Try with a custom entrypoint

Author: SamyPesse

bun.lockb

@@ -8,7 +8,8 @@
     },
     "packageManager": "[email protected]",
     "patchedDependencies": {
-        "@vercel/[email protected]": "patches/@vercel%[email protected]"
+        "@vercel/[email protected]": "patches/@vercel%[email protected]",
+        "@cloudflare/[email protected]": "patches/@cloudflare%[email protected]"
     },
     "private": true,
     "scripts": {

package.json

@@ -5,7 +5,7 @@
     "scripts": {
         "dev": "env-cmd --silent -f ../../.env.local next dev",
         "build": "next build",
-        "build:cloudflare": "next-on-pages",
+        "build:cloudflare": "next-on-pages --custom-entrypoint=./src/cloudflare-entrypoint.ts",
         "start": "next start",
         "lint": "next lint",
         "typecheck": "tsc --noEmit",

packages/gitbook/package.json

@@ -0,0 +1,20 @@
+// @ts-ignore
+import nextOnPagesHandler from '@cloudflare/next-on-pages/fetch-handler';
+
+import { withMiddlewareHeadersStorage } from './lib/middleware';
+
+/**
+ * We use a custom entrypoint until we can move to opennext (https://github.com/opennextjs/opennextjs-cloudflare/issues/92).
+ * There is a bug in next-on-pages where headers can't be set on the response in the middleware for RSC requests (https://github.com/cloudflare/next-on-pages/issues/897).
+ */
+export default {
+    async fetch(request, env, ctx) {
+        console.log('start custom fetch');
+        const response = await withMiddlewareHeadersStorage(() =>
+            nextOnPagesHandler.fetch(request, env, ctx),
+        );
+        console.log('end custom fetch');
+
+        return response;
+    },
+} as ExportedHandler<{ ASSETS: Fetcher }>;

packages/gitbook/src/cloudflare-entrypoint.ts

@@ -1,3 +1,37 @@
+import { AsyncLocalStorage } from 'node:async_hooks';
+
+const responseHeadersLocalStorage = new AsyncLocalStorage<Headers>();
+
+/**
+ * Set a header on the middleware response.
+ * We do this because of https://github.com/opennextjs/opennextjs-cloudflare/issues/92
+ * It can be removed as soon as we move to opennext where hopefully this is fixed.
+ */
+export function setMiddlewareHeader(response: Response, name: string, value: string) {
+    const responseHeaders = responseHeadersLocalStorage.getStore();
+    response.headers.set(name, value);
+
+    if (responseHeaders) {
+        responseHeaders.set(name, value);
+    }
+}
+
+/**
+ * Wrap some middleware with a the storage to store headers.
+ */
+export async function withMiddlewareHeadersStorage(
+    handler: () => Promise<Response>,
+): Promise<Response> {
+    const responseHeaders = new Headers();
+    const response = await responseHeadersLocalStorage.run(responseHeaders, handler);
+
+    for (const [name, value] of responseHeaders.entries()) {
+        response.headers.set(name, value);
+    }
+
+    return response;
+}
+
 /**
  * For a given GitBook URL, return a list of alternative URLs that could be matched against to lookup the content.
  * The approach is optimized to aim at reusing cached lookup results as much as possible.

packages/gitbook/src/lib/middleware.ts

@@ -20,7 +20,7 @@ import {
 import { race } from '@/lib/async';
 import { buildVersion } from '@/lib/build';
 import { createContentSecurityPolicyNonce, getContentSecurityPolicy } from '@/lib/csp';
-import { getURLLookupAlternatives, normalizeURL } from '@/lib/middleware';
+import { getURLLookupAlternatives, normalizeURL, setMiddlewareHeader } from '@/lib/middleware';
 import {
     VisitorAuthCookieValue,
     getVisitorAuthCookieName,
@@ -253,14 +253,14 @@ export async function middleware(request: NextRequest) {
         resolved.cookies,
     );
 
-    response.headers.set('x-gitbook-version', buildVersion());
+    setMiddlewareHeader(response, 'x-gitbook-version', buildVersion());
 
     // Add Content Security Policy header
-    response.headers.set('content-security-policy', csp);
+    setMiddlewareHeader(response, 'content-security-policy', csp);
     // Basic security headers
-    response.headers.set('strict-transport-security', 'max-age=31536000');
-    response.headers.set('referrer-policy', 'no-referrer-when-downgrade');
-    response.headers.set('x-content-type-options', 'nosniff');
+    setMiddlewareHeader(response, 'strict-transport-security', 'max-age=31536000');
+    setMiddlewareHeader(response, 'referrer-policy', 'no-referrer-when-downgrade');
+    setMiddlewareHeader(response, 'x-content-type-options', 'nosniff');
 
     const isPrefetch = request.headers.has('x-middleware-prefetch');
 
@@ -273,28 +273,24 @@ export async function middleware(request: NextRequest) {
     //         'private, no-cache, no-store, max-age=0, must-revalidate',
     //     );
     // } else {
-        if (typeof resolved.cacheMaxAge === 'number') {
-            const cacheControl = `public, max-age=0, s-maxage=${resolved.cacheMaxAge}, stale-if-error=0`;
-
-            if (
-                process.env.GITBOOK_OUTPUT_CACHE === 'true' &&
-                process.env.NODE_ENV !== 'development'
-            ) {
-                response.headers.set('cache-control', cacheControl);
-                response.headers.set('Cloudflare-CDN-Cache-Control', cacheControl);
-            } else {
-                response.headers.set('x-gitbook-cache-control', cacheControl);
-            }
+    if (typeof resolved.cacheMaxAge === 'number') {
+        const cacheControl = `public, max-age=0, s-maxage=${resolved.cacheMaxAge}, stale-if-error=0`;
+
+        if (process.env.GITBOOK_OUTPUT_CACHE === 'true' && process.env.NODE_ENV !== 'development') {
+            setMiddlewareHeader(response, 'cache-control', cacheControl);
+            setMiddlewareHeader(response, 'Cloudflare-CDN-Cache-Control', cacheControl);
+        } else {
+            setMiddlewareHeader(response, 'x-gitbook-cache-control', cacheControl);
         }
+    }
     // }
 
     if (resolved.cacheTags && resolved.cacheTags.length > 0) {
         const headerCacheTag = resolved.cacheTags.join(',');
-        response.headers.set('cache-tag', headerCacheTag);
-        response.headers.set('x-gitbook-cache-tag', headerCacheTag);
+        setMiddlewareHeader(response, 'cache-tag', headerCacheTag);
+        setMiddlewareHeader(response, 'x-gitbook-cache-tag', headerCacheTag);
     }
 
-    console.log('headers end', Array.from(response.headers.entries()));
     return response;
 }
 

packages/gitbook/src/middleware.ts

@@ -0,0 +1,12 @@
+diff --git a/dist/index.js b/dist/index.js
+index 32fec63484ec332eb291a7253e5e168223627535..653dee64794140bafe57219356c712b197c17530 100644
+--- a/dist/index.js
++++ b/dist/index.js
+@@ -6983,6 +6983,7 @@ async function buildWorkerFile({ vercelConfig, vercelOutput }, {
+       outfile: outputFile,
+       allowOverwrite: true,
+       bundle: true,
++      external: ["node:*", "cloudflare:*"],
+       plugins: [
+         {
+           name: "custom-entrypoint-import-plugin",