synapse/.github/workflows/docker.yml

# GitHub actions workflow which builds and publishes the docker images.

name: Build docker images

on:
  push:
    tags: ["v*"]
    branches: [ master, main, develop ]
  workflow_dispatch:

permissions:
  contents: read

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Set up QEMU
        id: qemu
        uses: docker/setup-qemu-action@v1
        with:
          platforms: arm64

      - name: Set up Docker Buildx
        id: buildx
        uses: docker/setup-buildx-action@v1

      - name: Inspect builder
        run: docker buildx inspect
          
      - name: Log in to DockerHub
        uses: docker/login-action@v1
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}

      - name: Calculate docker image tag
        id: set-tag
        run: |
          case "${GITHUB_REF}" in
              refs/heads/develop)
                  tag=develop
                  ;;
              refs/heads/master|refs/heads/main)
                  tag=latest
                  ;;
              refs/tags/*)
                  tag=${GITHUB_REF#refs/tags/}
                  ;;
              *)
                  tag=${GITHUB_SHA}
                  ;;
          esac
          echo "::set-output name=tag::$tag"          

        # for release builds, we want to get the amd64 image out asap, so first
        # we do an amd64-only build, before following up with a multiarch build.
      - name: Build and push amd64
        uses: docker/build-push-action@v2
        if: "${{ startsWith(github.ref, 'refs/tags/v') }}"
        with:
          push: true
          labels: "gitsha1=${{ github.sha }}"
          tags: "matrixdotorg/synapse:${{ steps.set-tag.outputs.tag }}"
          file: "docker/Dockerfile"
          platforms: linux/amd64

      - name: Build and push all platforms
        uses: docker/build-push-action@v2
        with:
          push: true
          labels: "gitsha1=${{ github.sha }}"
          tags: "matrixdotorg/synapse:${{ steps.set-tag.outputs.tag }}"
          file: "docker/Dockerfile"
          platforms: linux/amd64,linux/arm64