dependabot-differ.yaml

# Do NOT use any secrets in this workflow. This will result in serious security holes.
name: Dependabot Diff Checker

on:
  pull_request_target:
    types:
      - labeled

jobs:
  dependabot_diff:
    name: Site Build Difference
    runs-on: ubuntu-latest
    if: contains(github.event.pull_request.labels.*.name, 'dependencies') # See https://git.io/JsVv1
    steps:
      - name: Checkout Pull Request Branch
        uses: actions/checkout@v4
        with:
          ref: ${{ github.event.pull_request.head.sha }}
          submodules: true

      - name: Setup Ruby
        uses: ruby/setup-ruby@v1
        with:
          ruby-version: 3.1
          bundler-cache: true

      - name: Build Pull Request Version of Website
        run: |
          bundle install
          bundle exec jekyll build
          mv _site _site-pr

      - name: Checkout Default Branch
        uses: actions/checkout@v4
        with:
          clean: false
          submodules: true

      - name: Build Production Version of Website
        run: |
          bundle install
          bundle exec jekyll build

      - name: Compare Built Websites
        id: site-diff
        run: |
          has_changes=0
          site_diff=$(diff -r _site-pr _site) || has_changes=$?

          if [[ $has_changes == 0 ]]; then
            PR_COMMENT="
            There were no changes to the code of the compiled website as a result of this Dependabot update.
            "
          else
            PR_COMMENT="
            There were changes to the compiled website as a result of this Dependabot update:

            \`\`\`
            $site_diff
            \`\`\`
            "
          fi

          # Replace newlines and other special characters with escaped equivalents
          PR_COMMENT="${PR_COMMENT//'%'/'%25'}"
          PR_COMMENT="${PR_COMMENT//$'\n'/'%0A'}"
          PR_COMMENT="${PR_COMMENT//$'\r'/'%0D'}"

          echo "::set-output name=pr-comment::$PR_COMMENT"

      - name: Comment on the Pull Request
        uses: peter-evans/create-or-update-comment@v4
        with:
          issue-number: ${{ github.event.pull_request.number }}
          body: ${{ steps.site-diff.outputs.pr-comment }}