build-image.yml

name: Build the target Docker image

on:
  workflow_call:
    inputs:
      image_name:
        required: true
        type: string 
        description: Image name without tag, e.g. 'repo/app'
      image_tag_suffix:
        required: true
        type: string
        default: ''
      target_env:
        required: true
        type: string
        default: 'production'
        # options:
        # - production
        # - dev
      settings_module:
        required: true
        type: string
        default: 'docker'
        # options:
        # - docker
        # - dev
    outputs:
      image_name:
        description: Image name + tag of the built image
        value: ${{ jobs.image_build.outputs.image_name }}
      artifact_name:
        description: Artifact name for the built image
        value: ${{ jobs.image_build.outputs.artifact_name }}

jobs:
  image_build:
    name: Build image
    runs-on: ubuntu-latest

    env:
      COMPOSE_DOCKER_CLI_BUILD: 1
      DOCKER_BUILDKIT: 1

    outputs:
      image_name: ${{ steps.build-args.outputs.image_name }}
      artifact_name: ${{ steps.build-args.outputs.artifact_name }}

    steps:
      - uses: actions/checkout@v4

      - name: Extract build args
        id: build-args
        run: |
          # Strip git ref prefix from version
          VERSION=$(echo "${{ github.ref }}" | sed -e 's,.*/\(.*\),\1,')

          # Use Docker `latest` tag convention
          [ "$VERSION" == "main" ] && VERSION=latest

          # PRs result in version 'merge' -> transform that into 'latest'
          [ "$VERSION" == "merge" ] && VERSION=latest

          echo "version=${VERSION}" >> $GITHUB_OUTPUT
          echo "image_name=${{ inputs.image_name }}:${VERSION}${{ inputs.image_tag_suffix }}" >> $GITHUB_OUTPUT
          echo "artifact_name=docker-image-${VERSION}${{ inputs.image_tag_suffix }}" >> $GITHUB_OUTPUT
          echo "git_hash=${GITHUB_SHA}" >> $GITHUB_OUTPUT

      - name: Build the Docker image
        run: |
          docker build . \
            --tag ${{ steps.build-args.outputs.image_name }} \
            --build-arg COMMIT_HASH=${{ steps.build-args.outputs.git_hash }} \
            --build-arg RELEASE=${{ steps.build-args.outputs.version }} \
            --build-arg TARGET_ENVIRONMENT=${{ inputs.target_env }} \
            --build-arg SETTINGS_MODULE=${{ inputs.settings_module }}

      - name: Dump image to file
        run: docker image save -o image.tar ${{ steps.build-args.outputs.image_name }}

      - name: Store image artifact
        uses: actions/upload-artifact@v4
        with:
          name: ${{ steps.build-args.outputs.artifact_name }}
          path: image.tar
          retention-days: 1