DockerPublish.yml

# Based on
# <https://docs.github.com/en/actions/publishing-packages/publishing-docker-images>
# <https://docs.docker.com/build/ci/github-actions/multi-platform/#distribute-build-across-multiple-runners>.

name: Publish Docker image

on:
  workflow_dispatch:
  push:
    branches: [ "main" ]
    # Publish semver tags as releases.
    tags: [ 'v*.*.*' ]
    paths:
      - '.github/workflows/DockerPublish.yml'
      - 'Dockerfile'
      - 'Project.toml'
      - 'julia_cpu_target.sh'
      - '**/*.jl'
  pull_request:
    branches: [ "main" ]
    paths:
      - '.github/workflows/DockerPublish.yml'
      - 'Dockerfile'
      - 'Project.toml'
      - 'julia_cpu_target.sh'
      - '**/*.jl'

env:
  REGISTRY: ghcr.io
  IMAGE_NAME: ${{ github.repository }}

concurrency:
  # Skip intermediate builds: always.
  # Cancel intermediate builds: only if it is a pull request build.
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: ${{ startsWith(github.ref, 'refs/pull/') }}

jobs:

  build:

    strategy:
      fail-fast: false
      matrix:
        include:
          - platform: 'linux/amd64'
            os: 'ubuntu-latest'
          - platform: 'linux/arm64'
            os: 'ubuntu-24.04-arm'

    runs-on: ${{ matrix.os }}
    permissions:
      contents: read
      packages: write
      attestations: write
      # This is used to complete the identity challenge
      # with sigstore/fulcio when running outside of PRs.
      id-token: write

    steps:

      - name: Checkout repository
        uses: actions/checkout@v4

      - name: Prepare
        run: |
          platform=${{ matrix.platform }}
          echo "PLATFORM_PAIR=${platform//\//-}" >> "${GITHUB_ENV}"

      # Docker is terrible and doesn't like uppercase image names.
      - name: Lowercase image name
        run: |
          IMAGE_NAME=$(echo ${IMAGE_NAME} | tr A-Z a-z)
          echo "IMAGE_NAME=${IMAGE_NAME}" >> "${GITHUB_ENV}"

      # Needed to make caching on GHA work: https://stackoverflow.com/a/73884678.
      # https://github.com/docker/setup-buildx-action
      - name: Setup Docker buildx
        uses: docker/setup-buildx-action@v3

      # Log into the registry except on PRs.
      # https://github.com/docker/login-action
      - name: Log into registry ${{ env.REGISTRY }}
        if: github.event_name != 'pull_request'
        uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      # Extract metadata (tags, labels) for Docker
      # https://github.com/docker/metadata-action
      - name: Extract Docker metadata
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}

      # Build and push Docker image with Buildx (don't push on PR)
      # https://github.com/docker/build-push-action
      - name: Build and push by digest
        id: build
        uses: docker/build-push-action@v6
        with:
          context: .
          push: ${{ github.event_name != 'pull_request' }}
          platforms: ${{ matrix.platform }}
          labels: ${{ steps.meta.outputs.labels }}
          outputs: type=image,name=${{ env.REGISTRY }}/${{ env.IMAGE_NAME }},push-by-digest=true,name-canonical=true,push=${{ github.event_name != 'pull_request' }}
          tags: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          # See: https://docs.docker.com/build/ci/github-actions/cache/#github-cache
          cache-from: type=gha
          cache-to: type=gha,mode=max

      - name: Export digest
        run: |
          mkdir -p /tmp/digests
          digest="${{ steps.build.outputs.digest }}"
          touch "/tmp/digests/${digest#sha256:}"

      - name: Upload digest
        uses: actions/upload-artifact@v4
        with:
          name: digests-${{ env.PLATFORM_PAIR }}
          path: /tmp/digests/*
          if-no-files-found: error
          retention-days: 1

  merge:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write
      attestations: write
      # This is used to complete the identity challenge
      # with sigstore/fulcio when running outside of PRs.
      id-token: write
    if: github.event_name != 'pull_request'
    needs:
      - build
    steps:

      # Docker is terrible and doesn't like uppercase image names.
      - name: Lowercase image name
        run: |
          IMAGE_NAME=$(echo ${IMAGE_NAME} | tr A-Z a-z)
          echo "IMAGE_NAME=${IMAGE_NAME}" >> "${GITHUB_ENV}"

      - name: Download digests
        uses: actions/download-artifact@v4
        with:
          path: /tmp/digests
          pattern: digests-*
          merge-multiple: true

      # https://github.com/docker/setup-buildx-action
      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      # Extract metadata (tags, labels) for Docker
      # https://github.com/docker/metadata-action
      - name: Docker meta
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          tags: |
            type=ref,event=branch
            type=ref,event=pr
            type=semver,pattern={{version}}
            type=semver,pattern={{major}}.{{minor}}

      # Log into the registry.
      # https://github.com/docker/login-action
      - name: Log into registry ${{ env.REGISTRY }}
        uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Create manifest list and push
        working-directory: /tmp/digests
        run: |
          docker buildx imagetools create $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "${DOCKER_METADATA_OUTPUT_JSON}") \
            $(printf '${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}@sha256:%s ' *)

      - name: Inspect image
        run: |
          docker buildx imagetools inspect ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ steps.meta.outputs.version }}