feat: implement PostHog proxy worker with CORS support and routing

Author: 8bitAlex

site/docusaurus.config.ts

@@ -55,7 +55,8 @@ const config: Config = {
           'posthog-docusaurus',
           {
             apiKey: process.env.POSTHOG_API_KEY,
-            appUrl: process.env.POSTHOG_HOST,
+            appUrl: 'https://raidcli.dev/ingest',
+            ui_host: process.env.POSTHOG_HOST,
             enableInDevelopment: false,
           },
         ]]

workers/posthog-proxy/src/index.ts

@@ -0,0 +1,33 @@
+const POSTHOG_ASSETS_HOST = 'https://us-assets.i.posthog.com';
+const POSTHOG_API_HOST = 'https://us.i.posthog.com';
+
+export default {
+  async fetch(request: Request): Promise<Response> {
+    const url = new URL(request.url);
+
+    // Strip the /ingest prefix
+    const path = url.pathname.replace(/^\/ingest/, '') || '/';
+
+    // Route static assets (JS bundle) to the CDN host, everything else to the API host
+    const origin = path.startsWith('/static/') ? POSTHOG_ASSETS_HOST : POSTHOG_API_HOST;
+    const target = new URL(path + url.search, origin);
+
+    const proxied = new Request(target.toString(), {
+      method: request.method,
+      headers: request.headers,
+      body: request.method !== 'GET' && request.method !== 'HEAD' ? request.body : null,
+    });
+
+    const response = await fetch(proxied);
+
+    // Pass through with CORS headers so the browser accepts the response
+    const headers = new Headers(response.headers);
+    headers.set('Access-Control-Allow-Origin', request.headers.get('Origin') ?? '*');
+    headers.set('Access-Control-Allow-Credentials', 'true');
+
+    return new Response(response.body, {
+      status: response.status,
+      headers,
+    });
+  },
+};

workers/posthog-proxy/wrangler.toml

@@ -0,0 +1,7 @@
+name = "posthog-proxy"
+main = "src/index.ts"
+compatibility_date = "2024-01-01"
+
+routes = [
+  { pattern = "raidcli.dev/ingest/*", zone_name = "raidcli.dev" },
+]