name: Release

# Tagging is the release trigger: semver tags only, so a stray tag does not publish.
on:
  push:
    tags: ["v[0-9]+.[0-9]+.[0-9]+*"]

permissions:
  contents: read
  packages: write

jobs:
  image:
    name: Build and publish image
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: docker/setup-qemu-action@v3
      - uses: docker/setup-buildx-action@v3

      - uses: docker/login-action@v3
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - id: meta
        uses: docker/metadata-action@v5
        with:
          images: ghcr.io/${{ github.repository }}
          # v1.4.2 publishes 1.4.2, 1.4 and 1 — so a Rune pinned to :1 gets
          # patches without ever crossing a major version.
          tags: |
            type=semver,pattern={{version}}
            type=semver,pattern={{major}}.{{minor}}
            type=semver,pattern={{major}}
            type=raw,value=latest

      # arm64 is not optional: a homelab is as likely to be a Raspberry Pi or an
      # Apple silicon VM as it is to be an x86 box.
      - uses: docker/build-push-action@v6
        with:
          context: .
          platforms: linux/amd64,linux/arm64
          push: true
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          build-args: |
            VERSION=${{ github.ref_name }}
          cache-from: type=gha
          cache-to: type=gha,mode=max