Configuration Initialization

This section will describe creating the minimal template from scratch.

You do not have to do this; you can simply clone the minimal configuration template with the following command:

nix flake init -t github:yunfachi/denix#minimal

You can also clone the minimal configuration template without the rices:

nix flake init -t github:yunfachi/denix#minimal-no-rices

Flake

First, create a directory for your configuration and a flake.nix file with the following content:

{
  description = "Modular configuration of NixOS, Home Manager, and Nix-Darwin with Denix";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
    home-manager = {
      url = "github:nix-community/home-manager/master";
      inputs.nixpkgs.follows = "nixpkgs";
    };
    denix = {
      url = "github:yunfachi/denix";
      inputs.nixpkgs.follows = "nixpkgs";
      inputs.home-manager.follows = "home-manager";
    };
  };

  outputs = {
    denix,
    nixpkgs,
    ...
  } @ inputs: let
    mkConfigurations = moduleSystem:
      denix.lib.configurations {
        inherit moduleSystem;
        homeManagerUser = "sjohn"; #!!! REPLACEME

        paths = [./hosts ./modules ./rices];

        specialArgs = {
          inherit inputs;
        };
      };
  in {
    # If you're not using NixOS, Home Manager, or Nix-Darwin,
    # you can safely remove the corresponding lines below.
    nixosConfigurations = mkConfigurations "nixos";
    homeConfigurations = mkConfigurations "home";
    darwinConfigurations = mkConfigurations "darwin";
  };
}

If you are not familiar with inputs and outputs, read NixOS Wiki Flakes.

Code explanation:

• mkConfigurations - a function to reduce code repetition, which takes moduleSystem and passes it to denix.lib.configurations.
• denix.lib.configurations - Configurations (flakes) - Introduction.
• paths = [./hosts ./modules ./rices]; - paths that will be recursively imported by Denix as modules. Remove ./rices if you don't plan to use rices.

Hosts

Create a hosts directory, and within it, create a subdirectory with the name of your host, for example, desktop.

In this subdirectory, create a default.nix file with the following content:

{delib, ...}:
delib.host {
  name = "desktop"; #!!! REPLACEME
}

In the same directory, create a hardware.nix file:

{delib, ...}:
delib.host {
  name = "desktop"; #!!! REPLACEME

  homeManagerSystem = "x86_64-linux"; #!!! REPLACEME
  home.home.stateVersion = "24.05"; #!!! REPLACEME

  # If you're not using NixOS, you can remove this entire block.
  nixos = {
    nixpkgs.hostPlatform = "x86_64-linux"; #!!! REPLACEME
    system.stateVersion = "24.05"; #!!! REPLACEME

    # nixos-generate-config --show-hardware-config
    # other generated code here...
  };

  # If you're not using Nix-Darwin, you can remove this entire block.
  darwin = {
    nixpkgs.hostPlatform = "aarch64-darwin"; #!!! REPLACEME
    system.stateVersion = 6; #!!! REPLACEME
  };
}

The default.nix file will be modified later after adding modules and rices, so you can keep it open.

Rices

Skip this section if you do not wish to use rices.

Create a rices directory, and within it, create a subdirectory with the name of your rice, for example, dark.

In this subdirectory, create a default.nix file with the following content:

{delib, ...}:
delib.rice {
  name = "dark"; #!!! REPLACEME
}

Modules

Create a modules directory, and within it, create a config subdirectory (typically, it contains modules that are not tied to a specific program or service).

It should be mentioned that modules represent your configuration, meaning it's up to your imagination, and you are free to change the modules as you wish.

Constants

In this subdirectory, create a constants.nix file with the following content:

{delib, ...}:
delib.module {
  name = "constants";

  options.constants = with delib; {
    username = readOnly (strOption "sjohn"); #!!! REPLACEME
    userfullname = readOnly (strOption "John Smith"); #!!! REPLACEME
    useremail = readOnly (strOption "johnsmith@example.com"); #!!! REPLACEME
  };
}

This file is optional, as are any of its options, which are only used by you, but it is recommended as good practice.

Hosts

Also, create a hosts.nix file in this same directory (modules/config), and write any example from Hosts - Examples.

For example, we will take "With the type Option":

{delib, ...}:
delib.module {
  name = "hosts";

  options = with delib; let
    host = {config, ...}: {
      options =
        hostSubmoduleOptions
        // {
          type = noDefault (enumOption ["desktop" "server"] null);

          isDesktop = boolOption (config.type == "desktop");
          isServer = boolOption (config.type == "server");
        };
    };
  in {
    host = hostOption host;
    hosts = hostsOption host;
  };

  home.always = {myconfig, ...}: {
    assertions = delib.hostNamesAssertions myconfig.hosts;
  };
}

If you added an example with new options (type, displays, etc.) or made your own options, don't forget to add values for these options in the hosts.

In our example, we added the type option, so open the default.nix file in your host's directory and add the attribute type to the delib.host function:

{delib, ...}:
delib.host {
  name = "desktop"; #!!! REPLACEME

  type = "desktop" #!!! REPLACEME ["desktop"|"server"]

  # ...
}

Rices

Skip this section if you are not using rices.

In the modules/config directory, create a rices.nix file, and write any example from Rices - Examples.

For example, we will take "Minimally Recommended Rice Module":

delib.module {
  name = "rices";

  options = with delib; let
    rice = {
      options = riceSubmoduleOptions;
    };
  in {
    rice = riceOption rice;
    rices = ricesOption rice;
  };

  home.always = {myconfig, ...}: {
    assertions = delib.riceNamesAssertions myconfig.rices;
  };
}

Also, open the default.nix file of your host and add the attribute rice to the delib.host function:

{delib, ...}:
delib.host {
  name = "desktop"; #!!! REPLACEME

  rice = "dark" #!!! REPLACEME

  # ...
}

Home Manager

If you created a constants module, just create a home.nix file with the following content:

{delib, pkgs, ...}:
delib.module {
  name = "home";

  home.always = {myconfig, ...}: let
    inherit (myconfig.constants) username;
  in {
    home = {
      inherit username;
      # If you don't need Nix-Darwin, or if you're using it exclusively,
      # you can keep the string here instead of the condition.
      homeDirectory =
        if pkgs.stdenv.isDarwin
        then "/Users/${username}"
        else "/home/${username}";
    };
  };
}

If you did not use the constants module, the content of the file will be:

{delib, pkgs, ...}:
delib.module {
  name = "home";

  home.always.home = {
    username = "sjohn"; #!!! REPLACEME
    # If you don't need Nix-Darwin, or if you're using it exclusively,
    # you can keep the string here instead of the condition.
    homeDirectory =
      if pkgs.stdenv.isDarwin
      then "/Users/sjohn" #!!! REPLACEME
      else "/home/sjohn"; #!!! REPLACEME
  };
}

User

You can also create a user.nix file with the configuration of your NixOS and Nix-Darwin user:

{delib, ...}:
delib.module {
  name = "user";

  # If you're not using NixOS, you can remove this entire block.
  nixos.always = {myconfig, ...}: let
    inherit (myconfig.constants) username;
  in {
    users = {
      groups.${username} = {};

      users.${username} = {
        isNormalUser = true;
        initialPassword = username;
        extraGroups = ["wheel"];
      };
    };
  };

  # If you're not using Nix-Darwin, you can remove this entire block.
  darwin.always = {myconfig, ...}: let
    inherit (myconfig.constants) username;
  in {
    users.users.${username} = {
      name = username;
      home = "/Users/${username}";
    };
  };
}

If you did not use the constants module, the content of the file will be:

{delib, ...}:
delib.module {
  name = "user";

  # If you're not using NixOS, you can remove this entire block.
  nixos.always.users = {
    groups.sjohn = {}; #!!! REPLACEME

    users.sjohn = { #!!! REPLACEME
      isNormalUser = true;
      initialPassword = "sjohn"; #!!! REPLACEME
      extraGroups = ["wheel"];
    };
  };

  # If you're not using Nix-Darwin, you can remove this entire block.
  darwin.always.users.users."sjohn" = { #!!! REPLACEME
    name = "sjohn"; #!!! REPLACEME
    home = "/Users/sjohn"; #!!! REPLACEME
  };
}

Conclusion

If you have followed the instructions precisely, you will end up with the following configuration directory tree:

hosts
- desktop
  - default.nix
  - hardware.nix
modules
- config
  - constants.nix
  - home.nix
  - hosts.nix
  - rices.nix
  - user.nix
rices
- dark
  - default.nix
flake.nix

You can check if everything is set up correctly using the command:

nix flake check .#