docker-multiarch.yml

name: Docker Multi-Arch Build

on:
  push:
    branches: [ "main" ]
    tags: [ 'v*.*.*' ]  # build when you push a release tag
  pull_request:
    branches: [ "main" ]

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

jobs:
  build-multiarch:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write
      id-token: write
    steps:
      - name: Checkout repository
        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: Log into registry ${{ env.REGISTRY }}
        if: github.event_name != 'pull_request'
        uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      # Generate tags:
      # - on main: :main (no latest here, see flavor=latest=false)
      # - on vX.Y.Z tags: :vX.Y.Z, :vX.Y, :vX and (optionally) :latest
      - name: Extract Docker metadata
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          flavor: |
            latest=false
          tags: |
            # tag event → semver tags
            type=ref,event=tag
            type=semver,pattern={{version}}
            type=semver,pattern={{major}}.{{minor}}
            type=semver,pattern={{major}}
            # branch/SHA tags (for main/PRs)
            type=ref,event=branch
            type=sha

      - name: Build and push multi-arch Docker image
        uses: docker/build-push-action@v5
        with:
          context: .
          push: ${{ github.event_name != 'pull_request' }}
          platforms: linux/amd64,linux/arm64
          # Always push the meta-generated tags.
          # Also push :latest only on semver tag builds (release).
          tags: |
            ${{ steps.meta.outputs.tags }}
            ${{ github.ref_type == 'tag' && startsWith(github.ref_name, 'v') && format('{0}/{1}:latest', env.REGISTRY, env.IMAGE_NAME) || '' }}
          labels: ${{ steps.meta.outputs.labels }}
          cache-from: type=gha
          cache-to: type=gha,mode=max