.github/workflows/deploy-site.yml

# Builds and deploys the site if the build was successful
#
# This job builds the website and deploys the build artifacts to the 'content' directory
# Any additional files that are not part of the site build but should be published (e.g. website configuration files) must be handled explicitly
# See step "Move additional resources to build directory" and sub-steps "Dropping old site resources" and "Adding new site configuration" of the 'publish' step
name: Build & Deploy Site

# Conditions necessary to trigger a build
on:
  push:
    # Ignore pushes on all branches by default
    # Branches that should trigger a build must be explicitly excluded from the ignore using '!BRANCH_NAME'
    #
    # Excluding the branch that is pushed by this action will lead to an infinite loop
    branches-ignore:
      - '**'
      - '!master'

    # Only build if a file in one of these paths has been changed
    paths:
      - 'src/main/asciidoc/**'
      - 'src/main/template/**'
      - '.asf.yaml.publish'
      - '.htaccess'


jobs:
  build:
    name: Build & Deploy Site
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v2
        with:
          fetch-depth: 1


      - name: Build Site
        run: mvn clean compile


      # Determines the short sha of the commit that triggered the build
      - name: Determine Short SHA
        if: success()
        id: short-sha
        run: |
          short_sha=$(git rev-parse --short=10 $GITHUB_SHA)
          echo "::set-output name=short_sha::$short_sha"
        shell: 'bash'


      # Determines the author data of the HEAD commit
      # Sets up the author data to be used for the site deploy commit
      - name: Determine HEAD Commit Author Data
        if: success()
        id: author-data
        run: |
          echo "Reading author data"
          author_name=$(git log -1 --format='%aN' HEAD)
          author_email=$(git log -1 --format='%aE' HEAD)

          echo "Setting up author data to use for deploy commit"
          git config user.name $author_name
          git config user.email $author_email
        shell: 'bash'


      # Adds additional configuration files that are supposed to be included in the page deploy to the build directory
      #
      # This ensures that such files are preserved when checking out the publish branch
      - name: Add additional resources to build directory
        if: success()
        run: |
          cp -v .asf.yaml.publish target/site/.asf.yaml
          cp -v .htaccess target/site/


      # Publishes the site build results to a separate branch
      #
      # Checks out the site branch
      # Replaces the site configuration files and site build artifact with the ones set up in the previous step
      # Creates a new commit containing the new site build artifacts and site configuration files
      # The commit is created with the author data set up in the previous step
      # Pushes the site branch
      - name: Publish site branch
        if: success()
        run: |
          branch_name="publish"

          echo "Checking out site branch"
          git fetch origin $branch_name
          git checkout -b $branch_name origin/$branch_name
          echo

          # Drops all existing files and folders except the base folder and the resources excluded by the regex
          # This ensures that old configuration files that were removed on the master will be removed from the site branch as well
          # Additional resources to exclude can be added by modifying the regex or adding new regex by using "-a -not -regex '...'"
          echo "Dropping old site resources"
          find . \
            -mindepth 1 -regextype posix-extended \
            -not -regex '^\./(target|.git)(/.*)?$' \
            -delete -print
          echo

          echo "Adding new site configuration"
          mv -v target/site/.asf.yaml ./
          mv -v target/site/.htaccess ./
          echo

          echo "Adding new site build"
          mkdir -v content
          mv -v target/site/* content/
          echo

          # Explicitly removes build dir
          # This checks whether there are any remaining resources that were not moved to the correct location
          echo "Removing build dir"
          rmdir -v -p target/site
          echo

          echo "Staging new content"
          git add .
          echo

          echo "Committing changes"
          git commit -m "Auto-deploy site for commit ${{ steps.short-sha.outputs.short_sha }}"
          echo

          echo "Pushing site branch"
          git push origin $branch_name
        shell: 'bash'