nixos-flake/flake.nix

{
  inputs = {
    #nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.05";
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.11";
    stable.url = "github:NixOS/nixpkgs/nixos-23.11";
    unstable.url = "github:NixOS/nixpkgs/nixos-unstable";
  };
  outputs = { self, nixpkgs, stable, unstable }@attrs: {
    nixosConfigurations.harrowhark = nixpkgs.lib.nixosSystem rec {
      pkgs = let
        nixpkgsConfig = {
          inherit system;
          config.allowUnfree = true;
        };
      in import nixpkgs (nixpkgsConfig // {
        overlays = [
          (new: prev: {
            unstable = import unstable nixpkgsConfig;
            stable = import stable nixpkgsConfig;
          })
        ];
      });
      system = "x86_64-linux";
      modules = [
        ./configuration.nix
        # This fixes nixpkgs (for e.g. "nix shell") to match the system nixpkgs
        ({ config, pkgs, options, ... }: {
          nix.registry.nixpkgs.flake = nixpkgs;
        })
      ];
    };
  };
}