python flake

flake.nix

{
  description = "Python dev shell";
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    flake-utils.url = "github:numtide/flake-utils";
    mach-nix.url = "github:davhau/mach-nix";
  };
  outputs = { self, nixpkgs, flake-utils, mach-nix, ... }:
    flake-utils.lib.eachDefaultSystem
      (system:
        let
          pkgs = import nixpkgs {
            inherit system;
          };
          pythonVersion = "python39";
          mach = mach-nix.lib.${system};
          requirements = builtins.readFile ./requirements.txt;
          pythonEnv = mach.mkPython {
            python = pythonVersion;
            inherit requirements;
          };
          dockerImage = mach.mkDockerImage {
            inherit requirements;
          };
        in
        with pkgs;
        {
          packages = {
            image = dockerImage.override {
              name = "pythonapp";
              tag = "latest";
              contents = [
                ([ pythonEnv ] ++ [ pkgs.bash ])
              ];
            };
          };
          devShells.default = mkShell {
            buildInputs = [
              dive
              google-cloud-sdk
              pythonEnv
            ];
          };
        }
      );
}