGE_ARCHIVE }}" "${{ env.ARM64_IMAGE_ARCHIVE }}"; do
            docker load --input "${{ env.IMAGE_DOWNLOAD_PATH }}/$archive"
          done

          IMAGE_TAGS=()

          for arch in amd64 arm64; do
            IMAGE=${{ steps.image_meta.outputs.image_id }}:$arch-${{ steps.image_meta.outputs.version }}
            IMAGE_TAGS+=("$IMAGE")
            docker tag ${{ env.IMAGE_NAME }}:$arch "$IMAGE"
            docker push "$IMAGE"
          done

          # This pushes to the registry
          docker buildx imagetools create --tag ${{ steps.image_meta.outputs.multiarch_tag }} "${IMAGE_TAGS[@]}"