{
  description = "A very basic flake";
  nixConfig = {
    extra-substituters = [
      "https://nix-community.cachix.org"
    ];
    extra-trusted-public-keys = [
      "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
    ];
  };

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
    authentik = {
      url = "github:nix-community/authentik-nix";
    };
    mailserver.url = "gitlab:simple-nixos-mailserver/nixos-mailserver";
  };

  outputs = { self, nixpkgs, authentik, mailserver }: {
    formatter.x86_64-linux = nixpkgs.legacyPackages.x86_64-linux.nixpkgs-fmt;

    nixosConfigurations = {
      authentik = nixpkgs.lib.nixosSystem {
        system = "x86_64-linux";
        modules = [
          ./configuration.nix
          authentik.nixosModules.default
          mailserver.nixosModules.mailserver
        ];
      };
    };
  };
}