docker-build.yaml

name: Docker Build
on: [ pull_request, push, workflow_dispatch ]
env:
  APP_NAME: petclinic
  APP_PORT: 8080

jobs:
  #####################################################################################################################
  ## The compile job compiles the application into a jar, and uploads it as an artifact for the next job to use.
  compile:
    name: Compile
    runs-on: ubuntu-20.04
    outputs:
      jarname: ${{ steps.get-jarname.outputs.jarname }}
      commit_sha: ${{ steps.commit-data.outputs.short_sha }}
    env:
      TARGET_DIR: target/
      MVN_REPO_DIR: ~/.m2/repository
    steps:
    - uses: actions/checkout@v2

    - name: Setup Java
      uses: actions/setup-java@v2
      with:
        distribution: temurin
        java-version: 11
        cache: maven

    - run: java -version

    - run: mvn -ntp -B package

    # Store the output jar into the env for reuse below.
    # It will contain, eg. "spring-petclinic-2.3.0.BUILD-SNAPSHOT.jar"
    - name: Get jar filename
      id: get-jarname
      run: |
        export JAR_NAME="$(basename $(ls target/*.jar))"
        echo "Petclinic jar is $JAR_NAME"
        echo "::set-output name=jarname::$JAR_NAME"
        echo "JAR_NAME=$JAR_NAME" >> $GITHUB_ENV

    # Upload the jar for future jobs to use.
    - uses: actions/upload-artifact@v2
      with:
        name: ${{ env.JAR_NAME }}
        path: ${{ env.TARGET_DIR }}/${{ env.JAR_NAME }}
        if-no-files-found: error

    # Use the commit short-sha as the suffix of the app_name
    - name: Get commit short-sha
      id: commit-data
      uses: redhat-actions/common/commit-data@v1

  #####################################################################################################################
  ## The build and push image job builds the container image with the petclinic jar in it,
  ## and pushes it to an image registry.
  ## It outputs the image tag and image URL for the next step to use when deploying to the OpenShift cluster.
  build-push-image:
    name: Docker Build
    runs-on: ubuntu-20.04
    needs: compile
    env:
      JAR_NAME: ${{ needs.compile.outputs.jarname }}
      IMAGE_TAGS: latest ${{ needs.compile.outputs.commit_sha }}
    steps:
      - uses: actions/checkout@v2

      # Download the jar artifact from the compile step
      - uses: actions/download-artifact@v2
        with:
          name: ${{ env.JAR_NAME }}

      # The dockerfile expects the jar to be under target/
      - name: Fake target/ dir
        run: |
          mkdir target/
          mv -v ${{ env.JAR_NAME }} target/

      # Use buildah to build the application image with the jar inside.
      - name: Build Image
        uses: redhat-actions/buildah-build@v2
        with:
          image: ${{ env.APP_NAME }}
          tags: ${{ env.IMAGE_TAGS }}
          dockerfiles: |
            ./Dockerfile
          build-args:
            jar_name=${{ env.JAR_NAME }}