os/modules/core/nix.nix

{
  config,
  pkgs,
  lib,
  inputs,
  ...
}: {
  nix = {
    # Use default version alias for nix package
    package = pkgs.nix;
    # Improve nix store disk usage
    autoOptimiseStore = true;
    gc.automatic = true;
    optimise.automatic = true;
    # Prevents impurities in builds
    useSandbox = true;
    # give root and @wheel special privileges with nix
    trustedUsers = ["root" "@wheel"];
    # This is just a representation of the nix default
    systemFeatures = ["nixos-test" "benchmark" "big-parallel" "kvm"];
    # Generally useful nix option defaults
    extraOptions = ''
      min-free = 536870912
      keep-outputs = true
      keep-derivations = true
      fallback = true
    '';
  };
}