{
  lib,
  pkgs,
  ...
}:
{
  nix = {
    package = lib.mkDefault pkgs.nix;

    settings = {
      # it is impossible to anser in nix-direnv, so we force it to off.
      # https://github.com/nix-community/nix-direnv/issues/678
      accept-flake-config = lib.mkForce false;

      # Try to have at least 10GB of space by default
      min-free = lib.mkDefault (5 * 1024 * 1024 * 1024);
      max-free = lib.mkDefault (10 * 1024 * 1024 * 1024);

      extra-substituters = [
        "https://nix-community.cachix.org"
      ];
      extra-trusted-substituters = [
        "https://nix-community.cachix.org"
      ];
      extra-trusted-public-keys = [
        "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
      ];
    };
  };
}