Ghost BunnyCDN Cache Purger

Motivation

BunnyCDN's Perma-Cache feature retains files in a new directory structure after a full pull zone purge. While this can improve performance in some scenarios, it may lead to unnecessary storage costs over time. This webhook-based solution automates the clearing of old cache folders, preventing excessive space usage and associated expenses.

Features

• Automatically purges BunnyCDN pull zone cache upon receiving a webhook from Ghost CMS
• Clears old Perma-Cache folders to prevent unnecessary storage usage
• Verifies webhook signatures for security
• Logs detailed information for easy debugging and monitoring
• Designed to run as a Cloudflare Worker for scalability and low latency

Installation

1. Clone this repository:

   git clone https://github.com/yourusername/bunnycdn-cache-purger.git
   

2. Set up a Cloudflare Worker:

   • Log in to your Cloudflare account and navigate to the Workers section
   • Create a new Worker and paste the contents of index.js into the script editor

3. Set up environment variables in your Cloudflare Worker:

   • GHOST_WEBHOOK_SECRET: Your Ghost webhook secret
   • BUNNY_PULLZONE_ID: Your BunnyCDN pull zone ID
   • BUNNY_API_KEY: Your BunnyCDN account API key
   • BUNNY_STORAGE_ZONE_HOSTNAME: Your storage zone hostname (e.g., "ny.storage.bunnycdn.com")
   • BUNNY_STORAGE_ZONE_NAME: Your storage zone name
   • BUNNY_STORAGE_ZONE_PASSWORD: Your storage zone password

4. Configure your Ghost CMS to send webhooks to your Cloudflare Worker URL when content is published or updated

Code Overview

Main Request Handler

The handleRequest function is the main entry point for processing requests:

1. It first checks if all required environment variables are set.
2. It then examines the request path.
3. If the path is '/purge-full-cache', it proceeds with the cache purging process.

Authentication

The code supports two types of authentication:

1. Manual Trigger: It checks for a 'manualtriggertoken' header. If this matches the MANUAL_TRIGGER_TOKEN environment variable, it bypasses further authentication.

2. Ghost Webhook Verification: If it's not a manual trigger, it verifies the request signature using the verifySignature function. This function:

   • Extracts the signature and timestamp from the 'X-Ghost-Signature' header.
   • Checks if the timestamp is within 5 minutes of the current time.
   • Computes a hash using the request body, timestamp, and the GHOST_WEBHOOK_SECRET.
   • Compares the computed hash with the provided signature.

Cache Purging

If authentication is successful, the code proceeds to purge the BunnyCDN cache:

1. It sends a POST request to the BunnyCDN API to purge the entire pull zone cache.
2. The pull zone ID and API key are taken from environment variables.

Perma-Cache Cleanup

After successfully purging the cache, it calls the cleanupPermaCacheFolders function:

1. This function first fetches a list of all folders in the 'bcdn_perma_cache' directory of the BunnyCDN storage zone.
2. It then iterates through each folder and sends a DELETE request to remove it.
3. It keeps track of successful deletions and failures.

Error Handling and Logging

Throughout the code, there are numerous console.log statements for debugging and error tracking. Each major function also has try-catch blocks to handle and log errors.

Response

The worker responds with different HTTP status codes based on the outcome:

• 200: Successful cache purge and cleanup
• 403: Invalid signature
• 404: Invalid path
• 500: Any other errors

License

This project is licensed under the MIT License.