Debugging a PDM-managed project in VSCode

[pawamoy]

I had a bit of trouble setting up VSCode to be able to debug my code and add breakpoints onto the libraries installed in __pypackages__, so here is a how to.

First, know that I installed PDM with pipx:

pipx install pdm

It used my system Python, which is /usr/bin/python, and is version 3.9.
If I wanted to use another version, I would have installed it like this:

pipx install --python python3.8 pdm

Then I set up my project to use Python 3.9 and installed the libraries:

cd myproject
pdm use -f 3.9
pdm install -d

My code lives in the src folder.

In VSCode, I defined the Python interpreter to /usr/bin/python.
I then added a Run configuration which sets the PYTHONPATH environment variable so Python can find both my code and the libraries in __pypackages__.

.vscode/settings.json

{
    "python.pythonPath": "/usr/bin/python"
}

.vscode/launch.json

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "pytest",
            "type": "python",
            "request": "launch",
            "module": "pytest",
            "args": ["-c", "config/pytest.ini", "-n", "auto", "tests"],
            "justMyCode": false,
            "env": {"PYTHONPATH": "src:__pypackages__/3.9/lib"}
        }
    ]
}

If you set up a different Python interpreter, make sure you set the env accordingly. For example with a Python 3.8 interpreter, add __pypackages__/3.8/lib to the Python path.

[sleiner]

Thanks for the showcase! :-) After setting up VS Code for PDM as described in the current docs, I did not have to use any additional setup to get debugging and even running tests from the sidebar working. So no need for specialized launch configurations :-)

[pawamoy]

You're right, my hack above should not be needed anymore 🎉
Thanks for the feedback!

[Hnasar]

I see your tip of using env is mentioned in the docs under the Cannot enable PEP582 globally? heading.

What I ended up doing was, to set this globally, rather than in each project's launch.json, I added this to settings.json:

    "python.envFile": "${userHome}/.vscode/pyenv",

and in that pyenv file:

PYTHONPATH=c:\users\<my username here>\appdata\roaming\pdm\venv\lib\site-packages\pdm\pep582

(which is the PYTHONPATH set by pdm --pep582 in System Properties -> Advanced -> Environment Variables (using Windows))

But indeed, once I enabled PEP-582 globally then this option wasn't needed either! 🎉