Add flag to disable API warning

docs/api-routes/api-middlewares.md

@@ -56,6 +56,16 @@ export const config = {
 }
 ```
 
+`externalResolver` is an explicit flag that tells the server that this route is being handled by an external resolver like _express_ or _connect_. Enabling this option disables warnings for unresolved requests.
+
+```js
+export const config = {
+  api: {
+    externalResolver: true,
+  },
+}
+```
+
 ## Connect/Express middleware support
 
 You can also use [Connect](https://github.com/senchalabs/connect) compatible middleware.

packages/next/next-server/server/api-utils.ts

@@ -37,6 +37,7 @@ export async function apiResolver(
     }
     const config: PageConfig = resolverModule.config || {}
     const bodyParser = config.api?.bodyParser !== false
+    const externalResolver = config.api?.externalResolver || false
 
     // Parsing of cookies
     setLazyProp({ req: apiReq }, 'cookies', getCookieParser(req))
@@ -70,7 +71,12 @@ export async function apiResolver(
     // Call API route method
     await resolver(req, res)
 
-    if (process.env.NODE_ENV !== 'production' && !isResSent(res) && !wasPiped) {
+    if (
+      process.env.NODE_ENV !== 'production' &&
+      !externalResolver &&
+      !isResSent(res) &&
+      !wasPiped
+    ) {
       console.warn(
         `API resolved without sending a response for ${req.url}, this may result in stalled requests.`
       )

packages/next/types/index.d.ts

@@ -53,6 +53,12 @@ export type PageConfig = {
      * format supported by `bytes`, for example `1000`, `'500kb'` or `'3mb'`.
      */
     bodyParser?: { sizeLimit?: number | string } | false
+    /**
+     * Flag to disable warning "API page resolved
+     * without sending a response", due to explicitly
+     * using an external API resolver, like express
+     */
+    externalResolver?: true
   }
   env?: Array<string>
   unstable_runtimeJS?: false

test/integration/api-support/pages/api/external-resolver-false-positive.js

@@ -0,0 +1,5 @@
+export default (_req, res) => {
+  setTimeout(() => {
+    res.send('hello world')
+  }, 0)
+}

test/integration/api-support/pages/api/external-resolver.js

@@ -0,0 +1,11 @@
+export default (_req, res) => {
+  setTimeout(() => {
+    res.send('hello world')
+  }, 0)
+}
+
+export const config = {
+  api: {
+    externalResolver: true,
+  },
+}

test/integration/api-support/test/index.test.js

@@ -377,6 +377,25 @@ function runTests(dev = false) {
         `API resolved without sending a response for /api/test-res-pipe`
       )
     })
+
+    it('should show false positive warning if not using externalResolver flag', async () => {
+      const apiURL = '/api/external-resolver-false-positive'
+      const req = await fetchViaHTTP(appPort, apiURL)
+      expect(stderr).toContain(
+        `API resolved without sending a response for ${apiURL}, this may result in stalled requests.`
+      )
+      expect(await req.text()).toBe('hello world')
+    })
+
+    it('should not show warning if using externalResolver flag', async () => {
+      const startIdx = stderr.length > 0 ? stderr.length - 1 : stderr.length
+      const apiURL = '/api/external-resolver'
+      const req = await fetchViaHTTP(appPort, apiURL)
+      expect(stderr.substr(startIdx)).not.toContain(
+        `API resolved without sending a response for ${apiURL}`
+      )
+      expect(await req.text()).toBe('hello world')
+    })
   } else {
     it('should show warning with next export', async () => {
       const { stdout } = await nextExport(