Merge pull request #6 from magicpages/add-public-url-variable

Update environment configuration and versioning

Author: betschki

README.md

@@ -18,6 +18,17 @@ The `magicpages/ghost-cache-invalidation-proxy` Docker image is available on [Do
 
 ### Environment Variables
 
+#### URL Configuration
+
+The proxy supports two URL configurations to handle different deployment scenarios:
+
+- **`GHOST_URL`**: The internal URL used to communicate with your Ghost instance (e.g., `http://ghost:2368` in Docker networks)
+- **`GHOST_PUBLIC_URL`** (optional): The public-facing URL of your Ghost site (e.g., `https://yourdomain.com`)
+
+When `GHOST_PUBLIC_URL` is not provided, the proxy will send relative URLs (like `/post-slug`) to your webhook endpoint. When `GHOST_PUBLIC_URL` is configured, the proxy will convert these to absolute URLs (like `https://yourdomain.com/post-slug`).
+
+This is particularly useful for CDNs that require absolute URLs for cache purging, or when your internal Ghost URL differs from your public domain.
+
 #### Required variables
 
 - `GHOST_URL`: The URL of your Ghost CMS instance. Ideally, the hostname of your Ghost container and the port it listens on (e.g., `http://ghost:2368`).
@@ -57,6 +68,7 @@ services:
     image: magicpages/ghost-cache-invalidation-proxy:latest
     environment:
       - GHOST_URL=http://ghost:2368
+      - GHOST_PUBLIC_URL=https://yourdomain.com
       - PORT=4000
       - DEBUG=true
       - WEBHOOK_URL=https://api.example.com/invalidate

docker-compose.example.yml

@@ -14,16 +14,17 @@ services:
     build:
       context: .
     environment:
-      - GHOST_URL=http://ghost:2368
-      - PORT=4000
-      - DEBUG=true
-      - WEBHOOK_URL=https://api.example.com/invalidate
-      - WEBHOOK_METHOD=POST
-      - WEBHOOK_SECRET=your_secret_key
-      - WEBHOOK_HEADERS={"Custom-Header": "Value", "Authorization": "Bearer ${secret}"}
-      - WEBHOOK_BODY_TEMPLATE={"urls": ${urls}, "timestamp": "${timestamp}", "purgeAll": ${purgeAll}}
-      - WEBHOOK_RETRY_COUNT=3
-      - WEBHOOK_RETRY_DELAY=1000
+      GHOST_URL: http://ghost:2368
+      GHOST_PUBLIC_URL: https://your-blog.com # Optional: If set, webhook URLs will be absolute
+      WEBHOOK_URL: https://api.example.com/invalidate
+      PORT: 4000
+      DEBUG: "true"
+      WEBHOOK_METHOD: POST
+      WEBHOOK_SECRET: your_secret_key
+      WEBHOOK_HEADERS: '{"AccessKey": "$${secret}", "Content-Type": "application/json"}'
+      WEBHOOK_BODY_TEMPLATE: '{"urls": $${urls}}'
+      WEBHOOK_RETRY_COUNT: 3
+      WEBHOOK_RETRY_DELAY: 1000
     ports:
       - "4000:4000"
     depends_on:

example.env

@@ -4,6 +4,10 @@
 # The URL of your Ghost CMS instance (required)
 GHOST_URL=http://ghost:2368
 
+# Optional: The public-facing URL of your Ghost site (for absolute URL generation in cache purge requests)
+# Use this when your internal Ghost URL differs from the public domain
+# GHOST_PUBLIC_URL=https://yourdomain.com
+
 # The URL for the webhook endpoint that will be called when cache invalidation is needed (required)
 WEBHOOK_URL=https://api.example.com/invalidate
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "ghost-cache-invalidation-proxy",
-  "version": "1.0.1",
+  "version": "1.1.0",
   "description": "A proxy between a Ghost CMS instance and configurable webhooks for cache invalidation.",
   "main": "dist/index.js",
   "author": "Jannis Fedoruk-Betschki <[email protected]>",

src/config.ts

@@ -5,6 +5,7 @@ import type { MiddlewareConfig } from './types.js'
 // Schema for runtime environment validation
 const baseSchema = z.object({
   GHOST_URL: z.string().url().default('http://localhost:2368'),
+  GHOST_PUBLIC_URL: z.string().url().optional(),
   PORT: z.string().transform(Number).default('3000'),
   DEBUG: z.string().transform(val => val === 'true').default('false'),
   WEBHOOK_URL: z.string().url(),
@@ -57,6 +58,7 @@ export function loadConfig(): MiddlewareConfig {
 
   return {
     ghostUrl: data.GHOST_URL.replace(/\/$/, ''),
+    ghostPublicUrl: data.GHOST_PUBLIC_URL?.replace(/\/$/, ''),
     port: data.PORT,
     debug: data.DEBUG,
     webhook: {

src/index.ts

@@ -7,6 +7,9 @@ async function bootstrap() {
     const config = loadConfig();
     const app = express();
 
+    // Disable X-Powered-By header for security
+    app.disable('x-powered-by');
+    
     // Basic security
     app.set('trust proxy', config.security.trustProxy);
 
@@ -34,6 +37,9 @@ async function bootstrap() {
       console.log(`🚀 Server running on port ${config.port}`);
       config.debug && console.log('🐛 Debug mode enabled');
       console.log(`🔗 Connected to Ghost CMS at ${config.ghostUrl}`);
+      if (config.ghostPublicUrl) {
+        console.log(`🌐 Public site URL: ${config.ghostPublicUrl}`);
+      }
       console.log(`📣 Webhook configured at ${config.webhook.url}`);
     });
   } catch (error: unknown) {

src/middleware.ts

@@ -76,8 +76,17 @@ export class ProxyMiddleware {
       console.log('📋 Response headers:', proxyRes.headers);
     }
 
+    // Filter out potentially sensitive headers
+    const filteredHeaders = { ...proxyRes.headers };
+    
+    // Remove headers that might expose server information
+    delete filteredHeaders['x-powered-by'];
+    delete filteredHeaders['server'];
+    delete filteredHeaders['x-aspnet-version'];
+    delete filteredHeaders['x-aspnetmvc-version'];
+    
     // Forward the response headers and status code
-    res.writeHead(proxyRes.statusCode || 200, proxyRes.headers);
+    res.writeHead(proxyRes.statusCode || 200, filteredHeaders);
 
     // Pipe the response body
     proxyRes.pipe(res);

src/types.ts

@@ -1,5 +1,6 @@
 export interface MiddlewareConfig {
   ghostUrl: string;
+  ghostPublicUrl?: string;
   port: number;
   debug: boolean;
   webhook: {

src/webhook.ts

@@ -45,10 +45,21 @@ export class WebhookManager {
     // - "/post-permalink" - Single post
     // - "/, /page/*, /rss" - Multiple pages
     // - "/page/*" - Wildcard paths
-    const urls = purgeAll 
+    let urls = purgeAll 
       ? ['/*'] 
       : pattern.split(',').map(url => url.trim());
 
+    // If ghostPublicUrl is configured, convert relative URLs to absolute URLs
+    if (this.config.ghostPublicUrl && !purgeAll) {
+      urls = urls.map(url => {
+        // Only process relative URLs (starting with /)
+        if (url.startsWith('/')) {
+          return `${this.config.ghostPublicUrl}${url}`;
+        }
+        return url;
+      });
+    }
+    
     // From Ghost documentation, common patterns include:
     // - "/" - Home page
     // - "/page/*" - Paginated pages