My first ever NixOS configuration, written back at the start of 2019.

pelmeshka-computer2-configuration.nix

# Edit this configuration file to define what should be installed on
# your system.  Help is available in the configuration.nix(5) man page
# and in the NixOS manual (accessible by running ‘nixos-help’).

{ config, pkgs, lib, ... }:

{
  imports = [
    # Include the results of the hardware scan.
    ./hardware-configuration.nix
  ];

  # Use the systemd-boot EFI boot loader.
  boot = {
    loader = {
      systemd-boot.enable = true;
      efi.canTouchEfiVariables = true;
    };
    earlyVconsoleSetup = true;
    postBootCommands = ''
      ${pkgs.kbd}/bin/setvtrgb - <<EOF
      45,242,153,255,102,204,102,211,116,242,153,255,102,204,102,242
      45,119,204,204,153,153,204,208,115,119,204,204,153,153,204,240
      45,122,153,102,204,204,204,200,105,122,153,102,204,204,204,236
      EOF
    '';
  };

  hardware.cpu.intel.updateMicrocode = true;

  fileSystems."/mnt/Arch" = {
    device = "/dev/disk/by-partlabel/Arch";
    fsType = "ext4";
  };


  networking.hostName = "pelmeshka-computer2-nixos";
  networking.networkmanager.enable = true;
  services.avahi = {
    enable = true;
    nssmdns = true;
    publish = {
      enable = true;
      addresses = true;
    };
  };

  # The global useDHCP flag is deprecated, therefore explicitly set to false here.
  # Per-interface useDHCP will be mandatory in the future, so this generated config
  # replicates the default behaviour.
  networking.useDHCP = false;
  networking.interfaces.enp8s0.useDHCP = true;
  networking.interfaces.wlp9s0.useDHCP = true;

  i18n = {
    consoleFont = "Lat2-Terminus16";
    consoleKeyMap = "us";

    defaultLocale = "en_US.UTF-8";
    extraLocaleSettings = {
      LC_COLLATE = "C";
      LC_TIME = "en_GB.UTF-8";
      LC_MESSAGES = "en_US.UTF-8";

      LC_IDENTIFICATION = "uk_UA.UTF-8";
      LC_ADDRESS = "uk_UA.UTF-8";
      LC_MONETARY = "uk_UA.UTF-8";
      LC_MEASUREMENT = "uk_UA.UTF-8";
      LC_NAME = "ru_RU.UTF-8";
      LC_NUMERIC = "uk_UA.UTF-8";
      LC_PAPER = "uk_UA.UTF-8";
      LC_TELEPHONE = "uk_UA.UTF-8";
    };
  };

  security.sudo.extraConfig = ''
    # Show asterisks when typing passwords.
    Defaults pwfeedback

    # Disable launching arbitrary editors from the EDITOR, VISUAL and SUDO_EDITOR
    # variables when using visudo because this is a potential security hole.
    Defaults !env_editor
    # Whitelist of editors which visudo is allowed to run.
    Defaults editor=${pkgs.neovim}/bin/nvim:${pkgs.vim}/bin/vim:${pkgs.nano}/bin/nano
    # Pass-through the editor environment variables so that visudo will be able to
    # see them.
    Defaults env_keep+="EDITOR VISUAL SUDO_EDITOR"
  '';

  time.timeZone = "Europe/Kiev";

  # List packages installed in system profile. To search, run:
  # $ nix search wget
  environment.systemPackages = with pkgs; [
    python
    (python3.withPackages (pypkgs: with pypkgs; [
      psutil
      distro
      colorama
    ]))

    # editor
    vim
    neovim

    # desktop
    xdg-user-dirs

    # utilities
    wget
    htop
    cmatrix
    zsh
    git
    file
  ];

  # Some programs need SUID wrappers, can be configured further or are
  # started in user sessions.
  # programs.mtr.enable = true;
  # programs.gnupg.agent = { enable = true; enableSSHSupport = true; };

  # List services that you want to enable:

  services.openssh = {
    enable = true;
    passwordAuthentication = false;
  };

  # Open ports in the firewall.
  # networking.firewall.allowedTCPPorts = [ ... ];
  # networking.firewall.allowedUDPPorts = [ ... ];
  # Or disable the firewall altogether.
  networking.firewall.enable = false;

  # Enable CUPS to print documents.
  # services.printing.enable = true;

  # Enable sound.
  sound.enable = true;
  hardware.pulseaudio.enable = true;

  services.xserver = {
    enable = true;
    xkbModel = "pc104";
    layout = "us,ru,ua";
    xkbOptions = "grp:rctrl_rshift_toggle";
    xkbVariant = ",,winkeys";

    libinput = {
      enable = true;
    };

    displayManager.lightdm = {
      enable = true;
      greeters.gtk = {
        theme.name = "Adwaita-dark";
        # iconTheme.name = "MAZE-Faeza";
        iconTheme.name = "Adwaita";
        cursorTheme.name = "Adwaita";
        cursorTheme.size = 16;
        clock-format = "%a %b %d, %H:%M:%S";
        indicators = [ "~host" "~spacer" "~clock" "~spacer" "~language" "~session" "~a11y" "~power" ];
        extraConfig = ''
          laptop = true
          font-name = sans-serif 14
          screensaver-timeout = 60
        '';
      };
    };

    desktopManager = {
      xfce.enable = true;
      xterm.enable = false;
      default = "xfce";
    };
  };

  programs.zsh = {
    enable = true;
    # shellAliases = builtins.trace config.environment.shellAliases { l = null; ll = null; ls = null; };
    shellAliases = lib.mkForce {};
    promptInit = "";
    setOptions = [];
    enableCompletion = false;
  };

  # Define a user account. Don't forget to set a password with ‘passwd’.
  users.users.dmitmel = {
    isNormalUser = true;
    extraGroups = [
      "wheel" # Enable ‘sudo’ for the user.
      "networkmanager"
    ];
    shell = pkgs.zsh;
  };

  # 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 = "19.09"; # Did you read the comment?

}

pelmeshka-computer2-hardware-configuration.nix

# Do not modify this file!  It was generated by ‘nixos-generate-config’
# and may be overwritten by future invocations.  Please make changes
# to /etc/nixos/configuration.nix instead.
{ config, lib, pkgs, ... }:

{
  imports =
    [ <nixpkgs/nixos/modules/installer/scan/not-detected.nix>
    ];

  boot.initrd.availableKernelModules = [ "xhci_pci" "ehci_pci" "ahci" "usb_storage" "sd_mod" "sr_mod" ];
  boot.initrd.kernelModules = [ ];
  boot.kernelModules = [ "kvm-intel" ];
  boot.extraModulePackages = [ ];

  fileSystems."/" =
    { device = "/dev/disk/by-uuid/497317b3-90a3-46a5-b943-5adbc526c226";
      fsType = "ext4";
    };

  fileSystems."/boot" =
    { device = "/dev/disk/by-uuid/BF8C-CDAF";
      fsType = "vfat";
    };

  swapDevices =
    [ { device = "/dev/disk/by-uuid/54b918ae-732f-42dd-8c97-3f702d84e687"; }
    ];

  nix.maxJobs = lib.mkDefault 8;
  powerManagement.cpuFreqGovernor = lib.mkDefault "powersave";
}