Generate link with how changes to the site look on PR

[edwardchalstrey1]

Requested enahancement or feature

On PR to main, a build of the site should be made (and accessible on a link) from the new branch that can be checked before merge

Note: this may not be possible due to GitHub pages being set up with an external URL

[edwardchalstrey1]

Netlify option

Co-pilot suggests that the problem with PR previews can be got around by using Netlify: https://www.netlify.com/

TODO:

• Check if Turing has a Netlify subscription - note: the repo is not a Turing one
• Will likely need someone with full admin access to this repo to try adding the secrets required (see below)
  • I think we should be ok with the free tier but unsure
• Open a PR adding a GH action config similar to below

Proposed config .github/workflows/pr-preview.yml:

name: PR Preview Build

on:
  pull_request:
    branches: [ main ]
    types: [opened, synchronize, reopened, closed]

jobs:
  build-preview:
    runs-on: ubuntu-latest
    if: github.event.action != 'closed'
    
    steps:
    - name: Checkout repository
      uses: actions/checkout@v4
      with:
        submodules: recursive
        fetch-depth: 0
    
    - name: Setup Hugo
      uses: peaceiris/actions-hugo@v2
      with:
        hugo-version: '0.119.0'
        extended: true
    
    - name: Setup Node.js
      uses: actions/setup-node@v4
      with:
        node-version: '18'
    
    - name: Install Dart Sass
      run: npm install -g sass-embedded
    
    - name: Build Hugo site for PR preview
      run: |
        # Set base URL for PR preview (will be updated by Netlify)
        hugo --minify --baseURL "/"
    
    - name: Deploy to Netlify
      uses: nwtgck/actions-netlify@v3.0
      with:
        publish-dir: './public'
        production-branch: main
        github-token: ${{ secrets.GITHUB_TOKEN }}
        deploy-message: "Deploy from GitHub Actions - PR #${{ github.event.number }}"
        enable-pull-request-comment: true
        enable-commit-comment: false
        overwrites-pull-request-comment: true
      env:
        NETLIFY_AUTH_TOKEN: ${{ secrets.NETLIFY_AUTH_TOKEN }}
        NETLIFY_SITE_ID: ${{ secrets.NETLIFY_SITE_ID }}
      timeout-minutes: 5

  cleanup-preview:
    runs-on: ubuntu-latest
    if: github.event.action == 'closed'
    
    steps:
    - name: Clean up Netlify deployment
      uses: nwtgck/actions-netlify@v3.0
      with:
        publish-dir: './public'
        production-branch: main
        github-token: ${{ secrets.GITHUB_TOKEN }}
        deploy-message: "Cleanup PR #${{ github.event.number }}"
        enable-pull-request-comment: false
      env:
        NETLIFY_AUTH_TOKEN: ${{ secrets.NETLIFY_AUTH_TOKEN }}
        NETLIFY_SITE_ID: ${{ secrets.NETLIFY_SITE_ID }}
      timeout-minutes: 2