Using Qtile changes Python environment

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1

Hello everyone,

I have a problem similar to the one discussed on this reddit forum, which deals with some clash of Python environments when installing Qtile on NixOS. To elaborate, I have this on my configuration.nix:

services.xserver.windowManager = {
  qtile = {
    enable = true;
  };
};
...
environment.systemPackages = with pkgs; [
...
 (let
  my-python-packages = python-packages: with python-packages; [
    matplotlib
    numpy
    pandas
    scikit-learn
  ];
  python-with-my-packages = python3.withPackages my-python-packages;
  in
    python-with-my-packages)
...
];

If I disable Qtile I am able to work with my globally defined Python environment:

$ python -c "import numpy"
$ python -c "import sys; print(sys.prefix)"
/nix/store/kc9bsiwsbadhs165ryr4b6xbsb0wccmc-python3-3.9.6-env

However, when I enable Qtile the Python environment changes, and the packages I added globally are not available anymore:

$ python -c "import numpy"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
ModuleNotFoundError: No module named 'numpy'
$ python -c "import sys; print(sys.prefix)"
/nix/store/z43s37a755b2i8nd6mibjzjjjjdl7f3n-qtile-0.18.1

How could I use Qtile and at the same time keep my global environment?

2

eh, probably this is due to how qtile is packaged, as it uses .withPackages as well. This is the relevant lines from its package definition:

(python3.withPackages (_: [ unwrapped ])).overrideAttrs (_: {
  # otherwise will be exported as "env", this restores `nix search` behavior
  name = "${unwrapped.pname}-${unwrapped.version}";
  # export underlying qtile package
  passthru = { inherit unwrapped; };

  # restore original qtile attrs
  inherit (unwrapped) pname version meta;
})

… this final package is then added to systemPackages when you enable qtile. So both packages (yours and qtile’s) add a python executable to the PATH and it seems that qtile’s is the one that comes first in the PATH and gets invoked.

Now, I don’t know why qtile packager did this because I don’t use it, the best thing to do is to open an issue or a pull request on nixpkgs

1 Like
3

Thank you very much for your reply. The issue has been solved by #167381.