Opt-into worker mode when appDir is enabled

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

@@ -371,6 +371,12 @@ const nextDev: CliCommand = async (argv) => {
             undefined,
             true
           )
+
+          if (config.experimental?.appDir && !devServerOptions.useWorkers) {
+            Log.error(
+              `Disabling dev workers is not supported with appDir enabled`
+            )
+          }
         }
       }
 

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

@@ -6,6 +6,9 @@ import { getPort, printAndExit } from '../server/lib/utils'
 import isError from '../lib/is-error'
 import { getProjectDir } from '../lib/get-project-dir'
 import { CliCommand } from '../lib/commands'
+import { resolve } from 'path'
+import { PHASE_PRODUCTION_SERVER } from '../shared/lib/constants'
+import loadConfig from '../server/config'
 
 const nextStart: CliCommand = async (argv) => {
   const validArgs: arg.Spec = {
@@ -71,13 +74,21 @@ const nextStart: CliCommand = async (argv) => {
     ? Math.ceil(keepAliveTimeoutArg)
     : undefined
 
+  const config = await loadConfig(
+    PHASE_PRODUCTION_SERVER,
+    resolve(dir || '.'),
+    undefined,
+    undefined,
+    true
+  )
+
   await startServer({
     dir,
     isDev: false,
     hostname: host,
     port,
     keepAliveTimeout,
-    useWorkers: false,
+    useWorkers: !!config.experimental.appDir,
   })
 }
 

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

@@ -5,6 +5,7 @@ import { getNodeOptionsWithoutInspect } from './utils'
 import type { IncomingMessage, ServerResponse } from 'http'
 import type { ChildProcess } from 'child_process'
 import { normalizeRepeatedSlashes } from '../../shared/lib/utils'
+import { initialEnv } from '@next/env'
 
 export interface StartServerOptions {
   dir: string
@@ -185,7 +186,7 @@ export async function startServer({
         forkOptions: {
           env: {
             FORCE_COLOR: '1',
-            ...process.env,
+            ...((initialEnv || process.env) as typeof process.env),
             // we don't pass down NODE_OPTIONS as it can
             // extra memory usage
             NODE_OPTIONS: getNodeOptionsWithoutInspect()
@@ -242,8 +243,9 @@ export async function startServer({
       didInitialize = true
 
       const getProxyServer = (pathname: string) => {
-        const targetUrl = `http://${targetHost}:${routerPort}${pathname}`
-
+        const targetUrl = `http://${
+          targetHost === 'localhost' ? '127.0.0.1' : targetHost
+        }:${routerPort}${pathname}`
         const proxyServer = httpProxy.createProxy({
           target: targetUrl,
           changeOrigin: false,
@@ -253,7 +255,7 @@ export async function startServer({
           followRedirects: false,
         })
 
-        proxyServer.on('error', () => {
+        proxyServer.on('error', (_err) => {
           // TODO?: enable verbose error logs with --debug flag?
         })
         return proxyServer

packages/next/src/server/next.ts

@@ -1,6 +1,8 @@
 import type { Options as DevServerOptions } from './dev/next-dev-server'
 import type { NodeRequestHandler } from './next-server'
 import type { UrlWithParsedQuery } from 'url'
+import type { NextConfigComplete } from './config-shared'
+
 import './node-polyfill-fetch'
 import { default as Server } from './next-server'
 import * as log from '../build/output/log'
@@ -29,7 +31,9 @@ const getServerImpl = async () => {
   return ServerImpl
 }
 
-export type NextServerOptions = Partial<DevServerOptions>
+export type NextServerOptions = Partial<DevServerOptions> & {
+  preloadedConfig?: NextConfigComplete
+}
 
 export interface RequestHandler {
   (
@@ -144,12 +148,15 @@ export class NextServer {
   }
 
   private async loadConfig() {
-    return loadConfig(
-      this.options.dev ? PHASE_DEVELOPMENT_SERVER : PHASE_PRODUCTION_SERVER,
-      resolve(this.options.dir || '.'),
-      this.options.conf,
-      undefined,
-      !!this.options._renderWorker
+    return (
+      this.options.preloadedConfig ||
+      loadConfig(
+        this.options.dev ? PHASE_DEVELOPMENT_SERVER : PHASE_PRODUCTION_SERVER,
+        resolve(this.options.dir || '.'),
+        this.options.conf,
+        undefined,
+        !!this.options._renderWorker
+      )
     )
   }
 

test/e2e/app-dir/app-static/app-static.test.ts

@@ -93,16 +93,19 @@ createNextDescribe(
         )
         expect((await revalidateRes.json()).revalidated).toBe(true)
 
-        const newRes = await next.fetch('/variable-revalidate/revalidate-360')
-        const newHtml = await newRes.text()
-        const new$ = cheerio.load(newHtml)
-        const newLayoutData = new$('#layout-data').text()
-        const newPageData = new$('#page-data').text()
-
-        expect(newLayoutData).toBeTruthy()
-        expect(newPageData).toBeTruthy()
-        expect(newLayoutData).not.toBe(initLayoutData)
-        expect(newPageData).not.toBe(initPageData)
+        await check(async () => {
+          const newRes = await next.fetch('/variable-revalidate/revalidate-360')
+          const newHtml = await newRes.text()
+          const new$ = cheerio.load(newHtml)
+          const newLayoutData = new$('#layout-data').text()
+          const newPageData = new$('#page-data').text()
+
+          expect(newLayoutData).toBeTruthy()
+          expect(newPageData).toBeTruthy()
+          expect(newLayoutData).not.toBe(initLayoutData)
+          expect(newPageData).not.toBe(initPageData)
+          return 'success'
+        }, 'success')
       })
     }
 

test/e2e/app-dir/app/index.test.ts

@@ -184,7 +184,7 @@ createNextDescribe(
       const res = await next.fetch('/dashboard')
       expect(res.headers.get('x-edge-runtime')).toBe('1')
       expect(res.headers.get('vary')).toBe(
-        isNextDeploy || isNextStart
+        isNextDeploy
           ? 'RSC, Next-Router-State-Tree, Next-Router-Prefetch'
           : 'RSC, Next-Router-State-Tree, Next-Router-Prefetch, Accept-Encoding'
       )

test/e2e/middleware-general/test/index.test.ts

@@ -484,22 +484,19 @@ describe('Middleware Runtime', () => {
     it('should contain process polyfill', async () => {
       const res = await fetchViaHTTP(next.url, `/global`)
       const json = readMiddlewareJSON(res)
-      delete json.process.env['JEST_WORKER_ID']
-
-      expect(json).toEqual({
-        process: {
-          env: {
-            ANOTHER_MIDDLEWARE_TEST: 'asdf2',
-            STRING_ENV_VAR: 'asdf3',
-            MIDDLEWARE_TEST: 'asdf',
-            ...((global as any).isNextDeploy
-              ? {}
-              : {
-                  NEXT_RUNTIME: 'edge',
-                }),
-          },
-        },
-      })
+
+      for (const [key, value] of Object.entries({
+        ANOTHER_MIDDLEWARE_TEST: 'asdf2',
+        STRING_ENV_VAR: 'asdf3',
+        MIDDLEWARE_TEST: 'asdf',
+        ...((global as any).isNextDeploy
+          ? {}
+          : {
+              NEXT_RUNTIME: 'edge',
+            }),
+      })) {
+        expect(json.process.env[key]).toBe(value)
+      }
     })
 
     it(`should contain \`globalThis\``, async () => {