los

los provides Nix flake, modules, and library for NixOS systems.

The L in los was picked randomly, and could stand for last, light, or even loser.

Structure

Modules

Modules are organized under ./modules:

• modules/system/ — System-wide NixOS modules
• modules/home/ — Per-user modules (with username: closure)

There's only 1 rule for modules: a system module must never touch user modules.

We allow user modules to read or even set values of system modules, or even nixosConfigurations itself, if that's the natural way to implement the module.

• System modules in modules/system/

  The root of this module is the top-level los

  The modules here provide los system options like networking, mountpoints, users, and doas.

• User modules in modules/home/

  The modules here provide los.home user options like program configurations, user-specific packages, etc.

  Directory structure

  • dm/ — Display manager related configs (sway, pipewire, fonts)
  • languages/ — Programming language support
  • firefox/ — Firefox browser configuration
  • git/ — Git version control configuration
  • helix/ — Helix editor configuration
  • lf/ — lf file manager configuration
  • vscodium/ — VSCodium editor configuration

  And it goes on.

  User-specific options

  Options under los.home are user-specific. The per-user configuration is implemented by simple, stupid functional module factories that takes in a username and returns a user-specific los modules under los.home.${username}.

  The options los.home.${username} will then be mapped to home-manager.users.${username}.

  Note that home-manager.sharedModules is not used because some modules here might need to set system configurations too, usually low-level or security-related NixOS options.

  DM abstraction

  The dm/ module provides shared display manager settings:

  • los.home.${username}.dm.pipewire.enable — Audio/screen sharing support
  • los.home.${username}.dm.fonts — Font configuration
  • los.home.${username}.dm.sway — Sway window manager

  Other modules (like Firefox) can reference dm.pipewire.enable to determine whether to enable Pipewire support, avoiding configuration races.

• Standalone Home Manager entry

  The home/default.nix file is the flake entry point for standalone homeConfigurations, used for non-NixOS systems (e.g., macOS).

Host configurations

Per-host configurations should be consolidated into a single module under ./hosts.

Preferrably, these hosts modules should not declare any options (i.e. they are imports-only modules), and they should not touch user modules directly.

This is because hosts are bare-minimum builds that can boot and connect to the internet.

The way I like it is to use host configuration as the base, and build up from there with modules and presets.

Misc.

• Library (very opinionated)

  Simple (sometimes useless) non-module Nix code, usually functions.

• Package lists

  List of package names to be imported by syspkgs module.

  Each text line is treated as pname of a Nix package.

• Default settings

  Ready-to-go, import-only modules with no options defined.

• Presets and profiles

  Like defaults, but more complex. An example is sway-dev, which provides my working environment using Sway and Helix.

  Presets usually cover everything but the boot process or hardware settings.

  Lower-level, machine-specific configuration like the boot process, mountpoints, and kernel settings should be defined in hosts/<host>/default.nix.

  Like with defaults, they provide no options.