Poetry2Nix Development Flake with Matplotlib GTK Support

I recently had the pleasure to dive back into python for work. In the past, I was happily using org-babel notebooks through emacs-jupyter. However, I have since switched to a more REPL/script driven workflow as I find that programming notebooks require a great deal of discipline to not end up as a horrible mess. For my new workflow, I need interactive plotting to work.

So let’s get straight to the meat. The following Flake dives you a development shell that tries to replicate the underlying poetry project in full nix using poetry2nix.

{
  description = "[your description]";

  inputs = {
    flake-utils.url = "github:numtide/flake-utils";
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable-small";
    poetry2nix = {
      url = "github:nix-community/poetry2nix";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  outputs = inputs @ { self, nixpkgs, flake-utils, ... }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = nixpkgs.legacyPackages.${system};
        poetry2nix = inputs.poetry2nix.lib.mkPoetry2Nix { inherit pkgs; };
      in
      {
        packages = {
          yourPackage = poetry2nix.mkPoetryApplication {
            projectDir = self;

            # set this to true to use premade wheels rather than the source
            preferWheels = false;

            # this enables interactive plotting support with GTK
            overrides = poetry2nix.overrides.withDefaults (final: prev: {
              matplotlib = with pkgs; prev.matplotlib.overridePythonAttrs 

                {
                  passthru.args.enableGtk3 = true;
                };
            });
          };
          default = self.packages.${system}.yourPackage;
        };

        # Shell for app dependencies.
        #
        # nix develop
        #
        # Use this shell for developing your app.
        devShells.default = pkgs.mkShell {
          inputsFrom = [self.packages.${system}.yourPackage];
          package = with pkgs; [
            # any development dependencies that you might have in nixpkgs
            ruff
            pyright
          ];
        };

        # Shell for poetry.
        #
        # nix develop .#poetry
        #
        # Use this shell for changes to pyproject.toml and poetry.lock.
        devShells.poetry = pkgs.mkShell {
          packages = [pkgs.poetry];
        };
      });
}

The workflow is as follows. Running nix develop .#poetry will give you a shell with poetry available. You can then poetry init and poetry addand poetry lock (not install) to your hearts content. A plain nix develop will then set up the environment according to the poetry.lockthat poetry generates. Note that this pull request has to be resolved before the above works with preferWheels = true.

You might want to checkout direnv and nix-direnv for added convenience.

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Poetry2Nix Development Flake with Matplotlib GTK Support

Valentin Boettcher

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