Vscode-remote-release: Random high ports forwarded when debugging django with launcher

[floatingpurr]

• VSCode Version: 1.52.1
• Local OS Version: macOS 10.15.7
• Remote OS Version: Debian GNU/Linux 10 (buster)
• Remote Extension/Connection Type: Docker

Excuse me if the following shouldn't be a bug, but it seems pretty weird to me.

I'm using VSCode remote development to run and debug a django project inside a Docker container with VSCode server in it. In my devcontainer.json I forwarded the port 8000. When I start the debug, I see 4 ports forwarded: port 8000 and other 3 rendom high ports e.g.,:

8000 -> localhost:8000 (the only one I'd expect to see)
34075 -> 127.0.0.1:34075
37301 -> 127.0.0.1:37301
42129 -> 127.0.0.1:42129

Other ports are automatically forwarded if I restart the debug process.
I'm wondering the reason why those extra ports are forwarded and how I can avoid it.

Steps to Reproduce:

1. in devcontainer.json "forwardPorts": [8000],
2. Create a launch.json like the following

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python: Django",
            "type": "python",
            "request": "launch",
            "program": "${workspaceFolder}/manage.py",
            "args": [
                "runserver",
                "0.0.0.0:8000"
            ],
            "django": true
        }
    ]
}

1. Debug a Django project

Does this issue occur when you try this locally?: No
Does this issue occur when you try this locally and all extensions are disabled?: No

[niccolomineo]

I am observing the same behaviour and am wondering the same.

[chrmarti]

1.52 detects open ports and forwards them. You can turn this off in the settings either globally in the user settings or in the devcontainer.json using the "settings" property:

    "settings": { 
        "remote.autoForwardPorts": false
    },

[floatingpurr]

Thanx @chrmarti for pointing this out. Just a side question about this topic: why does VSCode open those ports after launching the debugger. I mean, this is my launch.json

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python: Django",
            "type": "python",
            "request": "launch",
            "program": "${workspaceFolder}/manage.py",
            "args": [
                "runserver",
                "0.0.0.0:8000"
            ],
            "django": true
        }
    ]
}

Before the debug:

vscode ➜ /workspace (main) $ netstat -ltnp 
(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 127.0.0.11:37389        0.0.0.0:*               LISTEN      -                   
tcp        0      0 0.0.0.0:5432            0.0.0.0:*               LISTEN      -                   
tcp        0      0 0.0.0.0:8000            0.0.0.0:*               LISTEN      1235/python         
tcp6       0      0 :::37463                :::*                    LISTEN      105/node            
tcp6       0      0 :::5432     

During the debug:

vscode ➜ /workspace/web (main) netstat -ltnp 
(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 127.0.0.1:44325         0.0.0.0:*               LISTEN      2156/python         
tcp        0      0 127.0.0.11:37389        0.0.0.0:*               LISTEN      -                   
tcp        0      0 127.0.0.1:44949         0.0.0.0:*               LISTEN      2156/python         
tcp        0      0 0.0.0.0:5432            0.0.0.0:*               LISTEN      -                   
tcp        0      0 127.0.0.1:40637         0.0.0.0:*               LISTEN      2156/python         
tcp        0      0 0.0.0.0:8000            0.0.0.0:*               LISTEN      2396/python         
tcp6       0      0 :::37463                :::*                    LISTEN      105/node            
tcp6       0      0 :::5432                 :::*                    LISTEN      - 

(ports 40637, 44325, 44949 are opened and then forwarded if autoForwardPorts is enabled)

Such ports aren't opened if a launch python manage.py runserver 0.0.0.0:8000 from the command line. I think it is a behavior somehow related to VSCode. Am I right?

[chrmarti]

These ports are probably from the python's debugger. Not sure why there would be 3 ports for that.