name: Build docker image

permissions:
  contents: read

on:
  release:
    types:
      - published
  push:
    branches:
      - master
  # Allow maintainers to build/validate the multi-arch image on demand
  # (e.g. from a feature branch) without pushing anything to the registry.
  workflow_dispatch:

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

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

    steps:
      - name: Checkout repository
        uses: actions/checkout@v5

      - name: Set up QEMU
        uses: docker/setup-qemu-action@v3

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      - name: Docker meta
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: |
            ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          # generate Docker tags based on the following events/attributes
          tags: |
            type=ref,event=branch
            type=ref,event=pr
            type=semver,pattern={{version}}
            type=semver,pattern={{major}}.{{minor}}

      - name: Log in to the Container registry
        # Only authenticate when we will actually push (release). The master
        # push and workflow_dispatch runs build for validation only and must
        # never touch the registry, so they skip the login entirely.
        if: github.event_name == 'release'
        uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Build and push Docker image
        uses: docker/build-push-action@v6
        with:
          context: .
          platforms: linux/amd64,linux/arm64
          # Push only on a published release. Every other trigger (push to
          # master, workflow_dispatch) builds both architectures for
          # validation but never pushes.
          push: ${{ github.event_name == 'release' }}
          tags:  ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}