build_and_deploy.yml

---
name: Build and Deploy
on:
  push:
    branches:
      - main

jobs:

  define_images:
    # Define a build matrix based on all changed *.hcl files so we can run packer only for image definitions that have actually changed
    # So if e.g. ubuntu/focal/variables.auto.pkrvars.hcl or ubuntu/focal/src-ubuntu.pkr.hcl changes, add "ubuntu/focal" to the matrix
    # Also ensure that if an image template (for instance, the general template for ubuntu images 'ubuntu/src-ubuntu.pkr.hcl') changes,
    # an entry is added to the matrix for each image definition that relies on (i.e. symlinks) it.
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          path: "${{ github.repository }}"
      - name: Get changed image definitions
        # Find changed .hcl files in all <os>/<version> directories
        id: changed-images-yaml
        uses: tj-actions/changed-files@v39
        with:
          path: "${{ github.repository }}"
          dir_names: true
          dir_names_max_depth: 3
          quotepath: false
          files_yaml: |
            images:
              - '*/*/*.hcl'
      - name: Get changed image definition templates
        # Find all changed base templates in all <os>/ directories
        id: changed-symlink-yaml
        uses: tj-actions/changed-files@v39
        with:
          path: "${{ github.repository }}"
          quotepath: false
          files_yaml: |
            symlinks:
              - '*/*.hcl'
      - name: Get image directories based on changed symlinks
        # For every changed template in an <os> directory, collect all <os>/<version> directories that contain a symlink to the template.
        # For instance, if ubuntu/src-ubunut.pkr.hcl changes, find all subdirectories of 'ubuntu' that contain links to that file
        # -> the result would be e.g. 'ubuntu/focal ubuntu/jammy ubuntu/focal_desktop'
        id: get-symlink-dirs
        working-directory: "${{ github.repository }}"
        run: |
          # Loop over each changed <os>/*.hcl file
          for file in ${{ steps.changed-symlink-yaml.outputs.symlinks_all_changed_files }}; do
              dir=$(dirname $file)
              links=$(find "$dir" -type l) # Find all symlinks under the current $file's directory
              for link in $links; do
                # If this link has $file as a target, add the link's directory to the array of changed template directories
                if [[ $(readlink -f "$link") == $(realpath "$file") ]]; then
                  CHANGED="$CHANGED $(dirname $link)"
                fi
              done
          done
          # Store the results
          echo changed_dirs="$CHANGED" >> "$GITHUB_OUTPUT"
      - id: set-images-matrix
        run: |
          # First add together the directories found in the changed-images-yaml and changed-templates-yaml steps into a single array
          ALL_DIRS="${{ steps.changed-images-yaml.outputs.images_all_changed_files }} ${{ steps.get-changed-templates.outputs.changed_dirs }}"
          # Now construct a unique array out of ALL_DIRS
          MATRIX=($(echo "$ALL_DIRS" | xargs -n 1 | sort -u))
          # Next create a valid json array out of the bash array using jq
          MATRIX=$(printf '%s\n' "${MATRIX[@]}" | jq -R . | jq -c -s .)
          # Store the results
          echo images=$MATRIX >> $GITHUB_OUTPUT
          echo matrix={\"images\": $MATRIX} >> $GITHUB_OUTPUT
    outputs:
      images: ${{ steps.set-images-matrix.outputs.images }}
      images_matrix: ${{ steps.set-images-matrix.outputs.matrix }}

  build_and_deploy:
    needs: define_images
    runs-on: ubuntu-latest
    if: ${{ needs.define_images.outputs.images != '[""]' && needs.define_images.outputs.images_matrix != '' }}
    strategy:
      fail-fast: false
      matrix: ${{ fromJSON(needs.define_images.outputs.images_matrix) }}
    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          submodules: recursive
      - name: Login to GitHub Container Registry
        uses: docker/login-action@v3
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}
      - name: Build image
        id: build-image
        run: IMG=${{ matrix.images }} ./pack.sh docker
      - name: Get image name and tag # grep in the image directory's variables file to find the image name/tag to push to
        id: get-image-name
        run: |
          echo "docker_repo=`grep docker_repo ${{ matrix.images }}/variables.auto.pkrvars.hcl | awk '{print $3}'`"  >> "$GITHUB_OUTPUT"
      - name: Push image
        run: docker push ${{ steps.get-image-name.outputs.docker_repo }}