name: Release image

on:
  push:
    tags:
      - "v*"
  workflow_dispatch:

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

jobs:
  publish:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write
      id-token: write
      attestations: write
    steps:
      - name: Checkout
        uses: actions/checkout@v7

      # The Dockerfile cross-compiles with Go's GOOS/GOARCH from $BUILDPLATFORM,
      # so no QEMU emulation is needed for the arm64 image.
      - name: Set up Buildx
        uses: docker/setup-buildx-action@v4

      - name: Log in to ${{ env.REGISTRY }}
        uses: docker/login-action@v4
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Derive tags and labels
        id: meta
        uses: docker/metadata-action@v6
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          # A semver tag v1.3.4 publishes 1.3.4, 1.3, 1 and latest.
          # A manual run from a branch publishes only that branch name, so
          # dispatching from main never moves the latest tag.
          tags: |
            type=semver,pattern={{version}}
            type=semver,pattern={{major}}.{{minor}}
            type=semver,pattern={{major}}
            type=ref,event=branch
          labels: |
            org.opencontainers.image.title=SkunkyArt
            org.opencontainers.image.description=An alternative frontend for DeviantArt that works entirely without JavaScript

      - name: Build and push
        id: build
        uses: docker/build-push-action@v7
        with:
          context: .
          platforms: linux/amd64,linux/arm64
          push: true
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          # Link the tag into the binary, so --help and /api/instance report the
          # same version as the image tag.
          build-args: |
            VERSION=${{ steps.meta.outputs.version }}
          cache-from: type=gha
          cache-to: type=gha,mode=max

      - name: Attest build provenance
        uses: actions/attest-build-provenance@v2
        with:
          subject-name: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          subject-digest: ${{ steps.build.outputs.digest }}
          push-to-registry: true