feat(experimental): option to polyfill fetch using undici in Node.js <18 (#40318)

This PR adds a new `experimental.enableUndici` option to let the
developer switch from `next-fetch` to `undici` as the underlying
polyfill for `fetch` in Node.js.

In the current implementation, Next.js makes sure that `fetch` is always
available by using `node-fetch`. However, we do not polyfill in Node.js
18+, since those versions come with their own `fetch` implementation
already, built-in.

Node.js 18+ uses `undici` under the hood, so letting the developer use
`undici` earlier could make the migration easier later on.

Eventually, we hope to be able to stop polyfilling `fetch` in an
upcoming major version of Next.js, shipping less code.


## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the
feature request has been accepted for implementation before opening a
PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`

## Documentation / Examples

- [ ] Make sure the linting passes by running `pnpm lint`
- [ ] The examples guidelines are followed from [our contributing
doc](https://github.com/vercel/next.js/blob/canary/contributing.md#adding-examples)

Co-authored-by: Balázs Orbán <info@balazsorban.com>
Co-authored-by: Sukka <isukkaw@gmail.com>
Co-authored-by: JJ Kasper <jj@jjsweb.site>
Co-authored-by: Steven <steven@ceriously.com>

jest.config.js

@@ -3,6 +3,7 @@ const nextJest = require('next/jest')
 const createJestConfig = nextJest()
 
 // Any custom config you want to pass to Jest
+/** @type {import('jest').Config} */
 const customJestConfig = {
   testMatch: ['**/*.test.js', '**/*.test.ts', '**/*.test.tsx'],
   setupFilesAfterEnv: ['<rootDir>/jest-setup-after-env.ts'],
@@ -10,6 +11,9 @@ const customJestConfig = {
   rootDir: 'test',
   modulePaths: ['<rootDir>/lib'],
   transformIgnorePatterns: ['/next[/\\\\]dist/', '/\\.next/'],
+  globals: {
+    AbortSignal: global.AbortSignal,
+  },
 }
 
 // createJestConfig is exported in this way to ensure that next/jest can load the Next.js config which is async

packages/next/build/index.ts

@@ -1205,6 +1205,7 @@ export default async function build(
               configFileName,
               runtimeEnvConfig,
               httpAgentOptions: config.httpAgentOptions,
+              enableUndici: config.experimental.enableUndici,
               locales: config.i18n?.locales,
               defaultLocale: config.i18n?.defaultLocale,
               pageRuntime: config.experimental.runtime,
@@ -1352,6 +1353,7 @@ export default async function build(
                           configFileName,
                           runtimeEnvConfig,
                           httpAgentOptions: config.httpAgentOptions,
+                          enableUndici: config.experimental.enableUndici,
                           locales: config.i18n?.locales,
                           defaultLocale: config.i18n?.defaultLocale,
                           parentId: isPageStaticSpan.id,

packages/next/build/utils.ts

@@ -41,7 +41,7 @@ import {
   LoadComponentsReturnType,
 } from '../server/load-components'
 import { trace } from '../trace'
-import { setHttpAgentOptions } from '../server/config'
+import { setHttpClientAndAgentOptions } from '../server/config'
 import { recursiveDelete } from '../lib/recursive-delete'
 import { Sema } from 'next/dist/compiled/async-sema'
 import { MiddlewareManifest } from './webpack/plugins/middleware-plugin'
@@ -1169,6 +1169,7 @@ export async function isPageStatic({
   configFileName,
   runtimeEnvConfig,
   httpAgentOptions,
+  enableUndici,
   locales,
   defaultLocale,
   parentId,
@@ -1184,6 +1185,7 @@ export async function isPageStatic({
   configFileName: string
   runtimeEnvConfig: any
   httpAgentOptions: NextConfigComplete['httpAgentOptions']
+  enableUndici?: NextConfigComplete['experimental']['enableUndici']
   locales?: string[]
   defaultLocale?: string
   parentId?: any
@@ -1210,7 +1212,10 @@ export async function isPageStatic({
   return isPageStaticSpan
     .traceAsyncFn(async () => {
       require('../shared/lib/runtime-config').setConfig(runtimeEnvConfig)
-      setHttpAgentOptions(httpAgentOptions)
+      setHttpClientAndAgentOptions({
+        httpAgentOptions,
+        experimental: { enableUndici },
+      })
 
       let componentsResult: LoadComponentsReturnType
       let prerenderRoutes: Array<string> | undefined

packages/next/compiled/undici/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) Matteo Collina and Undici contributors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

packages/next/compiled/undici/package.json

@@ -0,0 +1 @@
+{"name":"undici","main":"index.js","author":"Matteo Collina <hello@matteocollina.com>","license":"MIT"}

packages/next/export/index.ts

@@ -619,6 +619,7 @@ export default async function exportApp(
             httpAgentOptions: nextConfig.httpAgentOptions,
             serverComponents: !!nextConfig.experimental.appDir,
             appPaths: options.appPaths || [],
+            enableUndici: nextConfig.experimental.enableUndici,
           })
 
           for (const validation of result.ampValidations || []) {

packages/next/export/worker.ts

@@ -23,7 +23,7 @@ import { requireFontManifest } from '../server/require'
 import { normalizeLocalePath } from '../shared/lib/i18n/normalize-locale-path'
 import { trace } from '../trace'
 import { isInAmpMode } from '../shared/lib/amp-mode'
-import { setHttpAgentOptions } from '../server/config'
+import { setHttpClientAndAgentOptions } from '../server/config'
 import RenderResult from '../server/render-result'
 import isError from '../lib/is-error'
 import { addRequestMeta } from '../server/request-meta'
@@ -70,6 +70,7 @@ interface ExportPageInput {
   httpAgentOptions: NextConfigComplete['httpAgentOptions']
   serverComponents?: boolean
   appPaths: string[]
+  enableUndici: NextConfigComplete['experimental']['enableUndici']
 }
 
 interface ExportPageResults {
@@ -119,8 +120,12 @@ export default async function exportPage({
   disableOptimizedLoading,
   httpAgentOptions,
   serverComponents,
+  enableUndici,
 }: ExportPageInput): Promise<ExportPageResults> {
-  setHttpAgentOptions(httpAgentOptions)
+  setHttpClientAndAgentOptions({
+    httpAgentOptions,
+    experimental: { enableUndici },
+  })
   const exportPageSpan = trace('export-page-worker', parentSpanId)
 
   return exportPageSpan.traceAsyncFn(async () => {

packages/next/package.json

@@ -264,6 +264,7 @@
     "timers-browserify": "2.0.12",
     "tty-browserify": "0.0.1",
     "ua-parser-js": "0.7.28",
+    "undici": "5.10.0",
     "unistore": "3.4.1",
     "util": "0.12.4",
     "uuid": "8.3.2",

packages/next/server/config-schema.ts

@@ -390,6 +390,9 @@ const configSchema = {
           },
           type: 'array',
         },
+        enableUndici: {
+          type: 'boolean',
+        },
         workerThreads: {
           type: 'boolean',
         },

packages/next/server/config-shared.ts

@@ -146,6 +146,7 @@ export interface ExperimentalConfig {
    * [webpack/webpack#ModuleNotoundError.js#L13-L42](https://github.com/webpack/webpack/blob/2a0536cf510768111a3a6dceeb14cb79b9f59273/lib/ModuleNotFoundError.js#L13-L42)
    */
   fallbackNodePolyfills?: false
+  enableUndici?: boolean
   sri?: {
     algorithm?: SubresourceIntegrityAlgorithm
   }
@@ -585,6 +586,7 @@ export const defaultConfig: NextConfig = {
     amp: undefined,
     urlImports: undefined,
     modularizeImports: undefined,
+    enableUndici: false,
     adjustFontFallbacks: false,
   },
 }

packages/next/server/config-utils.ts

@@ -139,6 +139,7 @@ export function loadWebpackHook() {
         'next/dist/compiled/@babel/runtime/package.json',
       ],
       ['node-fetch', 'next/dist/compiled/node-fetch'],
+      ['undici', 'next/dist/compiled/undici'],
     ].map(
       // Use dynamic require.resolve to avoid statically analyzable since they're only for build time
       ([request, replacement]) => [request, require.resolve(replacement)]

packages/next/server/config.ts

@@ -13,6 +13,7 @@ import {
   ExperimentalConfig,
   NextConfigComplete,
   validateConfig,
+  NextConfig,
 } from './config-shared'
 import { loadWebpackHook } from './config-utils'
 import {
@@ -22,6 +23,7 @@ import {
 } from '../shared/lib/image-config'
 import { loadEnvConfig } from '@next/env'
 import { hasNextSupport } from '../telemetry/ci-info'
+import { gte as semverGte } from 'next/dist/compiled/semver'
 
 export { DomainLocale, NextConfig, normalizeConfig } from './config-shared'
 
@@ -45,12 +47,22 @@ const experimentalWarning = execOnce(
   }
 )
 
-export function setHttpAgentOptions(
-  options: NextConfigComplete['httpAgentOptions']
-) {
+export function setHttpClientAndAgentOptions(options: NextConfig) {
+  if (semverGte(process.version, '16.8.0')) {
+    if (semverGte(process.version, '18.0.0')) {
+      Log.warn(
+        '`enableUndici` option is unnecessary in Node.js v18.0.0 or greater.'
+      )
+    }
+    ;(global as any).__NEXT_USE_UNDICI = options.experimental?.enableUndici
+  } else if (options.experimental?.enableUndici) {
+    Log.warn(
+      '`enableUndici` option requires Node.js v16.8.0 or greater. Falling back to `node-fetch`'
+    )
+  }
   if ((global as any).__NEXT_HTTP_AGENT) {
     // We only need to assign once because we want
-    // to resuse the same agent for all requests.
+    // to reuse the same agent for all requests.
     return
   }
 
@@ -58,8 +70,9 @@ export function setHttpAgentOptions(
     throw new Error('Expected config.httpAgentOptions to be an object')
   }
 
-  ;(global as any).__NEXT_HTTP_AGENT = new HttpAgent(options)
-  ;(global as any).__NEXT_HTTPS_AGENT = new HttpsAgent(options)
+  ;(global as any).__NEXT_HTTP_AGENT_OPTIONS = options.httpAgentOptions
+  ;(global as any).__NEXT_HTTP_AGENT = new HttpAgent(options.httpAgentOptions)
+  ;(global as any).__NEXT_HTTPS_AGENT = new HttpsAgent(options.httpAgentOptions)
 }
 
 function assignDefaults(userConfig: { [key: string]: any }) {
@@ -545,9 +558,7 @@ function assignDefaults(userConfig: { [key: string]: any }) {
 
   // TODO: Change defaultConfig type to NextConfigComplete
   // so we don't need "!" here.
-  setHttpAgentOptions(
-    result.httpAgentOptions || defaultConfig.httpAgentOptions!
-  )
+  setHttpClientAndAgentOptions(result || defaultConfig)
 
   if (result.i18n) {
     const { i18n } = result
@@ -855,6 +866,6 @@ export default async function loadConfig(
   // reactRoot can be updated correctly even with no next.config.js
   const completeConfig = assignDefaults(defaultConfig) as NextConfigComplete
   completeConfig.configFileName = configFileName
-  setHttpAgentOptions(completeConfig.httpAgentOptions)
+  setHttpClientAndAgentOptions(completeConfig)
   return completeConfig
 }

packages/next/server/dev/next-dev-server.ts

@@ -1286,6 +1286,7 @@ export default class DevServer extends Server {
         publicRuntimeConfig,
         serverRuntimeConfig,
         httpAgentOptions,
+        experimental: { enableUndici },
       } = this.nextConfig
       const { locales, defaultLocale } = this.nextConfig.i18n || {}
 
@@ -1299,6 +1300,7 @@ export default class DevServer extends Server {
           serverRuntimeConfig,
         },
         httpAgentOptions,
+        enableUndici,
         locales,
         defaultLocale,
         originalAppPath,

packages/next/server/dev/static-paths-worker.ts

@@ -7,7 +7,7 @@ import {
   collectGenerateParams,
 } from '../../build/utils'
 import { loadComponents } from '../load-components'
-import { setHttpAgentOptions } from '../config'
+import { setHttpClientAndAgentOptions } from '../config'
 
 type RuntimeConfig = any
 
@@ -22,6 +22,7 @@ export async function loadStaticPaths({
   serverless,
   config,
   httpAgentOptions,
+  enableUndici,
   locales,
   defaultLocale,
   isAppPath,
@@ -32,6 +33,7 @@ export async function loadStaticPaths({
   serverless: boolean
   config: RuntimeConfig
   httpAgentOptions: NextConfigComplete['httpAgentOptions']
+  enableUndici: NextConfigComplete['enableUndici']
   locales?: string[]
   defaultLocale?: string
   isAppPath?: boolean
@@ -49,7 +51,10 @@ export async function loadStaticPaths({
 
   // update work memory runtime-config
   require('../../shared/lib/runtime-config').setConfig(config)
-  setHttpAgentOptions(httpAgentOptions)
+  setHttpClientAndAgentOptions({
+    httpAgentOptions,
+    experimental: { enableUndici },
+  })
 
   const components = await loadComponents({
     distDir,

packages/next/server/node-polyfill-fetch.js

@@ -1,23 +1,56 @@
-import fetch, {
-  Headers,
-  Request,
-  Response,
-} from 'next/dist/compiled/node-fetch'
-
 // Polyfill fetch() in the Node.js environment
+
 if (!global.fetch) {
-  const agent = ({ protocol }) =>
-    protocol === 'http:' ? global.__NEXT_HTTP_AGENT : global.__NEXT_HTTPS_AGENT
-  const fetchWithAgent = (url, opts, ...rest) => {
-    if (!opts) {
-      opts = { agent }
-    } else if (!opts.agent) {
-      opts.agent = agent
-    }
-    return fetch(url, opts, ...rest)
+  function getFetchImpl() {
+    return global.__NEXT_USE_UNDICI
+      ? require('next/dist/compiled/undici')
+      : require('next/dist/compiled/node-fetch')
   }
-  global.fetch = fetchWithAgent
-  global.Headers = Headers
-  global.Request = Request
-  global.Response = Response
+  // Due to limitation of global configuration, we have to do this resolution at runtime
+  global.fetch = (...args) => {
+    const fetchImpl = getFetchImpl()
+
+    if (global.__NEXT_USE_UNDICI) {
+      // Undici does not support the `keepAlive` option,
+      // instead we have to pass a custom dispatcher
+      if (
+        !global.__NEXT_HTTP_AGENT_OPTIONS?.keepAlive &&
+        !global.__NEXT_UNDICI_AGENT_SET
+      ) {
+        global.__NEXT_UNDICI_AGENT_SET = true
+        fetchImpl.setGlobalDispatcher(new fetchImpl.Agent({ pipelining: 0 }))
+      }
+      return fetchImpl.fetch(...args)
+    }
+    const agent = ({ protocol }) =>
+      protocol === 'http:'
+        ? global.__NEXT_HTTP_AGENT
+        : global.__NEXT_HTTPS_AGENT
+
+    if (!args[1]) {
+      args[1] = { agent }
+    } else if (!args[1].agent) {
+      args[1].agent = agent
+    }
+
+    return fetchImpl(...args)
+  }
+
+  Object.defineProperties(global, {
+    Headers: {
+      get() {
+        return getFetchImpl().Headers
+      },
+    },
+    Request: {
+      get() {
+        return getFetchImpl().Request
+      },
+    },
+    Response: {
+      get() {
+        return getFetchImpl().Response
+      },
+    },
+  })
 }

packages/next/taskfile.js

@@ -86,6 +86,8 @@ const externals = {
     'next/dist/build/webpack/plugins/terser-webpack-plugin',
 
   // TODO: Add @swc/helpers to externals once @vercel/ncc switch to swc-loader
+
+  undici: 'undici',
 }
 // eslint-disable-next-line camelcase
 externals['node-html-parser'] = 'next/dist/compiled/node-html-parser'
@@ -167,6 +169,14 @@ export async function ncc_node_fetch(task, opts) {
     .target('compiled/node-fetch')
 }
 
+externals['undici'] = 'next/dist/compiled/undici'
+export async function ncc_undici(task, opts) {
+  await task
+    .source(opts.src || relative(__dirname, require.resolve('undici')))
+    .ncc({ packageName: 'undici', externals })
+    .target('compiled/undici')
+}
+
 // eslint-disable-next-line camelcase
 export async function compile_config_schema(task, opts) {
   const { configSchema } = require('./dist/server/config-schema')
@@ -1818,6 +1828,7 @@ export async function ncc(task, opts) {
         'ncc_get_orientation',
         'ncc_hapi_accept',
         'ncc_node_fetch',
+        'ncc_undici',
         'ncc_acorn',
         'ncc_amphtml_validator',
         'ncc_arg',

packages/next/types/misc.d.ts

@@ -28,6 +28,8 @@ declare module 'next/dist/compiled/node-fetch' {
   export * from 'node-fetch'
 }
 
+declare module 'next/dist/compiled/undici' {}
+
 declare module 'next/dist/compiled/jest-worker' {
   export * from 'jest-worker'
 }

pnpm-lock.yaml

@@ -601,6 +601,7 @@ importers:
       timers-browserify: 2.0.12
       tty-browserify: 0.0.1
       ua-parser-js: 0.7.28
+      undici: 5.10.0
       unistore: 3.4.1
       use-sync-external-store: 1.2.0
       util: 0.12.4
@@ -789,6 +790,7 @@ importers:
       timers-browserify: 2.0.12
       tty-browserify: 0.0.1
       ua-parser-js: 0.7.28
+      undici: 5.10.0
       unistore: 3.4.1
       util: 0.12.4
       uuid: 8.3.2
@@ -3896,7 +3898,7 @@ packages:
         integrity: sha512-OoUX2+yhtBH6FGtPoI3gP0YQfjDyLWUzifuvZ3cZwF8AF8Gs7DWM9Lg8/9OfhP4I9ZL8DAuK+hSwxOKdvOLXew==,
       }
     dependencies:
-      '@edge-runtime/vm': 1.1.0-beta.33
+      '@edge-runtime/vm': 1.1.0-beta.34
       '@jest/environment': 28.1.3
       '@jest/fake-timers': 28.1.3
       '@jest/types': 28.1.3
@@ -3911,15 +3913,6 @@ packages:
       }
     dev: true
 
-  /@edge-runtime/vm/1.1.0-beta.33:
-    resolution:
-      {
-        integrity: sha512-Aifd/elNDeI01oEzUnCF5URPtMgBIVDhnuy/F6SgS2OMJvzts/U5Rl2hxYliViU2OpC8ZkM/XT/t+Q7rQPJsgw==,
-      }
-    dependencies:
-      '@edge-runtime/primitives': 1.1.0-beta.34
-    dev: true
-
   /@edge-runtime/vm/1.1.0-beta.34:
     resolution:
       {
@@ -4346,13 +4339,6 @@ packages:
       purgecss: 1.4.2
     dev: true
 
-  /@gar/promisify/1.1.3:
-    resolution:
-      {
-        integrity: sha512-k2Ty1JcVojjJFwrg/ThKi2ujJ7XNLYaFGNB/bWT9wGR+oSMJHMa5w+CUq6p/pVrKeNNgA7pCqEcjSnHVoqJQFw==,
-      }
-    dev: true
-
   /@grpc/grpc-js/0.8.1:
     resolution:
       {
@@ -5280,7 +5266,7 @@ packages:
       fs-extra: 9.1.0
       npm-package-arg: 8.1.0
       npmlog: 4.1.2
-      signal-exit: 3.0.7
+      signal-exit: 3.0.3
       write-pkg: 4.0.0
     dev: true
 
@@ -5789,16 +5775,6 @@ packages:
       }
     dev: true
 
-  /@npmcli/fs/1.1.1:
-    resolution:
-      {
-        integrity: sha512-8KG5RD0GVP4ydEzRn/I4BNDuxDtqVbOdm8675T49OIG/NGhaK0pjPX7ZcDlvKYbA+ulvVK3ztfcF4uBdOxuJbQ==,
-      }
-    dependencies:
-      '@gar/promisify': 1.1.3
-      semver: 7.3.7
-    dev: true
-
   /@npmcli/git/2.0.4:
     resolution:
       {
@@ -8267,7 +8243,7 @@ packages:
     dependencies:
       acorn: 7.4.1
 
-  /acorn-jsx/5.3.1_acorn@8.8.0:
+  /acorn-jsx/5.3.1_acorn@8.6.0:
     resolution:
       {
         integrity: sha512-K0Ptm/47OKfQRpNQ2J/oIN/3QYiK6FwW+eJbILhsdxh2WTLdl+30o8aGdTbm5JbffpFFAg/g+zi1E+jvJha5ng==,
@@ -8275,7 +8251,7 @@ packages:
     peerDependencies:
       acorn: ^6.0.0 || ^7.0.0 || ^8.0.0
     dependencies:
-      acorn: 8.8.0
+      acorn: 8.6.0
     dev: true
 
   /acorn-walk/7.1.1:
@@ -9988,14 +9964,13 @@ packages:
     engines: { node: '>= 0.8' }
     dev: true
 
-  /cacache/15.3.0:
+  /cacache/15.0.5:
     resolution:
       {
-        integrity: sha512-VVdYzXEn+cnbXpFgWs5hTT7OScegHVmLhJIR8Ufqk3iFD6A6j5iSX1KuBTfNEv4tdJWE2PzA6IVFtcLC7fN9wQ==,
+        integrity: sha512-lloiL22n7sOjEEXdL8NAjTgv9a1u43xICE9/203qonkZUCj5X1UEWIdf2/Y0d6QcCtMzbKQyhrcDbdvlZTs/+A==,
       }
     engines: { node: '>= 10' }
     dependencies:
-      '@npmcli/fs': 1.1.1
       '@npmcli/move-file': 1.0.1
       chownr: 2.0.0
       fs-minipass: 2.1.0
@@ -11074,7 +11049,10 @@ packages:
     dev: true
 
   /concat-map/0.0.1:
-    resolution: { integrity: sha1-2Klr13/Wjfd5OnMDajug1UBdR3s= }
+    resolution:
+      {
+        integrity: sha512-/Srv4dswyQNBfohGpz9o6Yb3Gz3SrUDqBH5rTuhGR7ahtlbYKnVxw2bCFMRljaA7EXHaXZ8wsHdodFvbkhKmqg==,
+      }
 
   /concat-stream/1.6.2:
     resolution:
@@ -13246,10 +13224,7 @@ packages:
     dev: true
 
   /err-code/1.1.2:
-    resolution:
-      {
-        integrity: sha512-CJAN+O0/yA1CKfRn9SXOGctSpEM7DCon/r/5r2eXFMY2zCCJBasFhcM5I+1kh3Ap11FsQCX+vGHceNPvpWKhoA==,
-      }
+    resolution: { integrity: sha1-BuARbTAo9q70gGhJ6w6mp0iuaWA= }
     dev: true
 
   /err-code/2.0.3:
@@ -14127,7 +14102,7 @@ packages:
       merge-stream: 2.0.0
       npm-run-path: 4.0.1
       onetime: 5.1.2
-      signal-exit: 3.0.7
+      signal-exit: 3.0.3
       strip-final-newline: 2.0.0
     dev: true
 
@@ -15112,10 +15087,10 @@ packages:
       console-control-strings: 1.1.0
       has-unicode: 2.0.1
       object-assign: 4.1.1
-      signal-exit: 3.0.7
+      signal-exit: 3.0.3
       string-width: 1.0.2
       strip-ansi: 3.0.1
-      wide-align: 1.1.5
+      wide-align: 1.1.3
     dev: true
 
   /generic-names/2.0.1:
@@ -16702,10 +16677,7 @@ packages:
     engines: { node: '>=0.8.19' }
 
   /indent-string/2.1.0:
-    resolution:
-      {
-        integrity: sha512-aqwDFWSgSgfRaEwao5lg5KEcVd/2a+D1rvoG7NdilmYz0NwRk6StWpWdz/Hpk34MKPpx7s8XxUqimfcQK6gGlg==,
-      }
+    resolution: { integrity: sha1-ji1INIdCEhtKghi3oTfppSBJ3IA= }
     engines: { node: '>=0.10.0' }
     dependencies:
       repeating: 2.0.1
@@ -18747,7 +18719,7 @@ packages:
         optional: true
     dependencies:
       abab: 2.0.5
-      acorn: 8.8.0
+      acorn: 8.6.0
       acorn-globals: 6.0.0
       cssom: 0.4.4
       cssstyle: 2.3.0
@@ -19195,10 +19167,7 @@ packages:
     dev: true
 
   /levn/0.3.0:
-    resolution:
-      {
-        integrity: sha512-0OO4y2iOHix2W6ujICbKIaEQXvFQHue65vUG3pb5EUomzPI90z9hsA1VsO/dbIIpC53J8gxM9Q4Oho0jrCM/yA==,
-      }
+    resolution: { integrity: sha1-OwmSTt+fCDwEkP3UwLxEIeBHZO4= }
     engines: { node: '>= 0.8.0' }
     dependencies:
       prelude-ls: 1.1.2
@@ -19816,7 +19785,7 @@ packages:
     engines: { node: '>=0.10.0' }
     dependencies:
       currently-unhandled: 0.4.1
-      signal-exit: 3.0.7
+      signal-exit: 3.0.3
     dev: true
 
   /lower-case-first/1.0.2:
@@ -19939,7 +19908,7 @@ packages:
     engines: { node: '>= 10' }
     dependencies:
       agentkeepalive: 4.1.4
-      cacache: 15.3.0
+      cacache: 15.0.5
       http-cache-semantics: 4.1.0
       http-proxy-agent: 4.0.1
       https-proxy-agent: 5.0.0
@@ -20198,10 +20167,7 @@ packages:
     dev: true
 
   /meow/3.7.0:
-    resolution:
-      {
-        integrity: sha512-TNdwZs0skRlpPpCUK25StC4VH+tP5GgeY1HQOOGP+lQ2xtdkN2VtT/5tiX9k3IWpkBPV9b3LsAWXn4GGi/PrSA==,
-      }
+    resolution: { integrity: sha1-cstmi0JSKCkKu/qFaJJYcwioAfs= }
     engines: { node: '>=0.10.0' }
     dependencies:
       camelcase-keys: 2.1.0
@@ -20423,8 +20389,8 @@ packages:
         integrity: sha512-NQuiYA0lw+eFDtSG4+c7ao3RG9dM4P0Kx/sn8OLyPhxtIc6k+9n14k5VfLxRKfAxYRTo8c5PLZPaRNmslGWxJw==,
       }
     dependencies:
-      acorn: 8.8.0
-      acorn-jsx: 5.3.1_acorn@8.8.0
+      acorn: 8.6.0
+      acorn-jsx: 5.3.1_acorn@8.6.0
       micromark: 2.11.4
       micromark-extension-mdx-expression: 0.3.2
       micromark-extension-mdx-jsx: 0.3.3
@@ -22222,7 +22188,7 @@ packages:
       '@npmcli/installed-package-contents': 1.0.7
       '@npmcli/promise-spawn': 1.3.2
       '@npmcli/run-script': 1.8.3
-      cacache: 15.3.0
+      cacache: 15.0.5
       chownr: 2.0.0
       fs-minipass: 2.1.0
       infer-owner: 1.0.4
@@ -23961,10 +23927,7 @@ packages:
     dev: true
 
   /prelude-ls/1.1.2:
-    resolution:
-      {
-        integrity: sha512-ESF23V4SKG6lVSGZgYNpbsiaAkdab6ZgOxe52p7+Kid3W3u3bxR4Vfd/o21dmN7jSt0IwgZ4v5MUd26FEtXE9w==,
-      }
+    resolution: { integrity: sha1-IZMqVJ9eUv/ZqCf1cOBL5iqX2lQ= }
     engines: { node: '>= 0.8.0' }
     dev: true
 
@@ -24111,10 +24074,7 @@ packages:
     dev: true
 
   /process-nextick-args/1.0.7:
-    resolution:
-      {
-        integrity: sha512-yN0WQmuCX63LP/TMvAg31nvT6m4vDqJEiiv2CAZqWOGNWutc9DfDk1NPYYmKUFmaVM2UwDowH4u5AHWYP/jxKw==,
-      }
+    resolution: { integrity: sha1-FQ4gt1ZZCtP5EJPyWk8q2L/zC6M= }
     dev: true
 
   /process-nextick-args/2.0.1:
@@ -24163,10 +24123,7 @@ packages:
     dev: true
 
   /promise-retry/1.1.1:
-    resolution:
-      {
-        integrity: sha512-StEy2osPr28o17bIW776GtwO6+Q+M9zPiZkYfosciUUMYqjhU/ffwRAH0zN2+uvGyUsn8/YICIHRzLbPacpZGw==,
-      }
+    resolution: { integrity: sha1-ZznpaOMFHaIM5kl/srUPaRHfPW0= }
     engines: { node: '>=0.12' }
     dependencies:
       err-code: 1.1.2
@@ -24773,10 +24730,7 @@ packages:
     dev: true
 
   /read-pkg-up/1.0.1:
-    resolution:
-      {
-        integrity: sha512-WD9MTlNtI55IwYUS27iHh9tK3YoIVhxis8yKhLpTqWtml739uXc9NWTpxoHkfZf3+DkCCsXox94/VWZniuZm6A==,
-      }
+    resolution: { integrity: sha1-nWPBMnbAZZGNV/ACpX9AobZD+wI= }
     engines: { node: '>=0.10.0' }
     dependencies:
       find-up: 1.1.2
@@ -24792,10 +24746,7 @@ packages:
     dev: true
 
   /read-pkg-up/3.0.0:
-    resolution:
-      {
-        integrity: sha512-YFzFrVvpC6frF1sz8psoHDBGF7fLPc+llq/8NB43oagqWkx8ar5zYtsTORtOjw9W2RHLpWP+zTWwBvf1bCmcSw==,
-      }
+    resolution: { integrity: sha1-PtSWaF26D4/hGNBpHcUfSh/5bwc= }
     engines: { node: '>=4' }
     dependencies:
       find-up: 2.1.0
@@ -24872,10 +24823,7 @@ packages:
     dev: true
 
   /readable-stream/1.1.14:
-    resolution:
-      {
-        integrity: sha512-+MeVjFf4L44XUkhM1eYbD8fyEsxcV81pqMSR5gblfcLCHfZvbrqy4/qYHE+/R5HoBUT11WV5O08Cr1n3YXkWVQ==,
-      }
+    resolution: { integrity: sha1-fPTFTvZI44EwhMY23SB54WbAgdk= }
     dependencies:
       core-util-is: 1.0.2
       inherits: 2.0.4
@@ -24990,10 +24938,7 @@ packages:
     dev: true
 
   /redent/1.0.0:
-    resolution:
-      {
-        integrity: sha512-qtW5hKzGQZqKoh6JNSD+4lfitfPKGz42e6QwiRmPM5mmKtR0N41AbJRYu0xJi7nhOJ4WDgRkKvAk6tw4WIwR4g==,
-      }
+    resolution: { integrity: sha1-z5Fqsf1fHxbfsggi3W7H9zDCr94= }
     engines: { node: '>=0.10.0' }
     dependencies:
       indent-string: 2.1.0
@@ -25453,7 +25398,10 @@ packages:
     dev: true
 
   /replace-ext/1.0.0:
-    resolution: { integrity: sha1-3mMSg3P8v3w8z6TeWkgMRaZ5WOs= }
+    resolution:
+      {
+        integrity: sha512-vuNYXC7gG7IeVNBC1xUllqCcZKRbJoSPOBhnTEcAIiKCsbuef6zO3F0Rve3isPMMoNoQRWjQwbAgAjHUHniyEA==,
+      }
     engines: { node: '>= 0.10' }
     dev: true
 
@@ -25501,10 +25449,7 @@ packages:
     dev: true
 
   /require-directory/2.1.1:
-    resolution:
-      {
-        integrity: sha512-fGxEI7+wsG9xrvdjsrlmL22OMTTiHRwAMroiEeMgq8gzoLC/PQr7RsRDSTLUg/bZAZtF+TVIkHc6/4RIKrui+Q==,
-      }
+    resolution: { integrity: sha1-jGStX9MNqxyXbiNE/+f3kqam30I= }
     engines: { node: '>=0.10.0' }
     dev: true
 
@@ -25647,7 +25592,7 @@ packages:
     engines: { node: '>=4' }
     dependencies:
       onetime: 2.0.1
-      signal-exit: 3.0.7
+      signal-exit: 3.0.3
     dev: true
 
   /restore-cursor/3.1.0:
@@ -25658,7 +25603,7 @@ packages:
     engines: { node: '>=8' }
     dependencies:
       onetime: 5.1.2
-      signal-exit: 3.0.7
+      signal-exit: 3.0.3
 
   /restore-cursor/4.0.0:
     resolution:
@@ -25668,7 +25613,7 @@ packages:
     engines: { node: ^12.20.0 || ^14.13.1 || >=16.0.0 }
     dependencies:
       onetime: 5.1.2
-      signal-exit: 3.0.7
+      signal-exit: 3.0.3
     dev: true
 
   /ret/0.1.15:
@@ -26422,6 +26367,7 @@ packages:
       {
         integrity: sha512-wnD2ZE+l+SPC/uoS0vXeE9L1+0wuaMqKlfz9AMUo38JsyLSBWSFcHR1Rri62LZc12vLr1gb3jl7iwQhgwpAbGQ==,
       }
+    dev: true
 
   /simple-swizzle/0.2.2:
     resolution:
@@ -26474,10 +26420,7 @@ packages:
     dev: true
 
   /slice-ansi/0.0.4:
-    resolution:
-      {
-        integrity: sha512-up04hB2hR92PgjpyU3y/eg91yIBILyjVY26NvvciY3EVVPjybkMszMpXQ9QAkcS3I5rtJBDLoTxxg+qvW8c7rw==,
-      }
+    resolution: { integrity: sha1-7b+JA/ZvfOL46v1s7tZeJkyDGzU= }
     engines: { node: '>=0.10.0' }
     dev: true
 
@@ -28121,10 +28064,7 @@ packages:
     dev: true
 
   /trim-newlines/1.0.0:
-    resolution:
-      {
-        integrity: sha512-Nm4cF79FhSTzrLKGDMi3I4utBtFv8qKy4sq1enftf2gMdpqI8oVQTAfySkTz5r49giVzDj88SVZXP4CeYQwjaw==,
-      }
+    resolution: { integrity: sha1-WIeWa7WCpFA6QetST301ARgVphM= }
     engines: { node: '>=0.10.0' }
     dev: true
 
@@ -28331,10 +28271,7 @@ packages:
     dev: true
 
   /type-check/0.3.2:
-    resolution:
-      {
-        integrity: sha512-ZCmOJdvOWDBYJlzAoFkC+Q0+bUyEOS1ltgp1MGU03fqHG+dbi9tBFU2Rd9QKiDZFAYrhPh2JUf7rZRIuHRKtOg==,
-      }
+    resolution: { integrity: sha1-WITKtRLPHTVeP7eE8wgEsrUg23I= }
     engines: { node: '>= 0.8.0' }
     dependencies:
       prelude-ls: 1.1.2
@@ -28535,6 +28472,14 @@ packages:
     engines: { node: '>=0.10.0' }
     dev: true
 
+  /undici/5.10.0:
+    resolution:
+      {
+        integrity: sha512-c8HsD3IbwmjjbLvoZuRI26TZic+TSEe8FPMLLOkN1AfYRhdjnKBU6yL+IwcSCbdZiX4e5t0lfMDLDCqj4Sq70g==,
+      }
+    engines: { node: '>=12.18' }
+    dev: true
+
   /unfetch/4.1.0:
     resolution:
       {
@@ -29260,7 +29205,10 @@ packages:
     dev: true
 
   /verror/1.10.0:
-    resolution: { integrity: sha1-OhBcoXBTr1XW4nDB+CiGguGNpAA= }
+    resolution:
+      {
+        integrity: sha512-ZZKSmDAEFOijERBLkmYfJ+vmk3w+7hOLYDNkRCuRuMJGEmqYNCNLyBBFwWKVMhfwaEF3WOd0Zlw86U/WC/+nYw==,
+      }
     engines: { '0': node >=0.6.0 }
     dependencies:
       assert-plus: 1.0.0
@@ -29761,13 +29709,13 @@ packages:
     dependencies:
       isexe: 2.0.0
 
-  /wide-align/1.1.5:
+  /wide-align/1.1.3:
     resolution:
       {
-        integrity: sha512-eDMORYaPNZ4sQIuuYPDHdQvf4gyCF9rEEV/yPxGfwPkRodwEgiMUUXTx/dex+Me0wxx53S+NgUHaP7y3MGlDmg==,
+        integrity: sha512-QGkOQc8XL6Bt5PwnsExKBPuMKBxnGxWWW3fU55Xt4feHozMUhdUMaBCk290qpm/wG5u/RSKzwdAC4i51YigihA==,
       }
     dependencies:
-      string-width: 4.2.3
+      string-width: 2.1.1
     dev: true
 
   /widest-line/3.1.0:
@@ -29792,10 +29740,7 @@ packages:
     dev: true
 
   /wrap-ansi/3.0.1:
-    resolution:
-      {
-        integrity: sha512-iXR3tDXpbnTpzjKSylUJRkLuOrEC7hwEB221cgn6wtF8wpmz28puFXAEfPT5zrjM3wahygB//VuWEr1vTkDcNQ==,
-      }
+    resolution: { integrity: sha1-KIoE2H7aXChuBg3+jxNc6NAH+Lo= }
     engines: { node: '>=4' }
     dependencies:
       string-width: 2.1.1
@@ -29861,7 +29806,7 @@ packages:
     dependencies:
       imurmurhash: 0.1.4
       is-typedarray: 1.0.0
-      signal-exit: 3.0.3
+      signal-exit: 3.0.7
       typedarray-to-buffer: 3.1.5
     dev: true
 

test/e2e/undici-fetch/index.test.ts

@@ -0,0 +1,129 @@
+import { createNext } from 'e2e-utils'
+import { NextInstance } from 'test/lib/next-modes/base'
+import { fetchViaHTTP } from 'next-test-utils'
+import semver from 'semver'
+
+if (
+  semver.lt(process.version, '16.8.0') ||
+  semver.gte(process.version, '18.0.0')
+) {
+  it('skipping for Node.js versions <16.8.0 and >18.0.0', () => {
+    expect(true).toBe(true)
+  })
+} else {
+  describe('undici fetch', () => {
+    let next: NextInstance
+
+    beforeAll(async () => {
+      next = await createNext({
+        files: {
+          'pages/api/globalFetch.js': `
+            import { ReadableStream } from 'node:stream/web';
+            export default async function globalFetch(req, res) {
+              try {
+                const response = await fetch('https://example.vercel.sh')
+                res.json({ value: response.body instanceof ReadableStream })
+              } catch (error) {
+                console.error(error);
+                res.send(error);
+              }
+            }
+          `,
+          'pages/api/globalHeaders.js': `
+            export default async function globalHeaders(req, res) {
+              res.json({
+                value: (new Headers())[Symbol.iterator].name === 'entries'
+              })
+            }
+          `,
+          'pages/api/globalRequest.js': `
+            export default async function globalRequest(req, res) {
+              res.json({
+                value: (new Request('https://example.vercel.sh')).headers[Symbol.iterator].name === 'entries'
+              })
+            }
+          `,
+          'pages/api/globalResponse.js': `
+            export default async function globalResponse(req, res) {
+              res.json({
+                value: (new Response()).headers[Symbol.iterator].name === 'entries'
+              })
+            }
+          `,
+        },
+        dependencies: {},
+        nextConfig: {
+          experimental: {
+            enableUndici: true,
+          },
+        },
+      })
+    })
+    afterAll(() => next.destroy())
+
+    describe('undici', () => {
+      it('global fetch should return true when undici is used', async () => {
+        const result = await fetchViaHTTP(next.url, '/api/globalFetch')
+        const data = await result.json()
+        expect(data.value).toBe(true)
+      })
+
+      it('global Headers should return true when undici is used', async () => {
+        const result = await fetchViaHTTP(next.url, '/api/globalHeaders')
+        const data = await result.json()
+        expect(data.value).toBe(true)
+      })
+
+      it('global Request should return true when undici is used', async () => {
+        const result = await fetchViaHTTP(next.url, '/api/globalRequest')
+        const data = await result.json()
+        expect(data.value).toBe(true)
+      })
+
+      it('global Response should return true when undici is used', async () => {
+        const result = await fetchViaHTTP(next.url, '/api/globalResponse')
+        const data = await result.json()
+        expect(data.value).toBe(true)
+      })
+    })
+
+    describe('node-fetch', () => {
+      beforeAll(async () => {
+        await next.stop()
+        await next.patchFile(
+          'next.config.js',
+          `module.exports = ${JSON.stringify({
+            experimental: {
+              enableUndici: false,
+            },
+          })}`
+        )
+        await next.start()
+      })
+
+      it('global fetch should return false when node-fetch is used', async () => {
+        const result = await fetchViaHTTP(next.url, '/api/globalFetch')
+        const data = await result.json()
+        expect(data.value).toBe(false)
+      })
+
+      it('global Headers should return false when node-fetch is used', async () => {
+        const result = await fetchViaHTTP(next.url, '/api/globalHeaders')
+        const data = await result.json()
+        expect(data.value).toBe(false)
+      })
+
+      it('global Request should return false when node-fetch is used', async () => {
+        const result = await fetchViaHTTP(next.url, '/api/globalRequest')
+        const data = await result.json()
+        expect(data.value).toBe(false)
+      })
+
+      it('global Response should return false when node-fetch is used', async () => {
+        const result = await fetchViaHTTP(next.url, '/api/globalResponse')
+        const data = await result.json()
+        expect(data.value).toBe(false)
+      })
+    })
+  })
+}

test/integration/undici-keep-alive/next.config.js

@@ -0,0 +1,5 @@
+module.exports = {
+  experimental: {
+    enableUndici: true,
+  },
+}

test/integration/undici-keep-alive/pages/api/json.js

@@ -0,0 +1,5 @@
+export default async function handler(_req, res) {
+  const fetchRes = await fetch('http://localhost:44001')
+  const props = await fetchRes.json()
+  res.json(props)
+}

test/integration/undici-keep-alive/pages/blog/[slug].js

@@ -0,0 +1,23 @@
+export default function Blog(props) {
+  return <pre id="props">{JSON.stringify(props)}</pre>
+}
+
+export async function getStaticProps({ params: { slug } }) {
+  return { props: { slug } }
+}
+
+export async function getStaticPaths() {
+  const res = await fetch('http://localhost:44001')
+  const obj = await res.json()
+  if (obj.connection === 'keep-alive') {
+    return {
+      paths: [{ params: { slug: 'first' } }],
+      fallback: false,
+    }
+  }
+
+  return {
+    paths: [],
+    fallback: false,
+  }
+}

test/integration/undici-keep-alive/pages/ssg.js

@@ -0,0 +1,9 @@
+export default function SSG(props) {
+  return <pre id="props">{JSON.stringify(props)}</pre>
+}
+
+export async function getStaticProps() {
+  const res = await fetch('http://localhost:44001')
+  const props = await res.json()
+  return { props }
+}

test/integration/undici-keep-alive/pages/ssr.js

@@ -0,0 +1,9 @@
+export default function SSR(props) {
+  return <pre id="props">{JSON.stringify(props)}</pre>
+}
+
+export async function getServerSideProps() {
+  const res = await fetch('http://localhost:44001')
+  const props = await res.json()
+  return { props }
+}

test/integration/undici-keep-alive/test/index.test.js

@@ -0,0 +1,99 @@
+/* eslint-env jest */
+
+import { join } from 'path'
+import { createServer } from 'http'
+import {
+  fetchViaHTTP,
+  nextBuild,
+  findPort,
+  nextStart,
+  launchApp,
+  killApp,
+} from 'next-test-utils'
+import webdriver from 'next-webdriver'
+
+const appDir = join(__dirname, '../')
+
+let appPort
+let app
+let mockServer
+
+describe('undici-keep-alive', () => {
+  describe('dev', () => {
+    beforeAll(async () => {
+      mockServer = createServer((req, res) => {
+        // we can test request headers by sending them
+        // back with the response
+        const { connection } = req.headers
+        res.end(JSON.stringify({ connection }))
+      })
+      mockServer.listen(44001)
+      appPort = await findPort()
+      app = await launchApp(appDir, appPort)
+    })
+    afterAll(async () => {
+      await killApp(app)
+      mockServer.close()
+    })
+
+    runTests()
+  })
+
+  describe('production', () => {
+    beforeAll(async () => {
+      mockServer = createServer((req, res) => {
+        // we can test request headers by sending them
+        // back with the response
+        const { connection } = req.headers
+        res.end(JSON.stringify({ connection }))
+      })
+      mockServer.listen(44001)
+      const { stdout, stderr } = await nextBuild(appDir, [], {
+        stdout: true,
+        stderr: true,
+      })
+      if (stdout) console.log(stdout)
+      if (stderr) console.error(stderr)
+      appPort = await findPort()
+      app = await nextStart(appDir, appPort)
+    })
+    afterAll(async () => {
+      await killApp(app)
+      mockServer.close()
+    })
+
+    runTests()
+  })
+
+  function runTests() {
+    it('should send keep-alive for json API', async () => {
+      const res = await fetchViaHTTP(appPort, '/api/json')
+      const obj = await res.json()
+      expect(obj).toEqual({ connection: 'keep-alive' })
+    })
+
+    it('should send keep-alive for getStaticProps', async () => {
+      const browser = await webdriver(appPort, '/ssg')
+      const props = await browser.elementById('props').text()
+      const obj = JSON.parse(props)
+      expect(obj).toEqual({ connection: 'keep-alive' })
+      await browser.close()
+    })
+
+    it('should send keep-alive for getStaticPaths', async () => {
+      const browser = await webdriver(appPort, '/blog/first')
+      const props = await browser.elementById('props').text()
+      const obj = JSON.parse(props)
+      expect(obj).toEqual({ slug: 'first' })
+      await browser.close()
+    })
+
+    it('should send keep-alive for getServerSideProps', async () => {
+      const browser = await webdriver(appPort, '/ssr')
+      const props = await browser.elementById('props').text()
+      const obj = JSON.parse(props)
+      expect(obj).toEqual({ connection: 'keep-alive' })
+      await browser.close()
+    })
+  }
+})