# /etc/nixos/configuration.nix 

{ config, pkgs, ... }:

{
  # ...

  # If you are using an SSD it may be useful to enable TRIM support as well as set filesystem flags to improve the SSD performance:
  fileSystems."/".options = [ "noatime" "nodiratime" "discard" ];

}

# /etc/nixos/configuration.nix 

{ config, pkgs, ... }:

{
  # ...

  # Zsh
  programs.zsh.enable = true;
  users.users.jakub.shell = pkgs.zsh;
}

# /etc/nixos/configuration.nix 

{ config, pkgs, ... }:

{
  # ...

  # Docker
  virtualisation.docker.enable = true;
  users.extraGroups.docker.members = [ "jakub" ];
}

# /etc/nixos/configuration.nix 

{ config, pkgs, ... }:

{
  # ...

  # Virtualbox
  virtualisation.virtualbox.host.enable = true;
  users.extraGroups.vboxusers.members = [ "jakub" ];
}

# /etc/nixos/configuration.nix 

{ config, pkgs, ... }:

{
  # ...

  # Enable CUPS to print documents.
  services.printing.enable = true;
  services.printing.drivers = [
    pkgs.gutenprint
    pkgs.gutenprintBin
    pkgs.canon-cups-ufr2
  ];

  # https://nixos.wiki/wiki/Printing
  services.avahi = {
    enable = true;
    nssmdns = true;
    openFirewall = true;
  };
}

# /etc/nixos/configuration.nix 

{ config, pkgs, ... }:

{
  # ...

  # Nix settings
  nix.settings = {
    # Enable flakes and new 'nix' command
    experimental-features = "nix-command flakes";
    # Deduplicate and optimize nix store
    auto-optimise-store = true;
    # Allowed users - needed for Home manager
    allowed-users = [ "@wheel" ];
  };
}

# ~/.config/home-manager/home.nix
{
  inputs,
  lib,
  config,
  pkgs,
  ...
}: {
  imports = [
    # ...
    ./systemd.nix
  ];
}

# ~/.config/home-manager/systemd.nix
{
  inputs,
  lib,
  config,
  pkgs,
  ...
}: {
  systemd.user.services.foo = {
    Unit = { Description = "Foo service"; };

    Service = {
      Type = "oneshot";
      WorkingDirectory = "/home/jakub/foo-app";
      ExecStart = "/home/jakub/Work/foo-app/foo run";
    };
  };

  systemd.user.timers.foo = {
    Unit = { Description = "Foo timer"; };

    Timer = {
      OnCalendar = "*-*-* *:00:00";
      Unit = "foo.service";
    };

    Install = { WantedBy = [ "timers.target" ]; };
  };
}