Nix package set and NixOS module for using COSMIC. It is mainly a repository for testing COSMIC as it is developed.

Dedicated development matrix room: https://matrix.to/#/#cosmic:nixos.org

If you have an existing configuration.nix, you can use the nixos-cosmic flake with the following in an adjacent flake.nix (e.g. in /etc/nixos):

Note: If switching from traditional evaluation to flakes, nix-channel will no longer have any effect on the nixpkgs your system is built with, and therefore nixos-rebuild --upgrade will also no longer have any effect. You will need to use nix flake update from your flake directory to update nixpkgs and nixos-cosmic.

{
  inputs = {
    nixpkgs.follows = "nixos-cosmic/nixpkgs"; # NOTE: change "nixpkgs" to "nixpkgs-stable" to use stable NixOS release

    nixos-cosmic.url = "github:lilyinstarlight/nixos-cosmic";
  };

  outputs = { self, nixpkgs, nixos-cosmic }: {
    nixosConfigurations = {
      # NOTE: change "host" to your system's hostname
      host = nixpkgs.lib.nixosSystem {
        modules = [
          {
            nix.settings = {
              substituters = [ "https://cosmic.cachix.org/" ];
              trusted-public-keys = [ "cosmic.cachix.org-1:Dya9IyXD4xdBehWjrkPv6rtxpmMdRel02smYzA85dPE=" ];
            };
          }
          nixos-cosmic.nixosModules.default
          ./configuration.nix
        ];
      };
    };
  };
}

Note: To ensure binary substituters are set up before attempting to pull any COSMIC packages, perform a nixos-rebuild test with this configuration before attempting to add any COSMIC packages or settings to your NixOS configuration.

After setting up binary substituters and NixOS module, enable COSMIC with services.desktopManager.cosmic.enable = true and services.displayManager.cosmic-greeter.enable = true in your NixOS configuration.

To use COSMIC Store to manage Flatpaks, set services.flatpak.enable = true and then run flatpak remote-add --user flathub https://dl.flathub.org/repo/flathub.flatpakrepo in your user terminal to add the Flathub repository.

Although there is a provided binary cache built against the current nixos-unstable and nixos-24.05 branches, if you are not using a current nixos-unstable or nixos-24.05 then you may need to build packages locally.

Generally you will need roughly 16 GiB of RAM and 40 GiB of disk space, but it can be built with less RAM by reducing build parallelism, either via --cores 1 or -j 1 or both, on nix build, nix-build, and nixos-rebuild commands.

If while using an Nvidia GPU, cosmic-settings and cosmic-randr list show an additional display that can not be disabled, try Nvidia's experimental framebuffer device.

Add to your configuration:

boot.kernelParams = [ "nvidia_drm.fbdev=1" ];