feat: Broaden middleware's internal URL correction to include hosts like klz-app and localhost, and update Varnish's health check URL to /health.

middleware.ts

@@ -19,25 +19,31 @@ export default function middleware(request: NextRequest) {
     headerObj[key] = value;
   });
 
-  // Defensive URL correction
-  // If the URL contains 0.0.0.0 (internal IP), we rebuild it using the Host header
+  // Defensive URL correction for internal container leakage (0.0.0.0, klz-app, localhost)
+  // This prevents hydration mismatches and host poisoning in generated links/metadata.
+  const urlObj = new URL(url);
+  const internalHosts = ['0.0.0.0', 'klz-app', 'localhost', '127.0.0.1'];
+
   let effectiveRequest = request;
-  if (url.includes('0.0.0.0')) {
+  if (internalHosts.includes(urlObj.hostname)) {
     const proto = headers.get('x-forwarded-proto') || 'https';
-    const host = headers.get('x-forwarded-host') || headers.get('host') || 'testing.klz-cables.com';
-    const newUrl = new URL(url);
-    newUrl.protocol = proto;
-    // Split host to remove port if present
-    const [hostname] = host.split(':');
-    newUrl.hostname = hostname;
-    newUrl.port = ''; // Explicitly clear the port to avoid leaking :3000
-    effectiveRequest = new NextRequest(newUrl, {
+    // Prioritize x-forwarded-host (passed by Traefik) over the local Host header
+    const hostHeader =
+      headers.get('x-forwarded-host') || headers.get('host') || 'testing.klz-cables.com';
+    const [publicHostname] = hostHeader.split(':');
+
+    urlObj.protocol = proto;
+    urlObj.hostname = publicHostname;
+    urlObj.port = ''; // Explicitly clear internal port (3000)
+
+    effectiveRequest = new NextRequest(urlObj, {
       headers: request.headers,
       method: request.method,
       body: request.body,
     });
+
     console.log(
-      `Replaced 0.0.0.0 URL with: ${newUrl.toString()} | Original Host: ${headers.get('host')} | Forwarded Host: ${headers.get('x-forwarded-host')}`,
+      `🛡️ Middleware: Fixed internal URL leak: ${url} -> ${urlObj.toString()} | Proto: ${proto} | Host: ${hostHeader}`,
     );
   }
 

varnish/default.vcl

@@ -3,7 +3,7 @@ vcl 4.1;
 import std;
 
 probe default_probe {
-    .url = "/en";
+    .url = "/health";
     .timeout = 2s;
     .interval = 5s;
     .window = 5;