{ config, pkgs, ... }:
{
  imports = [
    # Shell settings
    #.
    ./bash.nix # bash settings.
    ./zsh.nix # zsh as default shell for yoda and root.
    ./fzf.nix # Fuzzy command history and file search.

    # DNS settings.
    #
    # TODO add nix option
    ./dns.nix # Encrypted DNS queries to custom name servers.
    #./dns-unencrypted.nix # Custom name servers.

    # Nix garbage collection.
    ./nix-gc.nix
    # Display contact information during boot.
    ./initrd-contact-info.nix
  ];

  # Firmware.
  #
  # The list of hardware.enableAllFirmware contains non-redistributable licensed firmware files.
  # This requires nixpkgs.config.allowUnfree to be true.
  # An alternative is to use the hardware.enableRedistributableFirmware option.
  hardware.enableAllFirmware = false;
  #
  # Enables e.g. Intel microcode updates.
  # Defaults to `config.hardware.enableAllFirmware`.
  hardware.enableRedistributableFirmware = true;

  # Allow **all** unfree packages.
  # To whitelist individual unfree packages, see ./unfree.nix
  nixpkgs.config.allowUnfree = false;

  # Enables wireless support via wpa_supplicant.
  # networking.wireless.enable = true;

  # Enable networking.
  networking.networkmanager.enable = true;

  # Set your time zone.
  time.timeZone = "Europe/Berlin";

  # Select internationalisation properties.
  i18n.defaultLocale = "en_US.UTF-8";
  i18n.extraLocaleSettings = {
    LC_ADDRESS = "de_DE.UTF-8";
    LC_IDENTIFICATION = "de_DE.UTF-8";
    LC_MEASUREMENT = "de_DE.UTF-8";
    LC_MONETARY = "de_DE.UTF-8";
    LC_NAME = "de_DE.UTF-8";
    LC_NUMERIC = "de_DE.UTF-8";
    LC_PAPER = "de_DE.UTF-8";
    LC_TELEPHONE = "de_DE.UTF-8";
    LC_TIME = "de_DE.UTF-8";
  };

  console = {
    #font = "Lat2-Terminus16";
    # Configure console keymap.
    keyMap = "de-latin1-nodeadkeys";
  };

  # Define a user account.
  # Don't forget to set a password with `passwd`.
  users.users.yoda = {
    isNormalUser = true;
    description = "Yoda";
    extraGroups = [ "networkmanager" "wheel" ];
    packages = with pkgs; [
    ];
  };

  # SystemMaxFileSize: Defaults to one eighth of the values configured with SystemMaxUse= and RuntimeMaxUse=, so that usually seven rotated journal files are kept as history.
  # MaxFileSec: To ensure that not too much data is lost at once when old journal files are deleted, it might make sense to change this value from the default of one month.
  # https://www.freedesktop.org/software/systemd/man/journald.conf.html
  services.journald.extraConfig = ''
    SystemMaxUse=800M
    MaxFileSec=7day
  '';

  nix.settings.auto-optimise-store = true;

  # Delete all files in /tmp during boot.
  boot.tmp.cleanOnBoot = true;

  # Whether to install NixOS's own documentation.
  documentation.nixos.enable = false;

  # Firewall.
  # https://nixos.wiki/wiki/Firewall
  # Note: Firewall rules may be bypassed/overwritten by Docker, as per https://github.com/NixOS/nixpkgs/issues/111852
  networking.firewall.enable = true;

  # Options only for build.system.vm - they won’t get applied when building build.system.toplevel aka the normal system config.
  # https://discourse.nixos.org/t/wayland-compositors-an-build-vm-not-working/46486/2
  virtualisation.vmVariant = {
    users.users.yoda.initialPassword = "asdf";
    virtualisation.qemu.options = [
      "-device virtio-vga-gl"
      "-display sdl,gl=on,show-cursor=off"
      "-m 8G"
    ];
  };
}