build_container.yml

---
# Reusable workflow: build one container image from build/Dockerfiles/ and
# optionally push it to ghcr.io. Called by build_containers.yml (manual,
# single image) and containers.yml (PR validation + push/schedule publish).
name: 'Reusable: build container image'

on:
  workflow_call:
    inputs:
      dockerfile:
        description: "Dockerfile filename under build/Dockerfiles/"
        required: true
        type: string
      image_name:
        description: "Image name to publish under ghcr.io/<owner>/"
        required: true
        type: string
      ruby_version:
        description: "Default Ruby version build arg (ignored by Beaker images)"
        required: false
        type: string
        default: "3.2"
      ref:
        description: "Branch, tag, or SHA to build from"
        required: false
        type: string
        default: ""
      push:
        description: "Push the image to ghcr.io (false = build only, for PRs)"
        required: false
        type: boolean
        default: false
      extra_tag:
        description: "Optional additional tag (in addition to latest + date)"
        required: false
        type: string
        default: ""

permissions:
  contents: read
  packages: write

jobs:
  build:
    name: "${{ inputs.image_name }}"
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v7
        with:
          ref: ${{ inputs.ref }}

      - name: Compute image tags
        id: meta
        env:
          IMAGE: "ghcr.io/${{ github.repository_owner }}/${{ inputs.image_name }}"
          EXTRA_TAG: ${{ inputs.extra_tag }}
        run: |
          # Date-based tag (UTC) so it is clear when an image was built.
          date_tag="$(date -u +%Y%m%d)"
          tags="${IMAGE}:${date_tag},${IMAGE}:latest"
          if [ -n "$EXTRA_TAG" ]; then
            tags="${tags},${IMAGE}:${EXTRA_TAG}"
          fi
          echo "tags=${tags}" >> "$GITHUB_OUTPUT"
          echo "Image tags: ${tags}"

      - name: Log in to GitHub Container Registry
        if: ${{ inputs.push }}
        uses: docker/login-action@v4
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Build${{ inputs.push && ' and push' || ' (no push)' }}
        env:
          DOCKERFILE: ${{ inputs.dockerfile }}
          RUBY_VERSION: ${{ inputs.ruby_version }}
          TAGS: ${{ steps.meta.outputs.tags }}
          PUSH: ${{ inputs.push }}
        run: |
          cd build/Dockerfiles
          IFS=',' read -ra image_tags <<< "$TAGS"
          tag_args=()
          for t in "${image_tags[@]}"; do
            tag_args+=( -t "$t" )
          done
          docker build --pull \
            --build-arg ruby_version="$RUBY_VERSION" \
            -f "$DOCKERFILE" \
            "${tag_args[@]}" .
          if [ "$PUSH" = "true" ]; then
            for t in "${image_tags[@]}"; do
              docker push "$t"
            done
          fi