feat(nextjs): Hint correct middleware location when missing clerkMidd…

…leware (#4979)

.changeset/fuzzy-rockets-smash.md

@@ -0,0 +1,5 @@
+---
+'@clerk/nextjs': patch
+---
+
+Improve error messages when `clerkMiddleware` is missing by suggesting the correct path to place the `middleware.ts` file.

packages/nextjs/src/app-router/server/ClerkProvider.tsx

@@ -7,6 +7,7 @@ import { getDynamicAuthData } from '../../server/buildClerkProps';
 import type { NextClerkProviderProps } from '../../types';
 import { canUseKeyless } from '../../utils/feature-flags';
 import { mergeNextClerkPropsWithEnv } from '../../utils/mergeNextClerkPropsWithEnv';
+import { onlyTry } from '../../utils/only-try';
 import { isNext13 } from '../../utils/sdk-versions';
 import { ClientClerkProvider } from '../client/ClerkProvider';
 import { deleteKeylessAction } from '../keyless-actions';
@@ -23,15 +24,6 @@ const getNonceFromCSPHeader = React.cache(async function getNonceFromCSPHeader()
   return getScriptNonceFromHeader((await headers()).get('Content-Security-Policy') || '') || '';
 });
 
-/** Discards errors thrown by attempted code */
-const onlyTry = (cb: () => unknown) => {
-  try {
-    cb();
-  } catch {
-    // ignore
-  }
-};
-
 export async function ClerkProvider(
   props: Without<NextClerkProviderProps, '__unstable_invokeMiddlewareOnAuthStateChange'>,
 ) {

packages/nextjs/src/app-router/server/auth.ts

@@ -3,12 +3,13 @@ import { constants, createClerkRequest, createRedirect, type RedirectFun } from
 import { notFound, redirect } from 'next/navigation';
 
 import { PUBLISHABLE_KEY, SIGN_IN_URL, SIGN_UP_URL } from '../../server/constants';
-import { createGetAuth } from '../../server/createGetAuth';
+import { createAsyncGetAuth } from '../../server/createGetAuth';
 import { authAuthHeaderMissing } from '../../server/errors';
 import { getAuthKeyFromRequest, getHeader } from '../../server/headers-utils';
 import type { AuthProtect } from '../../server/protect';
 import { createProtect } from '../../server/protect';
 import { decryptClerkRequestData } from '../../server/utils';
+import { isNextWithUnstableServerActions } from '../../utils/sdk-versions';
 import { buildRequestLike } from './utils';
 
 /**
@@ -25,8 +26,10 @@ type Auth = AuthObject & {
    */
   redirectToSignIn: RedirectFun<ReturnType<typeof redirect>>;
 };
+
 export interface AuthFn {
   (): Promise<Auth>;
+
   /**
    * `auth` includes a single property, the `protect()` method, which you can use in two ways:
    * - to check if a user is authenticated (signed in)
@@ -60,9 +63,22 @@ export const auth: AuthFn = async () => {
   require('server-only');
 
   const request = await buildRequestLike();
-  const authObject = createGetAuth({
+
+  const stepsBasedOnSrcDirectory = async () => {
+    if (isNextWithUnstableServerActions) {
+      return [];
+    }
+
+    try {
+      const isSrcAppDir = await import('../../server/keyless-node.js').then(m => m.hasSrcAppDir());
+      return [`Your Middleware exists at ./${isSrcAppDir ? 'src/' : ''}middleware.ts`];
+    } catch {
+      return [];
+    }
+  };
+  const authObject = await createAsyncGetAuth({
     debugLoggerName: 'auth()',
-    noAuthStatusMessage: authAuthHeaderMissing(),
+    noAuthStatusMessage: authAuthHeaderMissing('auth', await stepsBasedOnSrcDirectory()),
   })(request);
 
   const clerkUrl = getAuthKeyFromRequest(request, 'ClerkUrl');

packages/nextjs/src/app-router/server/utils.ts

@@ -34,7 +34,7 @@ export async function buildRequestLike(): Promise<NextRequest> {
     }
 
     throw new Error(
-      `Clerk: auth() and currentUser() are only supported in App Router (/app directory).\nIf you're using /pages, try getAuth() instead.\nOriginal error: ${e}`,
+      `Clerk: auth(), currentUser() and clerkClient(), are only supported in App Router (/app directory).\nIf you're using /pages, try getAuth() instead.\nOriginal error: ${e}`,
     );
   }
 }

packages/nextjs/src/server/__tests__/createGetAuth.test.ts

@@ -3,7 +3,7 @@ import hmacSHA1 from 'crypto-js/hmac-sha1';
 import { NextRequest } from 'next/server';
 import { describe, expect, it } from 'vitest';
 
-import { createGetAuth, getAuth } from '../createGetAuth';
+import { createSyncGetAuth, getAuth } from '../createGetAuth';
 
 const mockSecretKey = 'sk_test_mock';
 
@@ -16,7 +16,7 @@ const mockTokenSignature = hmacSHA1(mockToken, 'sk_test_mock').toString();
 
 describe('createGetAuth(opts)', () => {
   it('returns a getAuth function', () => {
-    expect(createGetAuth({ debugLoggerName: 'test', noAuthStatusMessage: 'test' })).toBeInstanceOf(Function);
+    expect(createSyncGetAuth({ debugLoggerName: 'test', noAuthStatusMessage: 'test' })).toBeInstanceOf(Function);
   });
 });
 

packages/nextjs/src/server/createGetAuth.ts

@@ -1,29 +1,63 @@
-import type { AuthObject } from '@clerk/backend';
 import { constants } from '@clerk/backend/internal';
 import { isTruthy } from '@clerk/shared/underscore';
 
 import { withLogger } from '../utils/debugLogger';
+import { isNextWithUnstableServerActions } from '../utils/sdk-versions';
 import { getAuthDataFromRequest } from './data/getAuthDataFromRequest';
 import { getAuthAuthHeaderMissing } from './errors';
-import { getHeader } from './headers-utils';
+import { detectClerkMiddleware, getHeader } from './headers-utils';
 import type { RequestLike } from './types';
 import { assertAuthStatus } from './utils';
 
-export const createGetAuth = ({
+export const createAsyncGetAuth = ({
+  debugLoggerName,
   noAuthStatusMessage,
+}: {
+  debugLoggerName: string;
+  noAuthStatusMessage: string;
+}) =>
+  withLogger(debugLoggerName, logger => {
+    return async (req: RequestLike, opts?: { secretKey?: string }) => {
+      if (isTruthy(getHeader(req, constants.Headers.EnableDebug))) {
+        logger.enable();
+      }
+
+      if (!detectClerkMiddleware(req)) {
+        // Keep the same behaviour for versions that may have issues with bundling `node:fs`
+        if (isNextWithUnstableServerActions) {
+          assertAuthStatus(req, noAuthStatusMessage);
+        }
+
+        const missConfiguredMiddlewareLocation = await import('./keyless-node.js')
+          .then(m => m.suggestMiddlewareLocation())
+          .catch(() => undefined);
+
+        if (missConfiguredMiddlewareLocation) {
+          throw new Error(missConfiguredMiddlewareLocation);
+        }
+
+        // still throw there is no suggested move location
+        assertAuthStatus(req, noAuthStatusMessage);
+      }
+
+      return getAuthDataFromRequest(req, { ...opts, logger });
+    };
+  });
+
+export const createSyncGetAuth = ({
   debugLoggerName,
+  noAuthStatusMessage,
 }: {
   debugLoggerName: string;
   noAuthStatusMessage: string;
 }) =>
   withLogger(debugLoggerName, logger => {
-    return (req: RequestLike, opts?: { secretKey?: string }): AuthObject => {
+    return (req: RequestLike, opts?: { secretKey?: string }) => {
       if (isTruthy(getHeader(req, constants.Headers.EnableDebug))) {
         logger.enable();
       }
 
       assertAuthStatus(req, noAuthStatusMessage);
-
       return getAuthDataFromRequest(req, { ...opts, logger });
     };
   });
@@ -107,7 +141,7 @@ export const createGetAuth = ({
  * }
  * ```
  */
-export const getAuth = createGetAuth({
+export const getAuth = createSyncGetAuth({
   debugLoggerName: 'getAuth()',
   noAuthStatusMessage: getAuthAuthHeaderMissing(),
 });

packages/nextjs/src/server/errors.ts

@@ -20,9 +20,9 @@ Check if signInUrl is missing from your configuration or if it is not an absolut
 
 export const getAuthAuthHeaderMissing = () => authAuthHeaderMissing('getAuth');
 
-export const authAuthHeaderMissing = (helperName = 'auth') =>
+export const authAuthHeaderMissing = (helperName = 'auth', prefixSteps?: string[]) =>
   `Clerk: ${helperName}() was called but Clerk can't detect usage of clerkMiddleware(). Please ensure the following:
--  clerkMiddleware() is used in your Next.js Middleware.
+- ${prefixSteps ? [...prefixSteps, ''].join('\n- ') : ' '}clerkMiddleware() is used in your Next.js Middleware.
 - Your Middleware matcher is configured to match this route or page.
 - If you are using the src directory, make sure the Middleware file is inside of it.
 

packages/nextjs/src/server/keyless-node.ts

@@ -209,4 +209,47 @@ function removeKeyless() {
   unlockFileWriting();
 }
 
-export { createOrReadKeyless, removeKeyless };
+function hasSrcAppDir() {
+  const { existsSync } = safeNodeRuntimeFs();
+  const path = safeNodeRuntimePath();
+
+  const projectWithAppSrc = path.join(process.cwd(), 'src', 'app');
+
+  return !!existsSync(projectWithAppSrc);
+}
+
+function suggestMiddlewareLocation() {
+  const suggestionMessage = (to?: 'src/', from?: 'src/app/' | 'app/') =>
+    `Clerk: Move your middleware file to ./${to || ''}middleware.ts. Currently located at ./${from || ''}middleware.ts`;
+
+  const { existsSync } = safeNodeRuntimeFs();
+  const path = safeNodeRuntimePath();
+
+  const projectWithAppSrcPath = path.join(process.cwd(), 'src', 'app');
+  const projectWithAppPath = path.join(process.cwd(), 'app');
+
+  if (existsSync(projectWithAppSrcPath)) {
+    if (existsSync(path.join(projectWithAppSrcPath, 'middleware.ts'))) {
+      return suggestionMessage('src/', 'src/app/');
+    }
+
+    if (existsSync(path.join(process.cwd(), 'middleware.ts'))) {
+      return suggestionMessage('src/');
+    }
+
+    // default error
+    return undefined;
+  }
+
+  if (existsSync(projectWithAppPath)) {
+    if (existsSync(path.join(projectWithAppPath, 'middleware.ts'))) {
+      return suggestionMessage(undefined, 'app/');
+    }
+    // default error
+    return undefined;
+  }
+
+  return undefined;
+}
+
+export { createOrReadKeyless, removeKeyless, suggestMiddlewareLocation, hasSrcAppDir };

packages/nextjs/src/utils/only-try.ts

@@ -0,0 +1,12 @@
+/**
+ * Discards errors thrown by attempted code
+ */
+const onlyTry = (cb: () => unknown) => {
+  try {
+    cb();
+  } catch {
+    // ignore
+  }
+};
+
+export { onlyTry };