pr-preview.yml

# Workflow for building and deploying a preview of the Hugo site for a pull request
name: Deploy Preview

on:
  # Runs on pull requests targeting the main branch
  pull_request_target:
    branches:
      - main

# Sets permissions of the GitHub TOKEN to allow deployment to GitHub Pages
permissions:
  contents: read
  pages: write
  id-token: write

# Allow one concurrent deployment per pull request, and cancel in-progress runs.
concurrency:
  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
  cancel-in-progress: true

# Default to bash
defaults:
  run:
    shell: bash

jobs:
  # Build job
  build:
    runs-on: ubuntu-latest
    outputs:
      preview_url: ${{ steps.base_url.outputs.base_url }}
    env:
      HUGO_VERSION: 0.148.2
    steps:
      - name: Install Hugo CLI
        run: |
          wget -O ${{ runner.temp }}/hugo.deb https://github.com/gohugoio/hugo/releases/download/v${HUGO_VERSION}/hugo_extended_${HUGO_VERSION}_linux-amd64.deb \
          && sudo dpkg -i ${{ runner.temp }}/hugo.deb
      - name: Install Dart Sass
        env:
          DART_SASS_VERSION: 1.83.4
        run: |
          wget -O /tmp/dart-sass.tar.gz \
            "https://github.com/sass/dart-sass/releases/download/${DART_SASS_VERSION}/dart-sass-${DART_SASS_VERSION}-linux-x64.tar.gz"
          tar -xf /tmp/dart-sass.tar.gz -C /tmp
          echo "/tmp/dart-sass" >> $GITHUB_PATH
      - name: Setup Pages
        id: pages
        uses: actions/configure-pages@v5

      # Build production site from base branch
      - name: Checkout base branch
        uses: actions/checkout@v4
        with:
          ref: ${{ github.base_ref }}
          path: base
          submodules: recursive
      - name: Install Node.js dependencies for base
        working-directory: base
        run: "[[ -f package-lock.json || -f npm-shrinkwrap.json ]] && npm ci || true"
      - name: Build production site
        env:
          HUGO_ENVIRONMENT: production
          HUGO_ENV: production
        run: |
          hugo \
            --source base \
            --minify \
            --baseURL "${{ steps.pages.outputs.base_url }}/" \
            --destination "${{ github.workspace }}/public"

      # Build PR preview
      - name: Checkout PR branch
        uses: actions/checkout@v4
        with:
          ref: ${{ github.event.pull_request.head.sha }}
          path: pr
          submodules: recursive
          fetch-depth: 0
      - name: Install Node.js dependencies for PR
        working-directory: pr
        run: "[[ -f package-lock.json || -f npm-shrinkwrap.json ]] && npm ci || true"
      - name: Set preview baseURL
        id: base_url
        run: echo "base_url=${{ steps.pages.outputs.base_url }}/pr-${{ github.event.number }}" >> $GITHUB_OUTPUT
      - name: Build PR preview
        env:
          HUGO_ENVIRONMENT: production
          HUGO_ENV: production
        run: |
          hugo \
            --source pr \
            --minify \
            --baseURL "${{ steps.base_url.outputs.base_url }}/" \
            --destination "${{ github.workspace }}/public/pr-${{ github.event.number }}"

      - name: Copy legacy SEN assets for PR preview
        working-directory: pr
        env:
          PUBLIC_DIR: ${{ github.workspace }}/public/pr-${{ github.event.number }}
        run: node scripts/copy-legacy-sen-assets.mjs

      - name: Check internal links
        working-directory: pr
        env:
          SITE_BASE_URL: ${{ steps.base_url.outputs.base_url }}/
          PUBLIC_DIR: ${{ github.workspace }}/public/pr-${{ github.event.number }}
          LINK_CHECK_BASE_REF: origin/${{ github.base_ref }}
        run: node scripts/check-changed-links.mjs

      - name: Upload artifact
        uses: actions/upload-pages-artifact@v3
        with:
          path: ./public

  # Deployment job
  deploy:
    environment:
      name: github-pages
      url: ${{ needs.build.outputs.preview_url }}
    runs-on: ubuntu-latest
    needs: build
    steps:
      - name: Deploy to GitHub Pages
        id: deployment
        uses: actions/deploy-pages@v4
  add-comment:
    runs-on: ubuntu-latest
    needs: [build, deploy]
    permissions:
      pull-requests: write
    steps:
      - name: Add preview URL to PR
        uses: peter-evans/create-or-update-comment@v4
        with:
          issue-number: ${{ github.event.pull_request.number }}
          body: | # This is a multiline string, so newlines are preserved correctly.
            Preview deployed at: ${{ needs.build.outputs.preview_url }}