name: "Docker Build"

# Controls when the action will run. 
on:
  # Triggers the workflow on push or pull request events but only for the master branch
  workflow_dispatch: ~
  push:
    branches: [ master ]

jobs:
  build:
    runs-on: ubuntu-latest
    name: docker build and publish
    env:
      DOCKER_BUILDKIT: 1
      DOCKER_CLI_EXPERIMENTAL: enabled
      DOCKER_USERNAME: ${{ secrets.DOCKER_USERNAME }}
      DOCKERHUB_REPOSITORY: ${{ secrets.DOCKER_REPO }}
    steps:
      - name: Checkout
        uses: actions/checkout@v2

      - name: Login to DockerHub
        uses: docker/login-action@v1
        with:
          username: ${{ secrets.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_TOKEN }}

      - name: Setup Docker Buildx
        uses: crazy-max/ghaction-docker-buildx@v3

      - name: Buildx cache
        uses: actions/cache@v2
        id: buildx-cache
        with:
          path: /tmp/.buildx-cache
          key: ${{ runner.os }}-buildx

      - name: Build
        run: |
          declare -a IMAGES

          echo "Build amd64"
          docker buildx build \
            --cache-from "type=local,src=/tmp/.buildx-cache" \
            --cache-to "type=local,dest=/tmp/.buildx-cache" \
            --output "type=image,push=true" \
            --platform linux/amd64 \
            --build-arg "S6_ARCH=amd64" \
            --tag "${DOCKERHUB_REPOSITORY}:latest-amd64" \
            -f Dockerfile \
            .
          IMAGES+=( "${DOCKERHUB_REPOSITORY}:latest-amd64" )
          
          echo "Build arm64-v8"
          docker buildx build \
            --cache-from "type=local,src=/tmp/.buildx-cache" \
            --cache-to "type=local,dest=/tmp/.buildx-cache" \
            --output "type=image,push=true" \
            --platform linux/arm64/v8 \
            --build-arg "S6_ARCH=aarch64" \
            --tag "${DOCKERHUB_REPOSITORY}:latest-arm64-v8" \
            -f Dockerfile \
            .
          IMAGES+=( "${DOCKERHUB_REPOSITORY}:latest-arm64-v8" )
          
          echo "Create manifest lists"
          docker manifest create "${DOCKERHUB_REPOSITORY}:latest" "${IMAGES[@]}"

          echo "Annotate manifest lists to add architecture variants that aren't picked up automatically"
          docker manifest annotate "${DOCKERHUB_REPOSITORY}:latest" "${DOCKERHUB_REPOSITORY}:latest-arm64-v8" --variant "v8"

          echo "Push manifest lists & delete local copies"
          docker manifest push --purge "${DOCKERHUB_REPOSITORY}:latest"