{ lib, config, pkgs, ... }: {
  imports = [

    <backup-module>
    <krops-lib>
    <cluster-module>
    <modules>

    # needed
    <home-manager/nixos>

    # cross-compiling
    #<cleverca22/qemu.nix>

    ./grub.nix
    ./networking-qos.nix
    ./nginx-landingpage.nix
    ./nginx.nix
    ./packages.nix
    ./restic.nix
    ./sftp-user.nix
    ./sshd-known-hosts-bootup.nix
    ./sshd-known-hosts-private.nix
    ./sshd-known-hosts-public.nix
    ./sshd.nix
    ./syncthing.nix
    ./tinc.nix

  ];

  # provide overlays
  # -----------------
  nixpkgs.overlays = [ (import <pkgs>) (import <nix-writers/pkgs>) ];

  # allow un-free
  # -------------
  nixpkgs.config.allowUnfree = true;
  environment.variables.NIXPKGS_ALLOW_UNFREE = "1";

  # some system stuff
  # -----------------
  #time.timeZone = lib.mkDefault "Europe/Berlin";
  #time.timeZone = lib.mkDefault "Pacific/Auckland";
  #time.timeZone = lib.mkDefault "Asia/Singapore";
  time.timeZone = lib.mkDefault "Asia/Makassar";

  i18n = {
    consoleFont = "Lat2-Terminus16";
    consoleKeyMap = "us";
    defaultLocale = "en_US.UTF-8";
  };

  # swappiness
  # ----------
  # 0 = only when running out of RAM
  # 100 = always swapp
  boot.kernel.sysctl."vm.swappiness" = 0;

  # rewire NIX_PATH
  # ---------------
  environment.variables.NIX_PATH = lib.mkForce "/var/src";

  # Shell configuration
  # -------------------
  programs.custom = {
    bash.enable = true;
    zsh.enable = true;
  };

  # This value determines the NixOS release with which your system is to be
  # compatible, in order to avoid breaking some software such as database
  # servers. You should change this only after NixOS release notes say you
  # should.
  system.stateVersion = "19.03"; # Did you read the comment?

}