Introduction to Denix Configurations (Flakes)

The delib.configurations function is used to create lists of nixosConfigurations, homeConfigurations, and darwinConfigurations for flakes.

In addition to all hosts, it also adds combinations of each host with every non-inheritanceOnly rice, which allows for quickly switching between rice configurations without editing the code. For example, if the "desktop" host is set to use the "light" rice, executing the following command:

nixos-rebuild switch --flake .#desktop --use-remote-sudo

will use the "desktop" host with the "light" rice. However, if you need to quickly switch to another rice, for example, "dark" you can run the following command:

nixos-rebuild switch --flake .#desktop-dark --use-remote-sudo

In this case, the host remains "desktop", but the rice changes to "dark".

It is important to note that when switching rice in this way, only the value of the ${myConfigName}.rice option changes, while the value of ${myConfigName}.hosts.${hostName}.rice remains the same.

Principle of Configuration List Generation

The configuration list is generated based on the following principle:

• {hostName} - where hostName is the name of any host.
• {hostName}-{riceName} - where hostName is the name of any host, and riceName is the name of any rice where inheritanceOnly is false.

If moduleSystem from the function arguments is set to home, then a prefix of {homeManagerUser}@ is added to all configurations in the list.

Example

An example of a flake's outputs for nixosConfigurations, homeConfigurations, and darwinConfigurations:

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

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

      specialArgs = {
        inherit inputs moduleSystem homeManagerUser;
      };
    };
in {
  nixosConfigurations = mkConfigurations "nixos";
  homeConfigurations = mkConfigurations "home";
  darwinConfigurations = mkConfigurations "darwin";
}

Using multiple channels

To conveniently work with multiple channels in the configuration, the delib.configurations function accepts the arguments nixpkgs, home-manager, and nix-darwin, which are used in the generated configurations.

By default, there is no need to specify these arguments - they default to the corresponding values from the Denix flake's inputs. These can also be overridden via inputs.denix.inputs.<input>.follows, which is more convenient for users who rely on a single channel.

Therefore:

• delib.configurations :: [nixpkgs, home-manager, nix-darwin] - for those who need multiple channels.
• inputs.denix.<nixpkgs|home-manager|nix-darwin>.follows - for those who only need a single channel.

Based on this, several usage options are possible:

1. Override nixpkgs, home-manager, and nix-darwin via the arguments of the delib.configurations function for both "stable" and "unstable" channels used in ./hosts/stable and ./hosts/unstable, respectively. Note that the implementation of the mkConfigurations function can vary - this is just an example.

{
  inputs = {
    nixpkgs-unstable.url = "github:nixos/nixpkgs/nixos-unstable";
    nixpkgs-stable.url = "github:nixos/nixpkgs/nixos-25.05";

    home-manager-unstable = {
      url = "github:nix-community/home-manager/master";
      inputs.nixpkgs.follows = "nixpkgs-unstable";
    };
    home-manager-stable = {
      url = "github:nix-community/home-manager/release-25.05";
      inputs.nixpkgs.follows = "nixpkgs-stable";
    };

    nix-darwin-unstable = {
      url = "github:nix-darwin/nix-darwin/master";
      inputs.nixpkgs.follows = "nixpkgs-unstable";
    };
    nix-darwin-stable = {
      url = "github:nix-darwin/nix-darwin/nix-darwin-25.05";
      inputs.nixpkgs.follows = "nixpkgs-stable";
    };

    denix.url = "github:yunfachi/denix";
  };

  outputs = {
    denix,
    nixpkgs-unstable,
    nixpkgs-stable,
    home-manager-unstable,
    home-manager-stable,
    nix-darwin-unstable,
    nix-darwin-stable,
    ...
  } @ inputs: let
    _mkConfigurations = nixpkgs: home-manager: nix-darwin: hosts: moduleSystem:
      denix.lib.configurations {
        inherit moduleSystem nixpkgs home-manager nix-darwin;
        homeManagerUser = "sjohn";

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

        specialArgs = {
          inherit inputs;
        };
      };

    mkConfigurations = moduleSystem:
      nixpkgs-unstable.lib.attrsets.mergeAttrsList 
      (map (f: f moduleSystem) [
        (_mkConfigurations nixpkgs-stable home-manager-stable nix-darwin-stable [./hosts/stable])
        (_mkConfigurations nixpkgs-unstable home-manager-unstable nix-darwin-unstable [./hosts/unstable])
      ]);
  in {
    nixosConfigurations = mkConfigurations "nixos";
    homeConfigurations = mkConfigurations "home";
    darwinConfigurations = mkConfigurations "darwin";
  };
}

2. Override nixpkgs, home-manager, and nix-darwin using inputs.denix.inputs.<name>.follows. This is the recommended method for those using a single channel.

{
  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";

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

    nix-darwin = {
      url = "github:nix-darwin/nix-darwin/master";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    denix = {
      url = "github:yunfachi/denix";
      inputs.nixpkgs.follows = "nixpkgs";
      inputs.home-manager.follows = "home-manager";
      inputs.nix-darwin.follows = "nix-darwin";
    };
  };

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

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

        specialArgs = {
          inherit inputs;
        };
      };
  in {
    nixosConfigurations = mkConfigurations "nixos";
    homeConfigurations = mkConfigurations "home";
    darwinConfigurations = mkConfigurations "darwin";
  };
}

3. Do not override anything. Also suitable for single-channel use, though less recommended.

{
  inputs = {
    denix.url = "github:yunfachi/denix";
  };

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

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

        specialArgs = {
          inherit inputs;
        };
      };
  in {
    nixosConfigurations = mkConfigurations "nixos";
    homeConfigurations = mkConfigurations "home";
    darwinConfigurations = mkConfigurations "darwin";
  };
}