vercel · kodiakhq · Jul 12, 2023 · Jul 12, 2023 · Jul 12, 2023 · Jul 12, 2023
@@ -1,13 +1,14 @@
 let installed: boolean = false
 
-export function loadWebpackHook() {
-  const { init: initWebpack } = require('next/dist/compiled/webpack/webpack')
-  if (installed) {
-    return
+export function loadWebpackHook({ init }: { init: boolean }) {
+  if (init) {
+    const { init: initWebpack } = require('next/dist/compiled/webpack/webpack')
+    if (installed) {
+      return
+    }
+    installed = true
+    initWebpack()
   }
-  installed = true
-
-  initWebpack()
 
   // hook the Node.js require so that webpack requires are
   // routed to the bundled and now initialized webpack version

@@ -725,8 +725,19 @@ export default async function loadConfig(
 
   await loadEnvConfig(dir, phase === PHASE_DEVELOPMENT_SERVER, curLog)
 
-  if (!process.env.__NEXT_PRIVATE_RENDER_WORKER) {
-    loadWebpackHook()
+  loadWebpackHook({
+    // For render workers, there's no need to init webpack eagerly
+    init: !process.env.__NEXT_PRIVATE_RENDER_WORKER,
+  })
+
+  // For the render worker, we directly return the serialized config from the
+  // parent worker (router worker) to avoid loading it again.
+  // This is because loading the config might be expensive especiall when people
+  // have Webpack plugins added.
+  // Because of this change, unserializable fields like `.webpack` won't be
+  // existing here but the render worker shouldn't use these as well.
+  if (process.env.__NEXT_PRIVATE_RENDER_WORKER_CONFIG) {
+    return JSON.parse(process.env.__NEXT_PRIVATE_RENDER_WORKER_CONFIG)
   }
 
   let configFileName = 'next.config.js'

@@ -1,4 +1,5 @@
 import type NextServer from '../../next-server'
+import type { NextConfigComplete } from '../../config-shared'
 
 import { getNodeOptionsWithoutInspect } from '../utils'
 import { deserializeErr, errorToJSON } from '../../render'
@@ -84,10 +85,11 @@ export const createWorker = async (
   ipcValidationKey: string,
   isNodeDebugging: boolean | 'brk' | undefined,
   type: 'pages' | 'app',
-  useServerActions?: boolean
+  nextConfig: NextConfigComplete
 ) => {
   const { initialEnv } = require('@next/env') as typeof import('@next/env')
   const { Worker } = require('next/dist/compiled/jest-worker')
+  const useServerActions = !!nextConfig.experimental.serverActions
 
   const worker = new Worker(require.resolve('../render-server'), {
     numWorkers: 1,
@@ -103,6 +105,7 @@ export const createWorker = async (
           .replace(/--max-old-space-size=[\d]{1,}/, '')
           .trim(),
         __NEXT_PRIVATE_RENDER_WORKER: type,
+        __NEXT_PRIVATE_RENDER_WORKER_CONFIG: JSON.stringify(nextConfig),
         __NEXT_PRIVATE_ROUTER_IPC_PORT: ipcPort + '',
         __NEXT_PRIVATE_ROUTER_IPC_KEY: ipcValidationKey,
         __NEXT_PRIVATE_STANDALONE_CONFIG:

@@ -290,14 +290,15 @@ export default class NextNodeServer extends BaseServer {
               ipcValidationKey,
               options.isNodeDebugging,
               'app',
-              this.nextConfig.experimental.serverActions
+              this.nextConfig
             )
           }
           this.renderWorkers.pages = await createWorker(
             ipcPort,
             ipcValidationKey,
             options.isNodeDebugging,
-            'pages'
+            'pages',
+            this.nextConfig
           )
           this.renderWorkers.middleware =
             this.renderWorkers.pages || this.renderWorkers.app

@@ -0,0 +1,7 @@
+export default function RootLayout({ children }) {
+  return (
+    <html lang="en">
+      <body>{children}</body>
+    </html>
+  )
+}
@@ -0,0 +1,3 @@
+export default function Home() {
+  return <h1>hello from page</h1>
+}
@@ -0,0 +1,15 @@
+import { createNextDescribe } from 'e2e-utils'
+
+createNextDescribe(
+  'app dir - next config',
+  {
+    files: __dirname,
+  },
+  ({ next }) => {
+    // https://github.com/vercel/next.js/issues/52366
+    it('should support importing webpack in next.config', async () => {
+      const html = await next.render('/')
+      expect(html).toContain('hello from page')
+    })
+  }
+)
@@ -0,0 +1,11 @@
+// This should work
+console.log(require('webpack').sources.RawSource)
+
+/** @type {import('next').NextConfig} */
+const nextConfig = {
+  webpack(config) {
+    return config
+  },
+}
+
+module.exports = nextConfig