build-contributor-container-PR.yml

name: 'Build Contributor container (PR)'
# For speedup to do this in parallel: https://docs.docker.com/build/ci/github-actions/multi-platform/
# Loosely based on: https://docs.docker.com/build/ci/github-actions/push-multi-registries/

on:
  push:
  pull_request_target:
    branches:
      - main

jobs:
  pr-contributor:
    if: ${{ !(github.repository == 'domjudge/domjudge-packaging' &&
              github.ref == 'refs/heads/main') &&
            !contains(github.ref, 'gh-readonly-queue') &&
            (github.event_name == 'pull_request_target' ||
             github.event.pull_request.head.repo.full_name != github.repository) }}
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4
      - name: Set up QEMU
        uses: docker/setup-qemu-action@v3
      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3
      - name: Login to GitHub container registry
        uses: docker/login-action@v3
        with:
          registry: ghcr.io
          username: ${{ github.repository_owner }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Extract metadata (tags, labels) for Docker
        id: meta
        uses: docker/metadata-action@9ec57ed1fcdbf14dcef7dfbe97b2010124a938b7
        with:
          images: ghcr.io/${{ github.repository }}

      - name: Build and push
        uses: docker/build-push-action@v5
        with:
          context: docker-contributor
          platforms: linux/amd64,linux/arm64
          push: true
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}