Ghost BunnyCDN Cache Purging Middleware

A simple BunnyCDN Edge Script (Middleware) to automatically purge the BunnyCDN cache for your Ghost blog based on Ghost's native X-Cache-Invalidate header.

This script provides a lightweight alternative to running a separate proxy service (like the original ghost-cache-invalidation-proxy by Magic Pages, which inspired this approach) if your primary goal is simply to purge the BunnyCDN cache.

How it Works

1. Intercepts Origin Response: The script uses BunnyCDN's onOriginResponse trigger, which executes after your Ghost origin server responds but before BunnyCDN caches the response.
2. Detects Header: It checks the response headers from Ghost for the X-Cache-Invalidate header.
3. Parses Paths: If the header is found, it parses the value (which can be /* for site-wide invalidation or specific paths like /post-slug/).
4. Calls Purge API: It uses the fetch API to make direct calls to the BunnyCDN Purge API (https://api.bunny.net/purge?url=...) for each path identified, using your API key for authentication.

Ghost sends the X-Cache-Invalidate header reliably for various actions, including:

• Publishing/unpublishing posts or pages (/*).
• Editing content of published posts/pages (specific paths like /post-slug/).
• Changing themes or site settings (/*).
• Updating tags, labels, users (/*).
• Comment actions (specific path of the post).

Why Use This?

• Simplicity: No separate proxy server/container to deploy, manage, or update.
• Leverages CDN: Runs directly on BunnyCDN's infrastructure.
• Direct Integration: Calls the BunnyCDN API directly.
• Resource Efficient: Avoids the need for resources to run a proxy.

Usage

1. Copy the Script: Get the code from the middleware.js file in this repository.
2. Navigate to Pull Zone: Log in to your BunnyCDN dashboard and go to the settings for the Pull Zone serving your Ghost site.
3. Add Edge Rule: Go to the "Edge Rules" tab. Click "Add Edge Rule".
4. Set Action: Choose the action "Execute EdgeScript".
5. Paste Code: Give the script a name (e.g., "Ghost Cache Invalidation") and paste the full JavaScript code from middleware.js into the editor.
6. Configure Environment Variables:
   • Scroll down to the "Environment Variables" section within the Edge Rule settings.
   • Click "Add Variable".
   • Add BUNNY_API_KEY and paste your actual BunnyCDN account API key as the value. (Required)
   • Optionally, click "Add Variable" again. Add GHOST_PUBLIC_URL and set its value to your blog's full public base URL (e.g., https://yourdomain.com). This is recommended to ensure correct purging of relative paths.
7. Set Trigger:
   • Add a trigger. A simple "Request URL" trigger matching * (all requests) is usually sufficient.
   • Important: Ensure the "Execute Before Cache Lookup" option is disabled. The script needs to run after the origin responds.
8. Save: Save the Edge Rule. Make sure it's enabled.

Now, cache purging based on Ghost updates should happen automatically via BunnyCDN.

License

MIT