flake/nixos/modules/networking/dns.nix

{
  lib,
  config,
  ...
}: let
  cfg = config.myFlake.nixos.networking.dns;
in {
  options = {
    myFlake.nixos.networking.dns = {
      provider = lib.mkOption {
        type = lib.types.enum ["google" "alidns"];
        default = "google";
        example = "alidns";
        description = "Select desired DNS provider.";
      };
    };
  };

  config = {
    networking.nameservers = lib.mkMerge [
      (lib.mkIf (cfg.provider == "google") [
        ### Google DNS
        "8.8.8.8"
        "8.8.4.4"
        "2001:4860:4860::8888"
        "2001:4860:4860::8844"
      ])
      (lib.mkIf (cfg.provider == "alidns") [
        ### AliDNS
        "223.5.5.5"
        "223.6.6.6"
        "2400:3200::1"
        "2400:3200:baba::1"
      ])
    ];
  };
}