nix/nixos/common/modules/nixos.nix

{ ... }: { 
  # Enable flakes:  https://nixos.wiki/wiki/Flakes
  nix.settings.experimental-features = [ "nix-command" "flakes" ];

  # Keep the system up-to-date automatically
  system = {
    autoUpgrade = {
      enable = true;
      allowReboot = false;
      dates = "daily";
      flake = "git+file:/etc/nixos/flake.nix";
    };
  };

  # Garbage collection -- Keep the system clean
  nix.gc = {
    automatic = true;
    dates = "daily";
    options = "--delete-older-than 7d";
  };
}