From 81bbfe0c9a9fea27d110cc13f499c282a2673643 Mon Sep 17 00:00:00 2001
From: Vincent Voyer <vincent@codeagain.com>
Date: Fri, 13 Mar 2020 10:07:37 +0100
Subject: [PATCH 1/2] fix(debugging): do not pass NODE_OPTIONS='--inspect' to
 subprocesses

fixes #11030
---
 packages/next/server/next-dev-server.ts | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/packages/next/server/next-dev-server.ts b/packages/next/server/next-dev-server.ts
index a8450ca036891..ff97701a1f611 100644
--- a/packages/next/server/next-dev-server.ts
+++ b/packages/next/server/next-dev-server.ts
@@ -85,6 +85,16 @@ 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

From eaed6aba507edeb058124261ad7697b088375db4 Mon Sep 17 00:00:00 2001
From: Alec Larson <alec.stanford.larson@gmail.com>
Date: Sun, 15 Mar 2020 16:07:39 -0400
Subject: [PATCH 2/2] fix(debugger): use a regex to remove bad NODE_OPTIONS
 flags

---
 packages/next/server/lib/utils.ts       |  5 +++++
 packages/next/server/next-dev-server.ts |  1 +
 test/integration/cli/test/index.test.js | 10 ++++++++++
 3 files changed, 16 insertions(+)

diff --git a/packages/next/server/lib/utils.ts b/packages/next/server/lib/utils.ts
index f8f4ae1303496..e8830a9576610 100644
--- a/packages/next/server/lib/utils.ts
+++ b/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, '')
+}
diff --git a/packages/next/server/next-dev-server.ts b/packages/next/server/next-dev-server.ts
index ff97701a1f611..82c9dbeebfb7a 100644
--- a/packages/next/server/next-dev-server.ts
+++ b/packages/next/server/next-dev-server.ts
@@ -31,6 +31,7 @@ import ErrorDebug from './error-debug'
 import HotReloader from './hot-reloader'
 import { findPageFile } from './lib/find-page-file'
 import Worker from 'jest-worker'
+import { getNodeOptionsWithoutInspect } from './lib/utils'
 
 if (typeof React.Suspense === 'undefined') {
   throw new Error(
diff --git a/test/integration/cli/test/index.test.js b/test/integration/cli/test/index.test.js
index 9014b11b7911e..1265a915c58df 100644
--- a/test/integration/cli/test/index.test.js
+++ b/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)