fix-python

Work with Python "normally" on NixOS in one command!

Tired of all these "*.so not found" errors? Change the RPATH of all the binaries in your venv!

Requirements

• Nix
• nix-command and flakes experimental features must be enabled

Install

Use temporarily in a shell

nix shell github:GuillaumeDesforges/fix-python

Or add it to your profile

nix profile install github:GuillaumeDesforges/fix-python

Usage

In your Python project, create a virtual environment .venv and use your preferred tool (pip, poetry, ...) to install your dependencies.

[!IMPORTANT] fix-python will patch binary files in the virtual environment without following symlinks.

For example, if you use the venv module from Python's standard library, please make sure you pass --copies when creating the environment.

python -m venv .venv --copies

By default, fix-python patches the packages given in the following expression:

let pkgs = import (builtins.getFlake "nixpkgs") { };
in [
  pkgs.gcc.cc
  pkgs.glibc
  pkgs.zlib
]

Note: these three packages are fundamental for most Python packages and should never be removed.

If you need to patch packages in addition to these, create a .nix/libs.nix file with a structure similar to the above that returns the array of packages that you want binaries to be linked with.

Note: you may add this .nix folder to your project .gitignore.

Finally, call fix-python.

fix-python --venv .venv [--libs .nix/libs.nix]

The list of options is:

$ ./fix-python --help
Usage: fix-python --venv .venv [--libs libs.nix] [--no-default-libs]
--help: show this help message
--venv: path to Python virtual environment
--libs: path to a Nix file which returns a list of derivations
--no-default-libs: don't patch C++ standard libraries, glibc, and zlib by default
--gpu: enable GPU support
--with-torch: fix pytorch dependencies issues
--deep: looks for anything executable to patch, very slow but needed sometimes (e.g. PyQt)
--verbose: increase verbosity