Nuxt3: Missing sourcemaps if debugger is attached.

[ayalon]

Describe the bug
Debugging is not working with Nuxt3 if the debugger is attached.
But if the debugging process (server) is started from VSCode it works.

To Reproduce
Steps to reproduce the behavior:

1. Go to 'Reproduction repo debugdemo'
2. Follow the Readme to set it up
3. Attach the debugger, set a breakpoint: No hit
4. Start the project from VSCode, set a breakpoint, Works!

Configuration

{
    "configurations": [
        {
            "address": "localhost",
            "name": "Attach to local",
            "port": 9229,
            "request": "attach",
            "type": "node",
            "localRoot": "${workspaceFolder}",
            "remoteRoot": "${workspaceFolder}",
        },
        {
            "type": "node",
            "request": "launch",
            "name": "server: nuxt",
            "outputCapture": "std",
            "localRoot": "${workspaceFolder}",
            "program": "${workspaceFolder}/node_modules/nuxi/bin/nuxi.mjs",
            "args": [
                "dev"
            ],
            "outFiles": [
                "${workspaceFolder}/frontend/.nuxt/**/*",
            ]
        }
    ],
}

Log File

I analyzed the logfiles and the issue is, that the sourcemaps unter /.nuxt/dev are not loaded if the debugger is attached. If the debugging process is started from the terminal, these source maps can be found and the debugging works.

I'm super happy if someone could give me a hint how to use the "Attach" feature with Node with Nuxt3. As soon as I get this working, I could debug inside a docker container.

VS Code Version: 1.85.0

[connor4312]

This is a bug in Nuxt.js. When the main process is --inspect'ed, it will spawn its child with --inspect. But that listens on port 9229 by default, and if that port is in use (by the parent process listening on the same port, for example), the inspector fails to bind and it cannot be debugged.

https://github.com/nuxt/cli/blob/c448ade0ae58dff611bd01252c7ad10c76a805b6/src/commands/dev.ts#L171

When you start the process from VS Code, we don't pass in an --inspect flag (we use another mechanism to enable debugging) so it avoids the issue.

I suggest opening an issue on them for this.

[ayalon]

Thank you so much for your help @connor4312.
You took the time to understand my issue and pointed me to the exact source of the problem. I even was able understand and fix the issue and use the debugger now inside a container with that knowledge.
I created a blog post on our company website to share how to debug Nuxt 3.
https://www.liip.ch/en/blog/nuxt3-node-debugging

Credits to you for pointing me to the right direction!