Add API config to allow disabling response size warning

docs/api-routes/api-middlewares.md

@@ -68,6 +68,30 @@ export const config = {
 }
 ```
 
+`bodyLimit` is automatically enabled, warning when an API routes' response is over 4MB. If you'd like to disable this warning, you can set this to false.
+
+A use case for disabling the `bodyLimit` warning is if you are deploying outside of the Vercel ecosystem, i/e AWS or self hosting.
+
+```js
+export const config = {
+  api: {
+    bodyLimit: false,
+  },
+}
+```
+
+`bodyLimit.sizeLimit` is the maximum response size before a warning is displayed.
+
+```js
+export const config = {
+  api: {
+    bodyLimit: {
+      sizeLimit: '30mb',
+    },
+  },
+}
+```
+
 ## Connect/Express middleware support
 
 You can also use [Connect](https://github.com/senchalabs/connect) compatible middleware.

packages/next/package.json

@@ -70,6 +70,7 @@
   },
   "dependencies": {
     "@next/env": "12.1.1-canary.1",
+    "bytes": "3.1.1",
     "caniuse-lite": "^1.0.30001283",
     "postcss": "8.4.5",
     "styled-jsx": "5.0.0",
@@ -132,6 +133,7 @@
     "@types/babel__generator": "7.6.2",
     "@types/babel__template": "7.4.0",
     "@types/babel__traverse": "7.11.0",
+    "@types/bytes": "3.1.1",
     "@types/ci-info": "2.0.0",
     "@types/compression": "0.0.36",
     "@types/content-disposition": "0.5.4",

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

@@ -82,6 +82,8 @@ export function checkIsManualRevalidate(
 export const COOKIE_NAME_PRERENDER_BYPASS = `__prerender_bypass`
 export const COOKIE_NAME_PRERENDER_DATA = `__next_preview_data`
 
+export const MAX_CONTENT_LENGTH = 4 * 1024 * 1024
+
 export const SYMBOL_PREVIEW_DATA = Symbol(COOKIE_NAME_PRERENDER_DATA)
 export const SYMBOL_CLEARED_COOKIES = Symbol(COOKIE_NAME_PRERENDER_BYPASS)
 

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

@@ -1,5 +1,6 @@
 import type { IncomingMessage, ServerResponse } from 'http'
 import type { NextApiRequest, NextApiResponse } from '../../shared/lib/utils'
+import bytes from 'bytes'
 import type { PageConfig } from 'next/types'
 import type { __ApiPreviewProps } from '.'
 import type { BaseNextRequest, BaseNextResponse } from '../base-http'
@@ -28,6 +29,7 @@ import {
   COOKIE_NAME_PRERENDER_BYPASS,
   COOKIE_NAME_PRERENDER_DATA,
   SYMBOL_PREVIEW_DATA,
+  MAX_CONTENT_LENGTH,
 } from './index'
 
 export function tryGetPreviewData(
@@ -172,6 +174,7 @@ export async function apiResolver(
     }
     const config: PageConfig = resolverModule.config || {}
     const bodyParser = config.api?.bodyParser !== false
+    const bodyLimit = config.api?.bodyLimit ?? true
     const externalResolver = config.api?.externalResolver || false
 
     // Parsing of cookies
@@ -198,6 +201,7 @@ export async function apiResolver(
     }
 
     let contentLength = 0
+    const maxContentLength = getMaxContentLength(bodyLimit)
     const writeData = apiRes.write
     const endResponse = apiRes.end
     apiRes.write = (...args: any[2]) => {
@@ -209,9 +213,11 @@ export async function apiResolver(
         contentLength += Buffer.byteLength(args[0] || '')
       }
 
-      if (contentLength >= 4 * 1024 * 1024) {
+      if (bodyLimit && contentLength >= maxContentLength) {
         console.warn(
-          `API response for ${req.url} exceeds 4MB. This will cause the request to fail in a future version. https://nextjs.org/docs/messages/api-routes-body-size-limit`
+          `API response for ${req.url} exceeds ${bytes.format(
+            maxContentLength
+          )}. API Routes are meant to respond quickly. https://nextjs.org/docs/messages/api-routes-body-size-limit`
         )
       }
 
@@ -484,3 +490,12 @@ function setPreviewData<T>(
   ])
   return res
 }
+
+function getMaxContentLength(
+  bodyLimit?: { sizeLimit?: number | string } | boolean
+) {
+  if (bodyLimit && typeof bodyLimit !== 'boolean' && bodyLimit.sizeLimit) {
+    return bytes.parse(bodyLimit.sizeLimit)
+  }
+  return MAX_CONTENT_LENGTH
+}

packages/next/types/index.d.ts

@@ -63,6 +63,12 @@ export type NextPage<P = {}, IP = P> = NextComponentType<NextPageContext, IP, P>
 export type PageConfig = {
   amp?: boolean | 'hybrid'
   api?: {
+    /**
+     * Configures or disables body size limit warning. Can take a number or
+     * any string format supported by `bytes`, for example `1000`, `'500kb'` or
+     * `'3mb'`.
+     */
+    bodyLimit?: { sizeLimit?: number | string } | boolean
     /**
      * The byte limit of the body. This is the number of bytes or any string
      * format supported by `bytes`, for example `1000`, `'500kb'` or `'3mb'`.

test/integration/api-support/pages/api/large-chunked-response.js

@@ -1,5 +1,5 @@
 export default (req, res) => {
-  for (let i = 0; i <= 5 * 1024 * 1024; i++) {
+  for (let i = 0; i <= 4 * 1024 * 1024; i++) {
     res.write('.')
   }
   res.end()

test/integration/api-support/pages/api/large-response-with-config-size.js

@@ -0,0 +1,12 @@
+export const config = {
+  api: {
+    bodyLimit: {
+      sizeLimit: '5mb',
+    },
+  },
+}
+
+export default (req, res) => {
+  let body = '.'.repeat(6 * 1024 * 1024)
+  res.send(body)
+}

test/integration/api-support/pages/api/large-response-with-config.js

@@ -0,0 +1,10 @@
+export const config = {
+  api: {
+    bodyLimit: false,
+  },
+}
+
+export default (req, res) => {
+  let body = '.'.repeat(4 * 1024 * 1024)
+  res.send(body)
+}

test/integration/api-support/pages/api/large-response.js

@@ -1,4 +1,4 @@
 export default (req, res) => {
-  let body = '.'.repeat(5 * 1024 * 1024)
+  let body = '.'.repeat(4 * 1024 * 1024)
   res.send(body)
 }

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

@@ -451,13 +451,32 @@ function runTests(dev = false) {
     let res = await fetchViaHTTP(appPort, '/api/large-response')
     expect(res.ok).toBeTruthy()
     expect(stderr).toContain(
-      'API response for /api/large-response exceeds 4MB. This will cause the request to fail in a future version.'
+      'API response for /api/large-response exceeds 4MB. API Routes are meant to respond quickly.'
     )
 
     res = await fetchViaHTTP(appPort, '/api/large-chunked-response')
     expect(res.ok).toBeTruthy()
     expect(stderr).toContain(
-      'API response for /api/large-chunked-response exceeds 4MB. This will cause the request to fail in a future version.'
+      'API response for /api/large-chunked-response exceeds 4MB. API Routes are meant to respond quickly.'
+    )
+  })
+
+  it('should not warn if response body is larger than 4MB with bodyLimit config = false', async () => {
+    let res = await fetchViaHTTP(appPort, '/api/large-response-with-config')
+    expect(res.ok).toBeTruthy()
+    expect(stderr).not.toContain(
+      'API response for /api/large-response-with-config exceeds 4MB. API Routes are meant to respond quickly.'
+    )
+  })
+
+  it('should warn with configured size if response body is larger than configured size', async () => {
+    let res = await fetchViaHTTP(
+      appPort,
+      '/api/large-response-with-config-size'
+    )
+    expect(res.ok).toBeTruthy()
+    expect(stderr).toContain(
+      'API response for /api/large-response-with-config-size exceeds 5MB. API Routes are meant to respond quickly.'
     )
   })
 

yarn.lock

@@ -4796,6 +4796,11 @@
   resolved "https://registry.yarnpkg.com/@types/braces/-/braces-3.0.1.tgz#5a284d193cfc61abb2e5a50d36ebbc50d942a32b"
   integrity sha512-+euflG6ygo4bn0JHtn4pYqcXwRtLvElQ7/nnjDu7iYG56H0+OhCd7d6Ug0IE3WcFpZozBKW2+80FUbv5QGk5AQ==
 
+"@types/bytes@3.1.1":
+  version "3.1.1"
+  resolved "https://registry.yarnpkg.com/@types/bytes/-/bytes-3.1.1.tgz#67a876422e660dc4c10a27f3e5bcfbd5455f01d0"
+  integrity sha512-lOGyCnw+2JVPKU3wIV0srU0NyALwTBJlVSx5DfMQOFuuohA8y9S8orImpuIQikZ0uIQ8gehrRjxgQC1rLRi11w==
+
 "@types/cacheable-request@^6.0.1":
   version "6.0.1"
   resolved "https://registry.yarnpkg.com/@types/cacheable-request/-/cacheable-request-6.0.1.tgz#5d22f3dded1fd3a84c0bbeb5039a7419c2c91976"
@@ -7049,6 +7054,11 @@ bytes@3.1.0, bytes@^3.0.0:
   version "3.1.0"
   resolved "https://registry.yarnpkg.com/bytes/-/bytes-3.1.0.tgz#f6cf7933a360e0588fa9fde85651cdc7f805d1f6"
 
+bytes@3.1.1:
+  version "3.1.1"
+  resolved "https://registry.yarnpkg.com/bytes/-/bytes-3.1.1.tgz#3f018291cb4cbad9accb6e6970bca9c8889e879a"
+  integrity sha512-dWe4nWO/ruEOY7HkUJ5gFt1DCFV9zPRoJr8pV0/ASQermOZjtq8jMjOprC0Kd10GLN+l7xaUPvxzJFWtxGu8Fg==
+
 cacache@^12.0.2:
   version "12.0.3"
   resolved "https://registry.yarnpkg.com/cacache/-/cacache-12.0.3.tgz#be99abba4e1bf5df461cd5a2c1071fc432573390"