Template: Default

The default template is the recommended way to start a new Den project. It includes flake-parts, Home-Manager, dendritic flake-file, and a VM for testing.

Initialize

mkdir my-nix && cd my-nix
nix flake init -t github:vic/den#default
nix flake update den

Project Structure

flake.nix              # auto-generated by flake-file
modules/
  dendritic.nix        # flake-file + den dendritic setup
  hosts.nix            # host and user declarations
  defaults.nix         # global settings (stateVersion, etc.)
  igloo.nix            # host aspect
  tux.nix              # user aspect
  vm.nix               # VM runner

File by File

hosts.nix — Declare Your Infrastructure

{
  den.hosts.x86_64-linux.igloo.users.tux = { };
}

This single line declares:

• A host igloo on x86_64-linux (class: nixos)
• A user tux on that host (class: homeManager)

The host and user each get an aspect (den.aspects.igloo and den.aspects.tux) that you configure in separate files.

igloo.nix — Host Aspect

{
  den.aspects.igloo = {
    nixos = { pkgs, ... }: {
      environment.systemPackages = [ pkgs.hello ];
    };
    homeManager = { pkgs, ... }: {
      home.packages = [ pkgs.vim ];
    };
  };
}

The host aspect provides:

• NixOS config — system packages available to all users
• Home-Manager config — default home environment for every user on this host

tux.nix — User Aspect

{ den, ... }:
{
  den.aspects.tux = {
    includes = [
      den.provides.primary-user
      (den.provides.user-shell "fish")
    ];
    homeManager = { pkgs, ... }: {
      home.packages = [ pkgs.htop ];
    };
  };
}

The user aspect:

• Includes primary-user — adds wheel + networkmanager groups
• Includes user-shell — sets fish as default shell at OS and HM level
• Provides personal Home-Manager packages

defaults.nix — Global Settings

{
  den.default.nixos.system.stateVersion = "25.11";
  den.default.homeManager.home.stateVersion = "25.11";
}

den.default applies settings to all hosts, users, and homes. This is the right place for stateVersion and other global policies.

vm.nix — Test in a VM

{ inputs, den, ... }:
{
  den.aspects.igloo.includes = [ (den.provides.tty-autologin "tux") ];

  perSystem = { pkgs, ... }: {
    packages.vm = pkgs.writeShellApplication {
      name = "vm";
      text = let
        host = inputs.self.nixosConfigurations.igloo.config;
      in ''
        ${host.system.build.vm}/bin/run-${host.networking.hostName}-vm "$@"
      '';
    };
  };
}

Run the VM with:

nix run .#vm

dendritic.nix — Flake Wiring

{ inputs, ... }:
{
  imports = [
    (inputs.flake-file.flakeModules.dendritic or { })
    (inputs.den.flakeModules.dendritic or { })
  ];
  flake-file.inputs = {
    den.url = "github:vic/den";
    flake-file.url = "github:vic/flake-file";
    home-manager = {
      url = "github:nix-community/home-manager";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };
}

This uses flake-file so inputs can be defined close to where they are used. Run nix run .#write-flake to regenerate flake.nix after changing inputs.

Data Flow

graph TD
  H["hosts.nix: igloo + tux"] --> CH["ctx.host {host=igloo}"]
  CH --> AI["den.aspects.igloo<br/>nixos + homeManager"]
  CH --> CU["ctx.user {host=igloo, user=tux}"]
  CU --> AT["den.aspects.tux<br/>primary-user + fish + htop"]
  CH --> HM["ctx.hm-host: import HM module"]
  HM --> HMU["ctx.hm-user: forward homeManager<br/>into home-manager.users.tux"]
  AI --> NixOS["nixosConfigurations.igloo"]
  AT --> NixOS
  HMU --> NixOS

What It Provides

Feature	Provided
NixOS host configuration	✓
Home-Manager integration	✓
Dendritic flake-file	✓
VM testing	✓
flake-parts	✓
Darwin support	Add input
Namespaces	Add manually

Next Steps

• Edit hosts.nix to add more hosts or users
• Create new aspect files under modules/
• Add Darwin support by adding nix-darwin input
• Explore the Example template for namespaces and advanced features