[NEXT-1176] Debugging with non-localhost address stopped working

[gregmartyn]

Verify canary release

• I verified that the issue exists in the latest Next.js canary release

Provide environment information

Operating System:
      Platform: linux
      Arch: x64
      Version: #1 SMP PREEMPT_DYNAMIC Fri Mar  3 17:29:44 UTC 2023
    Binaries:
      Node: 17.9.0
      npm: 8.5.5
      Yarn: 1.22.19
      pnpm: N/A
    Relevant packages:
      next: 13.2.4
      eslint-config-next: 13.2.4
      react: 18.2.0
      react-dom: 18.2.0

Which area(s) of Next.js are affected? (leave empty if unsure)

CLI (create-next-app)

Link to the code that reproduces this issue

https://github.com/vercel/next.js/blame/8d83d85e5359146bbbd0f96ea2f8490e7d6bc9cd/packages/next/src/cli/next-dev.ts#L488

To Reproduce

NODE_OPTIONS=--inspect=0.0.0.0:9229 next dev

Describe the Bug

NodeJS's --inspect switch takes an optional address as a parameter that isn't being honored by Next. Next crashes when that is present.
spec: --inspect[=[host:]port]
https://nodejs.org/api/cli.html#--inspecthostport

In order to be able to expose a debugger from inside a Docker container, it has to listen on 0.0.0.0 instead of the default 127.0.0.1. To do that, we have to specify --inspect=0.0.0.0:9229.

https://github.com/vercel/next.js/blame/8d83d85e5359146bbbd0f96ea2f8490e7d6bc9cd/packages/next/src/cli/next-dev.ts#L488

assumes the parameter is an integer: parseInt(debugPortStr, 10), but debugPortStr could be e.g. 0.0.0.0:9229

https://github.com/vercel/next.js/blob/canary/packages/next/src/cli/next-dev.ts#L524
then does
--inspect${isDebuggingWithBrk ? '-brk' : ''}=${debugPort + 1}

which crashes:

warn  - the --inspect option was detected, the Next.js server should be inspected at port 1.
/usr/bin/node:  must be 0 or in range 1024 to 65535.

Expected Behavior

Next should parse out and honor the address part of the --inspect switch.

Which browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

Docker for local dev, Vercel for hosting

_NEXT-1176

[JackWatson06]

Thank you for posting this! You beat me to it. Was having this EXACT same issue yesterday.

[itsravenous]

I have this issue too (using e.g. --inspect=:9230). Curious, why does Next try to increment the port number?

[JackWatson06]

I have this issue too (using e.g. --inspect=:9230). Curious, why does Next try to increment the port number?

The dev server spawns a new child node.js process (which has been occurring since recent updates to Next.js) - as such, it increments the inspect debug port as it's different from the primary process which started next.js. This comment somewhat discusses this concept: https://github.com/vercel/next.js/pull/45745/files#r1101862213

[edorgeville]

@JackWatson06 points in the right direction.
This line more specifically:

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

Line 518 in 8b44085

return debugPortStr ? parseInt(debugPortStr, 10) : 9229

It expects debugPortStr to be shaped like an integer. But if you use --inspect:0.0.0.0:12345, debugPortStr is now 0.0.0.0:12345, thus the parse fails and returns 0.
Then not long after, it tries using this 0 port and does +1 on it.

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

Line 541 in 8b44085

`--inspect${isDebuggingWithBrk ? '-brk' : ''}=${debugPort + 1}`

Causing the /usr/bin/node: must be 0 or in range 1024 to 65535. error.

EDIT: woops, turns out @gregmartyn had already provided this explanation in the issue body 😅

[pirtlj]

I'm seeing this as well, using docker running

"dev": "NODE_OPTIONS=\"--inspect=0.0.0.0:9229\" next dev -p 3001",

and no longer hitting break points

I added the port to my docker-compose and it worked

ports:
- "3001:3001"
- "9229:9229"
- "9230:9230"

[Cow258]

13.2.4 is working well, but it not working on the latest Next.js canary release.

Expected(v13.2.4): both 9229 and 9230 should be used

Currently(v13.3.1-canary.0): only 9229 used, 9230 is missing

[Cow258]

Hi @huozhi,

If you have some spare time, would you be able to help me further with this issue?

Debugger is something I often use to quickly find problems,
but the latest release is not working for me and it's causing me some trouble.

Thank you.

[pirtlj]

I'm having this issue still 13.3.1 i'm using

NODE_OPTIONS=\"--inspect=0.0.0.0:9229\" next dev -p 3001

I'm also running in docker with

ports:
  - "3001:3001"
  - "9229:9229"
  - "9230:9230"

[gregmartyn]

@ijjk I don't see the fix addressing an inspect arg with an IP address like --inspect=0.0.0.0:9229

[github-actions]

This closed issue has been automatically locked because it had no new activity for a month. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.