chore: drop undici (#56899)

### What?

Note: This is not a breaking change, just removing some unused code.

### Why?

Since #56896 we don't need this, as Node.js 18+ has `fetch` exposed by default.

### How?

Depends on #56896, #56909

We already didn't load `fetch` if `globalThis` had it (ie. Node.js 18+ environments), and since we are dropping support for Node.js 16, these code paths should have no effect on runtime behavior.

packages/next/package.json

@@ -304,7 +304,6 @@
     "timers-browserify": "2.0.12",
     "tty-browserify": "0.0.1",
     "ua-parser-js": "1.0.35",
-    "undici": "5.26.3",
     "unistore": "3.4.1",
     "util": "0.12.4",
     "uuid": "8.3.2",

packages/next/src/build/templates/app-route.ts

@@ -1,5 +1,3 @@
-import '../../server/node-polyfill-headers'
-
 import {
   AppRouteRouteModule,
   type AppRouteRouteModuleOptions,

packages/next/src/build/utils.ts

@@ -18,7 +18,6 @@ import type { WebpackLayerName } from '../lib/constants'
 import type { AppPageModule } from '../server/future/route-modules/app-page/module'
 
 import '../server/require-hook'
-import '../server/node-polyfill-fetch'
 import '../server/node-polyfill-crypto'
 import '../server/node-environment'
 

packages/next/src/cli/next-info.ts

@@ -4,9 +4,6 @@ import os from 'os'
 import childProcess from 'child_process'
 
 import { bold, cyan, yellow } from '../lib/picocolors'
-const { fetch } = require('next/dist/compiled/undici') as {
-  fetch: typeof global.fetch
-}
 import type { CliCommand } from '../lib/commands'
 import { PHASE_INFO } from '../shared/lib/constants'
 import loadConfig from '../server/config'

packages/next/src/export/worker.ts

@@ -7,8 +7,6 @@ import type {
   WorkerRenderOpts,
 } from './types'
 
-// Polyfill fetch for the export worker.
-import '../server/node-polyfill-fetch'
 import '../server/node-polyfill-web-streams'
 import '../server/node-environment'
 

packages/next/src/lib/download-swc.ts

@@ -2,9 +2,6 @@ import fs from 'fs'
 import path from 'path'
 import * as Log from '../build/output/log'
 import tar from 'next/dist/compiled/tar'
-const { fetch } = require('next/dist/compiled/undici') as {
-  fetch: typeof global.fetch
-}
 const { WritableStream } = require('node:stream/web') as {
   WritableStream: typeof global.WritableStream
 }

packages/next/src/lib/mkcert.ts

@@ -4,10 +4,6 @@ import { getCacheDirectory } from './helpers/get-cache-directory'
 import * as Log from '../build/output/log'
 import { execSync } from 'child_process'
 
-const { fetch } = require('next/dist/compiled/undici') as {
-  fetch: typeof global.fetch
-}
-
 const MKCERT_VERSION = 'v1.4.4'
 
 export interface SelfSignedCertificate {

packages/next/src/lib/patch-incorrect-lockfile.ts

@@ -1,5 +1,4 @@
 import { promises } from 'fs'
-import '../server/node-polyfill-fetch'
 import * as Log from '../build/output/log'
 import findUp from 'next/dist/compiled/find-up'
 // @ts-ignore no-json types

packages/next/src/server/app-render/action-handler.ts

@@ -423,10 +423,10 @@ export async function handleAction({
           } else {
             // React doesn't yet publish a busboy version of decodeAction
             // so we polyfill the parsing of FormData.
-            const UndiciRequest = require('next/dist/compiled/undici').Request
-            const fakeRequest = new UndiciRequest('http://localhost', {
+            const fakeRequest = new Request('http://localhost', {
               method: 'POST',
-              headers: { 'Content-Type': req.headers['content-type'] },
+              // @ts-expect-error
+              headers: { 'Content-Type': contentType },
               body: nodeToWebReadableStream(req),
               duplex: 'half',
             })

packages/next/src/server/config-utils.ts

@@ -136,7 +136,6 @@ export function loadWebpackHook() {
         '@babel/runtime/package.json',
         'next/dist/compiled/@babel/runtime/package.json',
       ],
-      ['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/src/server/dev/static-paths-worker.ts

@@ -1,7 +1,6 @@
 import type { NextConfigComplete } from '../config-shared'
 
 import '../require-hook'
-import '../node-polyfill-fetch'
 import '../node-environment'
 
 import {

packages/next/src/server/lib/mock-request.test.ts

@@ -1,8 +1,5 @@
 import { MockedRequest, MockedResponse } from './mock-request'
 
-// We use `Headers` here which is provided by the polyfill.
-import '../node-polyfill-fetch'
-
 describe('MockedRequest', () => {
   it('should have the correct properties', () => {
     const req = new MockedRequest({

packages/next/src/server/lib/route-resolver.ts

@@ -3,7 +3,6 @@ import type { IncomingMessage, ServerResponse } from 'http'
 import type { RenderServer } from './router-server'
 
 import '../require-hook'
-import '../node-polyfill-fetch'
 
 import url from 'url'
 import path from 'path'

packages/next/src/server/lib/router-server.ts

@@ -3,7 +3,6 @@ import type { WorkerRequestHandler, WorkerUpgradeHandler } from './types'
 import type { DevBundler } from './router-utils/setup-dev-bundler'
 import type { NextUrlWithParsedQuery } from '../request-meta'
 // This is required before other imports to ensure the require hook is setup.
-import '../node-polyfill-fetch'
 import '../node-environment'
 import '../require-hook'
 

packages/next/src/server/lib/start-server.ts

@@ -2,7 +2,6 @@ if (performance.getEntriesByName('next-start').length === 0) {
   performance.mark('next-start')
 }
 import '../next'
-import '../node-polyfill-fetch'
 import '../require-hook'
 
 import type { IncomingMessage, ServerResponse } from 'http'

packages/next/src/server/next-server.ts

@@ -1,6 +1,5 @@
 import './node-environment'
 import './require-hook'
-import './node-polyfill-fetch'
 import './node-polyfill-form'
 import './node-polyfill-web-streams'
 import './node-polyfill-crypto'

packages/next/src/server/next.ts

@@ -10,7 +10,6 @@ import type { NextUrlWithParsedQuery } from './request-meta'
 import type { WorkerRequestHandler, WorkerUpgradeHandler } from './lib/types'
 
 import './require-hook'
-import './node-polyfill-fetch'
 import './node-polyfill-crypto'
 
 import type { default as Server } from './next-server'

packages/next/src/server/web/spec-extension/adapters/headers.test.ts

@@ -1,8 +1,5 @@
 import type { IncomingHttpHeaders } from 'http'
 
-// We use `Headers` here which is provided by the polyfill.
-import '../../../node-polyfill-fetch'
-
 import { HeadersAdapter, ReadonlyHeadersError } from './headers'
 
 describe('HeadersAdapter', () => {

packages/next/src/server/web/spec-extension/adapters/request-cookies.test.ts

@@ -1,6 +1,3 @@
-// We use `Headers` here which is provided by the polyfill.
-import '../../../node-polyfill-fetch'
-
 import { RequestCookies } from '../cookies'
 import {
   ReadonlyRequestCookiesError,

packages/next/src/server/web/utils.test.ts

@@ -1,8 +1,5 @@
 import { toNodeOutgoingHttpHeaders } from './utils'
 
-// We use `Headers` here which is provided by the polyfill.
-import '../node-polyfill-fetch'
-
 describe('toNodeHeaders', () => {
   it('should handle multiple set-cookie headers correctly', () => {
     const headers = new Headers()

packages/next/src/telemetry/post-payload.ts

@@ -1,7 +1,4 @@
 import retry from 'next/dist/compiled/async-retry'
-const { fetch } = require('next/dist/compiled/undici') as {
-  fetch: typeof global.fetch
-}
 
 export function _postPayload(endpoint: string, body: object, signal?: any) {
   if (!signal && 'timeout' in AbortSignal) {

packages/next/taskfile.js

@@ -76,8 +76,6 @@ 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'
@@ -321,22 +319,6 @@ export async function ncc_node_platform(task, opts) {
   )
 }
 
-externals['undici'] = 'next/dist/compiled/undici'
-export async function ncc_undici(task, opts) {
-  await task
-    .source(relative(__dirname, require.resolve('undici')))
-    .ncc({ packageName: 'undici', externals })
-    .target('src/compiled/undici')
-
-  const outputFile = join('src/compiled/undici/index.js')
-  await fs.writeFile(
-    outputFile,
-    (
-      await fs.readFile(outputFile, 'utf8')
-    ).replace(/process\.emitWarning/g, 'void')
-  )
-}
-
 // eslint-disable-next-line camelcase
 externals['acorn'] = 'next/dist/compiled/acorn'
 export async function ncc_acorn(task, opts) {
@@ -2239,7 +2221,6 @@ export async function ncc(task, opts) {
         'ncc_node_cssescape',
         'ncc_node_platform',
         'ncc_node_shell_quote',
-        'ncc_undici',
         'ncc_acorn',
         'ncc_amphtml_validator',
         'ncc_arg',

packages/next/types/misc.d.ts

@@ -67,8 +67,6 @@ declare module 'next/dist/compiled/@mswjs/interceptors/ClientRequest' {
   export * from '@mswjs/interceptors/ClientRequest'
 }
 
-declare module 'next/dist/compiled/undici' {}
-
 declare module 'next/dist/compiled/jest-worker' {
   export * from 'jest-worker'
 }

test/unit/web-runtime/next-server-node.test.ts

@@ -1,5 +1,3 @@
-import 'next/dist/server/node-polyfill-fetch'
-
 it('should be able to require next/server outside edge', () => {
   require('next/server')
 })