Merge pull request open-life-science#1007 from open-life-science/pr_preview

Improve pr-preview action to accomodate previews for multiple open PRs

Author: Tajuddeen1

.github/workflows/deploy-preview.yml

@@ -4,48 +4,58 @@ on:
   pull_request:   # Run this workflow whenever a Pull Request (PR) is made...
     branches:
       - main   # ...only if the PR targets the 'main' branch
+  workflow_dispatch:   # Allow manual trigger of workflow from "Actions" tab
 
 jobs:
   build-and-deploy:
     runs-on: ubuntu-latest   # Use the latest Ubuntu virtual machine
 
     steps:
     - name: Checkout code
-      uses: actions/checkout@v3   # Step 1: Get (clone) the repository code
+      uses: actions/checkout@v3   # Step 1: Get (clone) the repository code.
 
-    - name: Set up Ruby   # Step 2: Set up Ruby for the runner
+    - name: Set up Ruby   # Step 2: Set up Ruby for the runner.
       uses: ruby/setup-ruby@v1
       with:
         ruby-version: 3.1   # Use Ruby version 3.1
         bundler-cache: true   # Cache Ruby gems for quicker builds
 
-    - name: Install dependencies   # Step 3: Install all Ruby packages required for the site
+    - name: Install dependencies   # Step 3: Install all Ruby packages required for the site.
       run: |
         bundle install   
 
-    - name: Build Jekyll site   # Step 4: Build the site with Jekyll, and put it in '_site' directory
+    - name: Build Jekyll site   # Step 4: Build the site with Jekyll, and put it in '_site' directory.
       run: |
         bundle exec jekyll build --destination _site
 
-    # Step 5: Make a folder called 'pr_preview'; move the built site into a subfolder labelled with the PR number
-    - name: Copy site to PR-specific folder    
+    # Step 5: Clone existing gh-pages branch. This preserves previously deployed PR previews.    
+    - name: Clone existing gh-pages branch
       run: |
-        mkdir pr_preview 
-        mv _site pr_preview/${{ github.event.pull_request.number }}
+        git config --global user.name 'github-actions'
+        git config --global user.email 'github-actions@github.com'
+        git clone --depth 1 --branch gh-pages https://x-access-token:${{ secrets.PR_PREVIEW_TOKEN }}@github.com/open-life-science/ols-site-preview.git gh-pages
+      env:
+        GIT_TERMINAL_PROMPT: 0
+    
+    # Step 6: Copy the built site into the PR folder, so every PR has its own preview.    
+    - name: Copy built site into PR folder   
+      run: |
+        pr_number=${{ github.event.pull_request.number }}
+        mkdir -p gh-pages/$pr_number
+        rm -rf gh-pages/$pr_number/*
+        cp -r _site/* gh-pages/$pr_number/
 
-    - name: Deploy to GitHub Pages for preview
-      uses: peaceiris/actions-gh-pages@v3   # Step 6: Use a pre-made action to deploy to GitHub Pages
-      with:
-        personal_token: ${{ secrets.PR_PREVIEW_TOKEN }} # GitHub token (from secrets) to authenticate this action and publish a preview.
-        publish_branch: gh-pages   # Publish to 'gh-pages' branch
-        publish_dir: ./pr_preview   # Use 'pr_preview' folder as the root for published files
-        external_repository: open-life-science/ols-site-preview   # Publish to external repo
-        cname: ''
+    - name: Push updated preview site
+      run: |
+        cd gh-pages
+        git add .
+        git commit -m "Deploy preview for PR #${{ github.event.pull_request.number }}"
+        git push origin gh-pages
 
     - name: Comment with preview URL
       env:
-        GITHUB_TOKEN: ${{ secrets.PR_PREVIEW_TOKEN }}   # Step 7a: Use token for authentication
-      run: | # Step 7b: Create a preview URL using the PR number, post a comment with the preview link on this PR
-        PREVIEW_URL="https://we-are-ols.org/ols-site-preview/${{ github.event.pull_request.number }}"
+        GITHUB_TOKEN: ${{ secrets.PR_PREVIEW_TOKEN }}   # Step 7a: Use token for authentication.
+      run: | # Step 7b: Create a preview URL using the PR number, post a comment with the preview link on this PR.
+        PREVIEW_URL="https://we-are-ols.org/ols-site-preview/${{ github.event.pull_request.number }}/"
         COMMENT_BODY="🎉 A preview of this PR is available at: [${PREVIEW_URL}](${PREVIEW_URL})"
         gh pr comment ${{ github.event.pull_request.number }} --body "$COMMENT_BODY"