Add logging for request duration and response details in 2c (#3583)

Co-authored-by: Nicolas Dorseuil <nicolas@gitbook.io>

packages/gitbook/openNext/customWorkers/middleware.js

@@ -7,12 +7,37 @@ export { DOQueueHandler } from '../../.open-next/.build/durable-objects/queue.js
 
 export { DOShardedTagCache } from '../../.open-next/.build/durable-objects/sharded-tag-cache.js';
 
+//Format used by the tail logger
+const formatLog = (requestDuration, responseCode, responseCache, responseRoute) =>
+    `%${JSON.stringify({ requestDuration, responseCode, responseCache, responseRoute })}%[main] Response Done`;
+
+const getResolvedRoute = (reqOrResp, defaultValue) => {
+    try {
+        const resolvedRoutes = JSON.parse(
+            reqOrResp.headers.get('x-opennext-resolved-routes') ?? ''
+        )[0].route;
+        return resolvedRoutes ?? defaultValue;
+    } catch {
+        return defaultValue;
+    }
+};
+
 export default class extends WorkerEntrypoint {
     async fetch(request) {
         return runWithCloudflareRequestContext(request, this.env, this.ctx, async () => {
+            const startTime = Date.now();
             // - `Request`s are handled by the Next server
             const reqOrResp = await middlewareHandler(request, this.env, this.ctx);
             if (reqOrResp instanceof Response) {
+                const duration = Date.now() - startTime;
+                const logMessage = formatLog(
+                    duration,
+                    reqOrResp.status,
+                    reqOrResp.headers.get('x-opennext-cache') ?? 'MISS',
+                    getResolvedRoute(reqOrResp, 'middleware')
+                );
+                // biome-ignore lint/suspicious/noConsole: <explanation>
+                console.log(logMessage);
                 return reqOrResp;
             }
 
@@ -22,12 +47,22 @@ export default class extends WorkerEntrypoint {
                     'Cloudflare-Workers-Version-Overrides',
                     `gitbook-open-v2-${this.env.STAGE}="${this.env.WORKER_VERSION_ID}"`
                 );
-                return this.env.DEFAULT_WORKER?.fetch(reqOrResp, {
+                const response = await this.env.DEFAULT_WORKER?.fetch(reqOrResp, {
                     redirect: 'manual',
                     cf: {
                         cacheEverything: false,
                     },
                 });
+                const formatedLog = formatLog(
+                    Date.now() - startTime,
+                    response.status,
+                    `SERVER-${response.headers.get('x-nextjs-cache') ?? 'MISS'}`,
+                    getResolvedRoute(reqOrResp, 'unresolved')
+                );
+                // biome-ignore lint/suspicious/noConsole: <explanation>
+                console.log(formatedLog);
+
+                return response;
             }
             // If we are in preview mode, we need to send the request to the preview URL
             const modifiedUrl = new URL(reqOrResp.url);