Host Template System¶

The problem¶

Three hosts, each historically carrying its own near-identical import list and boilerplate. Adding a module meant editing every host; the lists drifted.

The solution¶

A single parameterised template at hosts/templates/desktop.nix, surfaced through lib/hostTypes.nix as two entry points:

hostTypes.workstation — used by p620 and p510
hostTypes.laptop — used by razer

The template takes one argument, profile, and imports the entire module tree. Profile-specific behaviour is applied with lib.mkIf.

{ profile ? "workstation" }:
{ lib, ... }:
{
  imports = [
    ../../modules/core.nix
    ../../modules/development.nix
    ../../modules/desktop.nix
    ../../modules/virtualization.nix
    ../../modules/performance.nix
    ../../modules/email.nix
    ../../modules/cloud.nix
    ../../modules/programs.nix
    ../../modules/common/ai-defaults.nix
    ../../modules/windows/winboat.nix
  ];

  config = lib.mkMerge [
    {
      aiDefaults.enable = lib.mkDefault true;
      services.openssh.enable = lib.mkDefault true;
    }
    (lib.mkIf (profile == "laptop") {
      services.thermald.enable = lib.mkDefault true;
      powerManagement = {
        enable = lib.mkDefault true;
        cpuFreqGovernor = lib.mkDefault "powersave";
      };
    })
  ];
}

How a host wires in¶

lib/hostTypes.nix wraps the template and layers on sensible feature defaults that a host can still override with mkForce:

workstation = {
  imports = [ (desktopTemplate "workstation") ];
  config = {
    aiDefaults.profile = "workstation";
    features = {
      development.enable = lib.mkDefault true;
      desktop.enable = lib.mkDefault true;
      virtualization.enable = lib.mkDefault true;
    };
  };
};

A host's configuration.nix then imports the host type and declares only what is unique to it.

Why mkDefault everywhere

The template sets defaults, not hard values. A host that needs something different (e.g. p510 running headless with no display manager) overrides cleanly without fighting the template.

Headless from the same template¶

p510 is a server, yet it uses the workstation template. Rather than maintain a separate server template (the old server/hybrid/base templates were removed), p510 simply:

sets host.class = "workstation",
disables the display manager and desktop compositor,
enables GNOME Remote Desktop for the rare time a GUI is needed.

This keeps one template instead of three and avoids the divergence that the template system exists to prevent.

Adding a new host¶

Create hosts/<name>/ with variables.nix and hardware-configuration.nix.
Import the appropriate host type (hostTypes.workstation or hostTypes.laptop).
Declare host-unique bits (GPU profile, monitors, host-specific features).
Register it in flake.nix (hostUsers, hardwareProfiles).
Add the host SSH key to secrets/secrets.nix and rekey.

Full procedure: Adding a Host.