Add preview PR deployments

Signed-off-by: Nelo-T. Wallus <red.brush9525@fastmail.com>
Signed-off-by: Nelo-T. Wallus <n.wallus@sap.com>

Author: ntnn

.github/workflows/pages.yaml

@@ -7,19 +7,38 @@ on:
   pull_request:
     branches:
       - main
+    types:
+      - opened
+      - reopened
+      - synchronize
+      - closed
   workflow_dispatch:
 
 permissions:
   contents: write # to write the built page to the branch
 
+env:
+  PAGES_BASE: ${{ github.event_name == 'pull_request' && format('pr-preview/pr-{0}', github.event.pull_request.number) || '/' }}
+
 concurrency:
-  group: pages
+  # set separate concurrency groups for main and PR branches
+  group: ${{ github.event_name == 'pull_request' && format('pages-preview-{0}', github.event.pull_request.number) || 'pages-main' }}
   cancel-in-progress: false
 
 jobs:
 
+  delete-preview:
+    if: github.event_name == 'pull_request' && github.event.action == 'closed'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: rossjrw/pr-preview-action@v1
+        with:
+          action: remove
+
   build:
     runs-on: ubuntu-latest
+    # only build on main or if the PR is open
+    if: github.ref == 'refs/heads/main' || (github.event_name == 'pull_request' && github.event.action != 'closed')
     steps:
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
         with:
@@ -29,16 +48,24 @@ jobs:
           node-version: 22
           cache: npm
 
-      - uses: actions/configure-pages@983d7736d9b0ae728b81ab479565c72886d7745b # v5
+      - id: configure
+        uses: actions/configure-pages@983d7736d9b0ae728b81ab479565c72886d7745b # v5
 
       - run: npm ci
       - run: npm run build
 
+      # deploy the PR to a preview URL
       - uses: rossjrw/pr-preview-action@9f77b1d057b494e662c50b8ca40ecc63f21e0887 # v1
         if: ${{ github.event_name == 'pull_request' }}
         with:
           source-dir: .vitepress/dist
+      - uses: thollander/actions-comment-pull-request@v3
+        if: github.event_name == 'pull_request'
+        with:
+          message: |
+            A preview has been deployed to ${{ format('{0}/{1}', steps.configure.outputs.base_url, env.PAGES_BASE) }}
 
+      # deploy the build to GitHub Pages
       - uses: JamesIves/github-pages-deploy-action@6c2d9db40f9296374acc17b90404b6e8864128c8 # v4
         if: ${{ (github.event_name == 'push' || github.event_name == 'workflow_dispatch') && github.ref == 'refs/heads/main' }}
         with:

.vitepress/config.mts

@@ -5,6 +5,7 @@ import { fileURLToPath, URL } from 'node:url'
 export default withMermaid({
   title: "Platform Mesh",
 
+  base: process.env.PAGES_BASE ? process.env.PAGES_BASE : '/',
 
   description: "Platform Mesh - Building upon the Kubernetes API & Resource Model",
 
@@ -41,7 +42,6 @@ export default withMermaid({
       width: 24,
       height: 24
     },
-  
 
     outline: [2, 3, 4, 5],
 
@@ -63,7 +63,7 @@ export default withMermaid({
             ]
         }
       ],
-      
+
         '/scenarios': {
             test: 'Scenarios',
             items:  [
@@ -72,13 +72,11 @@ export default withMermaid({
             ],
         },
 
-
     },
-  
 
     socialLinks: [
       { icon: 'github', link: 'https://github.com/platform-mesh' }
     ]
   },
- 
+
 })