Remove passing of NODE_OPTIONS='--inspect' to subprocesses (#11041)

* fix(debugging): do not pass NODE_OPTIONS='--inspect' to subprocesses

fixes #11030

* fix(debugger): use a regex to remove bad NODE_OPTIONS flags

Co-authored-by: Alec Larson <alec.stanford.larson@gmail.com>

packages/next/server/lib/utils.ts

@@ -8,3 +8,8 @@ export function printAndExit(message: string, code = 1) {
 
   process.exit(code)
 }
+
+export function getNodeOptionsWithoutInspect() {
+  const NODE_INSPECT_RE = /--inspect(-brk)?(=\S+)? ?/
+  return (process.env.NODE_OPTIONS || '').replace(NODE_INSPECT_RE, '')
+}

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

@@ -31,6 +31,7 @@ import { Telemetry } from '../telemetry/storage'
 import ErrorDebug from './error-debug'
 import HotReloader from './hot-reloader'
 import { findPageFile } from './lib/find-page-file'
+import { getNodeOptionsWithoutInspect } from './lib/utils'
 
 if (typeof React.Suspense === 'undefined') {
   throw new Error(
@@ -87,6 +88,16 @@ export default class DevServer extends Server {
       {
         maxRetries: 0,
         numWorkers: this.nextConfig.experimental.cpus,
+        forkOptions: {
+          env: {
+            ...process.env,
+            // discard --inspect/--inspect-brk flags from process.env.NODE_OPTIONS. Otherwise multiple Node.js debuggers
+            // would be started if user launch Next.js in debugging mode. The number of debuggers is linked to
+            // the number of workers Next.js tries to launch. The only worker users are interested in debugging
+            // is the main Next.js one
+            NODE_OPTIONS: getNodeOptionsWithoutInspect(),
+          },
+        },
       }
     ) as Worker & {
       loadStaticPaths: typeof import('./static-paths-worker').loadStaticPaths

test/integration/cli/test/index.test.js

@@ -88,6 +88,16 @@ describe('CLI Usage', () => {
       expect(output).toMatch(new RegExp(`http://localhost:${port}`))
     })
 
+    test("NODE_OPTIONS='--inspect'", async () => {
+      // this test checks that --inspect works by launching a single debugger for the main Next.js process,
+      // not for its subprocesses
+      const port = await findPort()
+      const output = await runNextCommandDev([dir, '--port', port], true, {
+        env: { NODE_OPTIONS: '--inspect' },
+      })
+      expect(output).toMatch(new RegExp(`ready on http://localhost:${port}`))
+    })
+
     test('-p', async () => {
       const port = await findPort()
       const output = await runNextCommandDev([dir, '-p', port], true)