Recursive error when setting pkgs path

Help
1

Hi!

I want to upgrade my <nixpkgs> to get nushell latest version for a project I’m working on but I’m not able to set a path to <nixpkgs> since I’m building my configuration from a configuration.nix file located in another place to track it with git more easily.

I followed this answer to troubleshoot but I get the following error:

~/waves_nixconfig> sudo nixos-rebuild switch --upgrade
unpacking 2 channels...
error:
       … while evaluating the attribute 'config'
         at /nix/store/22d94ry10ivvac4z97713iw3wr78icxl-nixos-25.11/nixos/lib/modules.nix:361:9:
          360|         options = checked options;
          361|         config = checked (removeAttrs config [ "_module" ]);
             |         ^
          362|         _module = checked (config._module);

       … while calling the 'seq' builtin
         at /nix/store/22d94ry10ivvac4z97713iw3wr78icxl-nixos-25.11/nixos/lib/modules.nix:361:18:
          360|         options = checked options;
          361|         config = checked (removeAttrs config [ "_module" ]);
             |                  ^
          362|         _module = checked (config._module);

       … while evaluating the module argument `inputs' in "/home/wavesinaroom/waves_nixconfig/configuration.nix":

       … noting that argument `inputs` is not externally provided, so querying `_module.args` instead, requiring `config`

       … if you get an infinite recursion here, you probably reference `config` in `imports`. If you are trying to achieve a conditional import behavior dependent on `config`, consider importing unconditionally, and using `mkEnableOption` and `mkIf` to control its effect.

       (stack trace truncated; use '--show-trace' to show the full, detailed trace)

       error: infinite recursion encountered
Command 'nix-build '<nixpkgs/nixos>' --attr config.system.build.nixos-rebuild --no-out-link' returned non-zero exit status 1.

The infinity recursion happens also with this command sudo nixos-rebuild switch -I nixos-config=~/waves_nixconfig/configuration.nix which is expected.

I managing my NixosWSL config with a flake that pins <nixpkgs> unstable and calls my configuration.nix file as a module the way we all are familiar with. I’m a bit confused about how to set <nixpkgs> path so I’d like ask for help but more importantly for reasons why infinite recursion happen. There’s some info here but I want to ask the community first to not to fall into a rabbit hole that delays my Nushell project for a long time.

~/waves_nixconfig/flake.nix

{
  description = "Waves in a room set up";
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    nixos-wsl.url = "github:nix-community/NixOS-WSL/main";
    home-manager = {
      url = "github:nix-community/home-manager/release-25.11";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };
  outputs =
    { nixpkgs, ... }@inputs:
    {
      nixosConfigurations."desktop" = nixpkgs.lib.nixosSystem {
        specialArgs = { inherit inputs; };
        modules = [ ./configuration.nix ];
      };
    };
}

~/waves_nixconfig/configuration.nix

{
  inputs,
  pkgs,
  config,
  ...
}:
{
  imports = [
    inputs.nixos-wsl.nixosModules.default
    inputs.home-manager.nixosModules.home-manager
    ./hardware-configuration.nix
  ];

  wsl.enable = true;
  wsl.defaultUser = "wavesinaroom";
  wsl.wslConf.network.hostname = "desktop";
  nix.settings.experimental-features = [
    "nix-command"
    "flakes"
  ];
  nix.nixPath = [
    "nixpkgs=/nix/var/nix/profiles/per-user/root/channels/nixos"
    "nixos-config=${config.users.users.wavesinaroom.home}/waves_nixconfig/configuration.nix"
    "/nix/var/nix/profiles/per-user/root/channels"
  ];
}
2

Since ~/waves_nixconfig is a flake, have you tried sudo nixos-rebuild switch --flake ~/waves_nixconfig?

3

Yeah, I don’t get any error when I run that command but it doesn’t upgrade my packages to their latest version on unstable.

4

To upgrade a flake’s inputs, you need to run nix flake update (you can add --commit-lock-file if you’re using git).

The --upgrade argument to nixos-rebuild doesn’t update flakes.

5

Thanks a lot! It’s upgrading now. Do you have a suggested reading I should go through to understand why this happened?