question: is it possible to reference the home-manager configuration as a standalone flake?

[dbkegley]

I'm very new to nix and I'm still trying to learn how the ecosystem fits together so thank you so much for going through the effort to document and share your configuration, it has been an extremely helpful learning tool.

My setup differs from yours a little bit because I have some linux environments where I don't use NixOS (I plan to but would like to start with home-manager initially) so I would like to be able to re-use the shared home-manager configuration as a standalone tool.

I'm hoping you might be able to point me in the right direction, or at least tell me if what I'm trying to accomplish is possible.

I would like to have something like this:

# flake.nix
...
darwinConfigurations = {
  david-mbp = darwin.lib.darwinSystem {
    specialArgs = {
      inherit inputs outputs;
      lib = lib "${systemDarwin}";
    };
    modules = sharedModules ++ darwinModules ++ [ ./machines/darwin/default.nix ];
  };
};

homeConfigurations = {
  <hostname> = home-manager.lib.homeManagerConfiguration {
    pkgs = nixpkgs.legacyPackages.${systemLinux};
    extraSpecialArgs = {
      inherit inputs outputs;
      sharedLib = lib "${systemLinux}";
      imports = [ ./machines/common/default.nix ];
    };
    modules = sharedModules;
  };
};

# nixosConfigurations = {
#   legion = nixpkgs.lib.nixosSystem {
#     specialArgs = {
#       inherit inputs outputs;
#       lib = lib "x86_64-linux";
#     };
#     modules = sharedModules ++ nixosModules ++ [ ./machines/legion/default.nix ];
#   };
...

So that I can install it as a flake anywhere home-manager is installed without requiring nixos/nix-darwin:

home-manager switch --flake .#<hostname>

Is that possible with the way these modules are structured today or do I need to create an intermediate module that serves as a replacement for nixpkgs.lib.nixosSystem / darwin.lib.darwinSystem in order to call home-manager this way?

[dc-tec]

Thanks for taking the time to create an issue and great to hear it helps you learn more about Nix (I'm still learning myself :) ).

It should be possible to use home-manager.lib.homeManagerConfiguration directly using the sharedModules. You might have to tweak some options tho (at least that is what I expect).

Have you tried this already by chance? However I haven't used it in this way using home-manager directly, but I'm interested to know if you can get it working.

Feel free to share any error message you might encounter and I'm happy to help if needed.

[dbkegley]

That would be great if you don't mind taking a look and giving some pointers!

Here's what I have currently in my flake.nix:

     homeConfigurations = {
        home = home-manager.lib.homeManagerConfiguration {
          pkgs = nixpkgs.legacyPackages.${systemLinux};
          extraSpecialArgs = {
            inherit inputs outputs;
            lib = lib "${systemLinux}";
            imports = [ ./machines/wsl2/default.nix ];
          };
          modules = [ ./modules/shared ] ;
        };
      };

And this is the error I'm getting now:

➜  nix git:(main) home-manager switch --flake .#home
error:
       … while evaluating a branch condition
         at /nix/store/9x1a429wj6sy54bfr028820n5mgyvdri-source/lib/lists.nix:142:18:
          141|       len = length list;
          142|       fold' = n: if n == len then nul else op (elemAt list n) (fold' (n + 1));
             |                  ^
          143|     in

       … while calling the 'length' builtin
         at /nix/store/9x1a429wj6sy54bfr028820n5mgyvdri-source/lib/lists.nix:141:13:
          140|     let
          141|       len = length list;
             |             ^
          142|       fold' = n: if n == len then nul else op (elemAt list n) (fold' (n + 1));

       … while evaluating the module argument `pkgs' in "/nix/store/v4gwzpjymz6sfbzx3k0q8mkjgr5f77p9-source/modules/programs/k9s.nix":

       … while evaluating the module argument `pkgsPath' in "/nix/store/v4gwzpjymz6sfbzx3k0q8mkjgr5f77p9-source/modules/misc/nixpkgs.nix":

       … while evaluating the option `home.stateVersion':

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

       error: The option `home.stateVersion' was accessed but has no value defined. Try setting the option

So it seems that the options from machines/wsl2/default.nix are not getting loaded properly.

Also, in the home-manager configuration I had to rename lib to sharedLib because otherwise it steps on the home-manager's lib namespace:

       error: attribute 'hm' missing
       at /nix/store/v4gwzpjymz6sfbzx3k0q8mkjgr5f77p9-source/modules/services/mako.nix:96:8:
           95|     ]
           96|     ++ lib.hm.deprecations.mkSettingsRenamedOptionModules basePath (basePath ++ [ "settings" ]) {
             |        ^
           97|       transform = lib.hm.strings.toKebabCase;
       Did you mean one of id or or?

My full configuration is here - I've tried to keep it as minimal as possible for now so there's quite a bit of code that is commented out until I figure out what each piece actually does.

[dc-tec]

What we could do is the following, in your flake.nix try this:

homeConfigurations = {
  home = home-manager.lib.homeManagerConfiguration {
    pkgs = nixpkgs.legacyPackages.${systemLinux};
    extraSpecialArgs = {
      inherit inputs outputs;
      sharedLib = lib "${systemLinux}";
      imports = [ ./machines/wsl2/default.nix ];
    };
    modules = [
      {
        home = {
          stateVersion = "^YOUR_STATEVERSION^";
          username = "^YOUR_USERNAME^";
          homeDirectory = "^YOUR_HOMEDIRECTORY^";
        };
      }
      ./modules/shared/config
      ./modules/shared/utils
      ./modules/shared/development
    ];
  };
};

What we do is omit the home-manager module in shared-modules and directly set the values that we want and then only import the shared modules that will work in standalone mode.

Not sure if this will work, but worth a shot.

Digging a bit deeper, the shared module contains quite a few settings/configurations that will only work on NixOS/Darwin (i.e. system.nix in shared modules).

[dc-tec]

Probably to fix this permanently and be able to include the whole shared module you might want to create some conditional logic that includes/excludes certain configurations like I did with isLinux / isDarwin.