name: Publish Container Image

# Builds and publishes the Backspace application image to the GitHub Container
# Registry (GHCR) as a multi-architecture (linux/amd64 + linux/arm64) image, so
# self-hosters — including weak/ARM boxes like a Raspberry Pi — can `docker pull`
# a prebuilt image instead of building the ~1.6 GB image locally (the Vite build
# OOMs small ARM hosts). install.sh and docker-compose.yml default to pulling
# this image, with a from-source build as the fallback.
#
# This is intentionally SEPARATE from the desktop-installer workflow
# (release.yml) — they share the `v*` tag trigger but build entirely different
# artifacts and must not be entangled.

on:
  push:
    tags:
      - 'v*'
  # Allow a manual rebuild/publish (e.g. to (re)publish `latest` or a moving tag
  # without cutting a new release).
  workflow_dispatch:
    inputs:
      tag:
        description: 'Extra tag to publish (optional, e.g. "edge")'
        required: false
        default: ''

permissions:
  contents: read
  packages: write
  security-events: write

jobs:
  build-and-push:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5.0.1

      # The runtime image bakes the git commit for the AGPL-3.0 § 13 source
      # offer (config.commit → GET /api/instance/info). The .git dir is not in
      # the build context (.dockerignore), so resolve the short SHA here and feed
      # it to the build as a --build-arg, matching install.sh / deploy.sh.
      - name: Resolve build metadata
        id: meta_commit
        run: echo "commit=$(git rev-parse --short HEAD)" >> "$GITHUB_OUTPUT"

      - name: Set up QEMU
        uses: docker/setup-qemu-action@c7c53464625b32c7a7e944ae62b3e17d2b600130 # v3.7.0

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f # v3.12.0

      - name: Log in to GitHub Container Registry
        uses: docker/login-action@c94ce9fb468520275223c153574b00df6fe4bcc9 # v3.7.0
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Derive image tags and labels
        id: docker_meta
        uses: docker/metadata-action@c299e40c65443455700f0fdfc63efafe5b349051 # v5.10.0
        with:
          # github.repository is "TheZwiss/backspace"; metadata-action lowercases
          # it → ghcr.io/thezwiss/backspace (GHCR requires lowercase).
          images: ghcr.io/${{ github.repository }}
          tags: |
            type=semver,pattern={{version}}
            type=semver,pattern={{major}}.{{minor}}
            type=raw,value=latest,enable=${{ startsWith(github.ref, 'refs/tags/v') }}
            type=sha
            type=raw,value=${{ github.event.inputs.tag }},enable=${{ github.event.inputs.tag != '' }}
          labels: |
            org.opencontainers.image.title=Backspace
            org.opencontainers.image.description=Self-hosted Discord alternative — text, voice, video, and federation.
            org.opencontainers.image.source=https://github.com/TheZwiss/backspace
            org.opencontainers.image.licenses=AGPL-3.0-only
            org.opencontainers.image.revision=${{ github.sha }}

      # Build a single-arch amd64 image and LOAD it into the runner's docker
      # daemon so Trivy can scan the exact artifact before anything is published.
      # A multi-arch manifest cannot be --load'ed, so scanning must happen on a
      # single-arch build first; the multi-arch push below reuses these layers
      # from the buildx cache, so this is cheap.
      - name: Build amd64 image for scanning
        uses: docker/build-push-action@10e90e3645eae34f1e60eeb005ba3a3d33f178e8 # v6.19.2
        with:
          context: .
          platforms: linux/amd64
          load: true
          push: false
          tags: backspace:scan
          build-args: |
            BACKSPACE_COMMIT=${{ steps.meta_commit.outputs.commit }}
          cache-from: type=gha
          cache-to: type=gha,mode=max

      - name: Trivy image scan (report-only)
        uses: aquasecurity/trivy-action@ed142fd0673e97e23eac54620cfb913e5ce36c25 # v0.36.0
        continue-on-error: true # report-only; enforcement flipped on in Plan E
        with:
          scan-type: image
          image-ref: backspace:scan
          ignore-unfixed: true
          format: sarif
          output: trivy-image.sarif
          severity: HIGH,CRITICAL

      - name: Upload Trivy image SARIF
        if: always()
        continue-on-error: true # a scanner/SARIF-emit flake must never skip the publish below
        uses: github/codeql-action/upload-sarif@02c5e83432fe5497fd85b873b6c9f16a8578e1d9 # v3.37.0
        with:
          sarif_file: trivy-image.sarif
          category: trivy-image

      # Publish the multi-arch image. Reuses the amd64 layers built above via the
      # gha cache. Attaches an SBOM and SLSA provenance attestation to the image.
      - name: Build and push (linux/amd64, linux/arm64)
        uses: docker/build-push-action@10e90e3645eae34f1e60eeb005ba3a3d33f178e8 # v6.19.2
        with:
          context: .
          platforms: linux/amd64,linux/arm64
          push: true
          tags: ${{ steps.docker_meta.outputs.tags }}
          labels: ${{ steps.docker_meta.outputs.labels }}
          build-args: |
            BACKSPACE_COMMIT=${{ steps.meta_commit.outputs.commit }}
          sbom: true
          provenance: true
          # Cache multi-arch layers across runs via the GitHub Actions cache to
          # keep the ~1.6 GB build from re-running cold every release.
          cache-from: type=gha
          cache-to: type=gha,mode=max