os/modules/core/nix.nix

{
  config,
  pkgs,
  lib,
  inputs,
  ...
}: {
  nix = {
    # Use default version alias for nix package
    package = pkgs.nix;
    gc.automatic = true;
    optimise.automatic = true;
    settings = {
      # Improve nix store disk usage
      auto-optimise-store = true;
      # Prevents impurities in builds
      sandbox = true;
      # Give root and @wheel special privileges with nix
      trusted-users = ["root" "@wheel"];
      # Allow only group wheel to connect to the nix daemon
      allowed-users = ["@wheel"];
    };
    # Generally useful nix option defaults
    extraOptions = lib.mkForce ''
      min-free = 536870912
      keep-outputs = true
      keep-derivations = true
      fallback = true
    '';
  };
}