docker-build.yml

name: Build and Push Docker Image

on:
  push:
    branches:
      - main
  release:
    types: [published, created]

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

permissions:
  contents: read
  packages: write

jobs:
  # Classify push so release-please-only merges can retag the last code image instead of rebuilding.
  changes:
    runs-on: ubuntu-latest
    outputs:
      build_code: ${{ steps.result.outputs.build_code }}
      release_bump: ${{ steps.result.outputs.release_bump }}
    steps:
      - name: Checkout repository
        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd

      - name: Paths filter (push to main only)
        if: github.event_name == 'push'
        uses: dorny/paths-filter@fbd0ab8f3e69293af611ebaee6363fc25e6d187d
        id: filter
        with:
          filters: |
            build_code:
              - 'src/**'
              - 'scripts/**'
              - 'Dockerfile'
            release_bump:
              - 'package.json'
              - 'CHANGELOG.md'

      - name: Emit change flags
        id: result
        run: |
          if [ "${{ github.event_name }}" = "release" ]; then
            echo "build_code=true" >> "$GITHUB_OUTPUT"
            echo "release_bump=false" >> "$GITHUB_OUTPUT"
          else
            echo "build_code=${{ steps.filter.outputs.build_code }}" >> "$GITHUB_OUTPUT"
            echo "release_bump=${{ steps.filter.outputs.release_bump }}" >> "$GITHUB_OUTPUT"
          fi

  build-and-push:
    needs: changes
    if: >-
      github.event_name == 'release'
      || (
        github.event_name == 'push'
        && needs.changes.outputs.build_code == 'true'
      )
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd

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

      - name: Log in to Container Registry
        uses: docker/login-action@c94ce9fb468520275223c153574b00df6fe4bcc9
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Extract metadata
        id: meta
        uses: docker/metadata-action@c299e40c65443455700f0fdfc63efafe5b349051
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          tags: |
            type=ref,event=branch
            type=ref,event=pr
            type=semver,pattern={{version}}
            type=semver,pattern={{major}}.{{minor}}
            type=semver,pattern={{major}}
            type=sha,prefix=sha-
            type=raw,value=latest,enable={{is_default_branch}}
            type=raw,value=main,enable={{is_default_branch}}
          flavor: |
            latest=auto
          labels: |
            org.opencontainers.image.title={{repo}}
            org.opencontainers.image.description={{description}}
            org.opencontainers.image.vendor={{vendor}}
            org.opencontainers.image.version={{version}}
            org.opencontainers.image.revision={{sha}}
            org.opencontainers.image.created={{created}}

      - name: Build and push Docker image
        uses: docker/build-push-action@10e90e3645eae34f1e60eeb005ba3a3d33f178e8
        with:
          context: .
          push: true
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          cache-from: type=gha
          cache-to: type=gha,mode=max

  # After release-please merges (version/changelog only), point semver + merge SHA tags at the
  # same image as the last commit that actually got a build (github.event.before may be a
  # release-only merge with no sha-* tag in GHCR — walk first-parent chain until crane finds one).
  retag-release-image:
    needs: changes
    if: >-
      github.event_name == 'push'
      && needs.changes.outputs.build_code != 'true'
      && needs.changes.outputs.release_bump == 'true'
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd
        with:
          fetch-depth: 0

      - name: Log in to Container Registry
        uses: docker/login-action@c94ce9fb468520275223c153574b00df6fe4bcc9
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Install crane
        env:
          CRANE_VERSION: v0.20.3
        run: |
          set -euo pipefail
          curl -sSL "https://github.com/google/go-containerregistry/releases/download/${CRANE_VERSION}/go-containerregistry_Linux_x86_64.tar.gz" \
            | sudo tar -xz -C /usr/local/bin crane
          crane version

      - name: Retag existing image with release version and merge SHA
        env:
          BEFORE_SHA: ${{ github.event.before }}
          MERGE_SHA: ${{ github.sha }}
        run: |
          set -euo pipefail
          if [ "$BEFORE_SHA" = "0000000000000000000000000000000000000000" ]; then
            echo "::error::github.event.before is empty; cannot locate the pre-merge image to retag."
            exit 1
          fi
          MERGE_TAG="sha-${MERGE_SHA:0:7}"
          VERSION="$(node -p "require('./package.json').version")"
          # Strip prerelease/build for x.y rolling tags (same idea as docker/metadata semver flavor)
          BASE="${VERSION%%-*}"
          MAJOR="${BASE%%.*}"
          REST="${BASE#*.}"
          MINOR="${REST%%.*}"

          IMAGE_LC="$(echo "${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}" | tr '[:upper:]' '[:lower:]')"

          # BEFORE_SHA often has no image (release-only / docs-only commits). Walk first-parent
          # chain until we find a sha-* tag that exists in GHCR (matches docker/metadata).
          CURRENT="$BEFORE_SHA"
          MAX_WALK=50
          SRC_REF=""
          for _ in $(seq 1 "$MAX_WALK"); do
            TAG="sha-${CURRENT:0:7}"
            REF="${IMAGE_LC}:${TAG}"
            if crane digest "$REF" >/dev/null 2>&1; then
              SRC_REF="$REF"
              echo "Using existing image tag $TAG (commit $CURRENT) as retag source."
              break
            fi
            echo "No image for $TAG, walking parent..."
            CURRENT="$(git rev-parse "${CURRENT}^" 2>/dev/null)" || break
          done
          if [ -z "$SRC_REF" ]; then
            echo "::error::No sha-* tag found in GHCR walking back up to $MAX_WALK commits from $BEFORE_SHA. Push a change that runs build-and-push on main, then retry the release merge."
            exit 1
          fi

          mapfile -t NEW_TAGS < <(printf '%s\n' \
            "$VERSION" \
            "${MAJOR}.${MINOR}" \
            "$MAJOR" \
            "$MERGE_TAG" \
            latest \
            main | awk 'NF && !seen[$0]++')

          for t in "${NEW_TAGS[@]}"; do
            echo "Tagging ${SRC_REF} -> ${IMAGE_LC}:${t}"
            crane copy "$SRC_REF" "${IMAGE_LC}:${t}"
          done

          echo "Retag complete for: ${NEW_TAGS[*]}"