VS Code Remote Debugging Python in a Docker container

Question

I am using VS Code's "Remove - WSL" extension to try to connect to a Docker container (backed by WSL2) running a Python job.

The python job is started somewhat like this:

exec python3 -m debugpy --listen 5678 --wait-for-client some_file.py

In my docker-compose.yml file I have set

ports:
  - "5678:5678"

And I run the service with

docker-compose up

My VS Code launch.json contains the following:

    {
        "name": "Python: Remote Attach",
        "type": "python",
        "request": "attach",
        "connect": {
            "host": "localhost",
            "port": 5678
        },
        "pathMappings": [
            {
                "localRoot": "/home/myname/tensorflow_models/research",
                "remoteRoot": "/home/tensorflow/models/research"
            }
        ]
    }

However, running the above task briefly opens the debug bar and then closes it with no error message.

When I exec into the container I can run netcat localhost 5678 and it will return json. However, it doesn't return anything when I run the same from WSL:

netcat localhost 5678

or on Windows from powershell:

powercat -c localhost -p 5678

Or even from within the container using the container's ip:

# Manually get ip address
ip a
# Doesn't return anything
netcat <ip> 5678

xdhmoore · Accepted Answer · 2020-12-05 06:55:18Z

2

The problem was that by default debugpy only listens on localhost (local connections only). The solution was to set the listen address to 0.0.0.0 (all addresses bound to the host):

exec python3 -m debugpy --listen 0.0.0.0:5678 --wait-for-client some_file.py

answered Dec 5, 2020 at 6:55

xdhmoore

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