Nix for Python

Nix enables reproducible and isolated Python environments. Flakes are the modern way to manage Nix configurations. direnv auto-activates these environments per project.

1. Prerequisites

• Install Nix.
• Enable Nix flakes in nix.conf:

  experimental-features = nix-command flakes

• [Optional] direnv

2. flake.nix (Project Root)

{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
  };

  outputs = { self, nixpkgs, ... }:
  let
    pkgs = import nixpkgs { system = builtins.currentSystem; };
  in
  {
    devShell.default = pkgs.mkShell {
      packages = [
        pkgs.python3
        pkgs.python3Packages.pip
        # Add other Python packages
      ];
    };
  };
}

3. Enter Nix Shell

nix develop

TIP

You might have to git add the flake file first depending on your settings

4. direnv Integration

.envrc (Project Root)

dotenv # optional: load in environment variables from .env file
use flake # automatically enter dev shell
layout python # setup a python virtual env

Allow direnv

direnv allow

Now, Python and specified packages are auto-activated when you cd into the project directory.