Action: Add workflow for automated preview deployments on latest

Author: lamATnginx

.github/workflows/previews.yml

@@ -0,0 +1,29 @@
+name: documentation preview
+
+on: 
+  release: 
+    types: 
+      - published
+  pull_request:
+    branches:
+      - "*"
+
+jobs:
+    build:
+      runs-on: ubuntu-latest
+      steps:
+        - name: Trigger `Build and deploy` workflow in `documentation` repo
+          run: |
+            repo_owner="nginx" 
+            repo_name="documentation"  
+            event_type="trigger-preview-build" 
+            environment="preview"
+            theme_version="${{ github.head_ref || '' }}" # Will either be the branch name if triggered from pull request, or empty string (aka latest) if triggered from release
+
+            curl -L \
+            -X POST \
+            -H "Accept: application/vnd.github+json" \
+            -H "Authorization: Bearer ${{ secrets.PERSONAL_ACCESS_TOKEN }}" \
+            -H "X-GitHub-Api-Version: 2022-11-28" \
+            https://api.github.com/repos/$repo_owner/$repo_name/dispatches \
+            -d "{\"event_type\": \"$event_type\", \"client_payload\": {\"environment\": \"$environment\", \"hugo_theme_override\": \"$theme_version\"}}"

.github/workflows/theme-release.yml

@@ -1,16 +1,18 @@
 name: Slack notification for new theme release
 
 on: 
-  release: 
-    types: 
-      - published
+  workflow_run:
+    workflows:
+      - "documentation preview"
+    types: [completed]
 
 permissions:
   contents: read
 
 jobs:
     release-notification:
         runs-on: ubuntu-latest
+        if: ${{ github.event.workflow_run.event == 'release' }}
         permissions:
           contents: read
           actions: read # for 8398a7/action-slack