name: Docker Hub

on:
  release:
    types: [published]

env:
  # Use docker.io for Docker Hub if empty
  REGISTRY: docker.io
  # github.repository as <account>/<repo>
  IMAGE_NAME: ${{ github.repository }}

jobs:
  build:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write

    steps:
      - name: Checkout repository
        uses: actions/checkout@v2
      # QEMU for emulation
      - name: Set up QEMU
        uses: docker/setup-qemu-action@v1
      # Docker Buildx for creating multi arch docker images
      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1

      # Login against a Docker registry when not a PR
      # https://github.com/docker/login-action
      - name: Log into registry ${{ env.REGISTRY }}
        if: github.event_name != 'pull_request'
        uses: docker/login-action@v1
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}

      # Extract metadata (tags, labels) for Docker
      # https://github.com/docker/metadata-action
      - name: Extract Docker metadata
        id: meta
        uses: docker/metadata-action@v3
        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 Docker image
        uses: docker/build-push-action@v2
        with:
          context: .
          platforms: linux/amd64,linux/arm64,linux/arm/v7
          push: ${{ github.event_name != 'pull_request' }}
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}

      - name: Image digest
        run: echo ${{ steps.docker_build.outputs.digest }}