I’m pretty new to nix and have setup home manager according to this guide: Getting Started with Home Manager | NixOS & Flakes Book. However i have several machines that runs nixos and want to configure them all to use the same home-manager configuration. Currently it looks like this nixos-config/flake.nix at 7733dea1f1f1e5c95104267cbb09365f3f3ff45e · zlepper/nixos-config · GitHub with the home manager configuration repeated for every single host, which seems a bit wasteful.
I have tried moving the configuration out into a let block before the nixosConfiguration blocks like this:
let
...
homeMgr = home-manager.nixosModules.home-manager
{
home-manager.useGlobalPkgs = true;
home-manager.useUserPackages = true;
home-manager.users.rasmus = import ./home.nix;
home-manager.extraSpecialArgs = {
unstable = unstablePkgs;
writerside = writersidePrPkgs;
};
};
in {
...
nixosConfigurations.home-laptop = nixpkgs.lib.nixosSystem {
system = "x86_64-linux";
specialArgs = inputs;
modules = [
./home-laptop.nix
homeMgr
];
};
};
}
However when i run that i get this error:
error:
… while calling the 'seq' builtin
at /nix/store/9xacbyc7dywnxssdz5xc2nyi7pj0hw3k-source/lib/modules.nix:320:18:
319| options = checked options;
320| config = checked (removeAttrs config [ "_module" ]);
| ^
321| _module = checked (config._module);
… while evaluating a branch condition
at /nix/store/9xacbyc7dywnxssdz5xc2nyi7pj0hw3k-source/lib/modules.nix:261:9:
260| checkUnmatched =
261| if config._module.check && config._module.freeformType == null && merged.unmatchedDefns != [] then
| ^
262| let
(stack trace truncated; use '--show-trace' to show the full trace)
error: function 'anonymous lambda' called without required argument 'config'
at /nix/store/9613fxrf433y10fz18ccixj4zpmdibzq-source/nixos/default.nix:1:1:
1| { config, lib, pkgs, utils, ... }:
| ^
2|
I assume this has to do with the modules being called in a rather special way that i cannot use in the let block, however i’m a bit lost as to how to proceed from there?
Hey,
you need to write a module, i recommend you follow this wiki entry.
The main thing is that a module consists of a config, option and an optional imports block.
For your case this could look something like this:
# home-manager-module.nix
{ lib, config, ... }:
with lib;
{
options.my-option.enable = mkEnableOption "enable home manager with my settings";
config = mkIf config.my-option.enable {
home-manager = {
useGlobalPkgs = true;
useUserPackages = true;
# I would put this elsewhere
# users.rasmus = import ./home.nix;
};
}
# flake.nix
{
...
nixosConfigurations.home-laptop = nixpkgs.lib.nixosSystem {
system = "x86_64-linux";
specialArgs = inputs;
modules = [
./home-laptop.nix
./home-manager-module.nix
];
};
# configuration.nix
{
...
my-option.enable = true
...
}
I hope that was helpful, feel free to ask follow-ups :]
1 Like
Thank you so much for taking the time to reply, it is extremely appreciated 
I have now tried splitting it out like you suggest (Which is also would i would really like to be my final-endgoal). Current attempt can be seen in this commit: Draft 1 for using home manager from a module · zlepper/nixos-config@f6b5295 · GitHub.
However now i get an error that the option home-manager does not exist:
error:
… while calling the 'seq' builtin
at /nix/store/9xacbyc7dywnxssdz5xc2nyi7pj0hw3k-source/lib/modules.nix:320:18:
319| options = checked options;
320| config = checked (removeAttrs config [ "_module" ]);
| ^
321| _module = checked (config._module);
… while calling the 'throw' builtin
at /nix/store/9xacbyc7dywnxssdz5xc2nyi7pj0hw3k-source/lib/modules.nix:296:18:
295| ''
296| else throw baseMsg
| ^
297| else null;
error: The option `home-manager' does not exist. Definition values:
- In `/nix/store/bc950b2x0wh3ffv27wwl5cs8sda6if2i-source/home-manager-module.nix':
{
_type = "if";
condition = true;
content = {
useGlobalPkgs = true;
...
(I have imported the home.nix file directly in the module for now, before i start messing with making it somewhat dynamic, just to only have one thing to be confused about at a time 
)
EDIT: Actually, think i got something working, just a second!
Alright, got it working!
The thing that was “tricking” me here, is that home-manager.nixosModules.home-manager is a nix module, not a function as I originally thought. Then the block after
{
home-manager.useGlobalPkgs = true;
home-manager.useUserPackages = true;
home-manager.users.rasmus = import ./home.nix;
home-manager.extraSpecialArgs = {
unstable = unstablePkgs;
writerside = writersidePrPkgs;
};
};
is also a module, not an argument to that function.
Thus the thing that was missing from @lovirent’s suggestion was just to actually import the home manager module, either in the flake.nix file or in the new home-manager-module.nix file:
{lib, config, unstable, writerside, home-manager, ...}:
{
imports = [home-manager.nixosModules.home-manager];
options.use-home-manager.enable = lib.mkEnableOption "enable home manager with my settings";
config = lib.mkIf config.use-home-manager.enable {
home-manager = {
useGlobalPkgs = true;
useUserPackages = true;
# I would put this elsewhere
users.rasmus = import ./home.nix;
extraSpecialArgs = {
inherit unstable writerside;
};
};
};
}
Full diff for anyone who comes from the future and need the entire context: Comparing f6b52958e7536b15d146fea846b1d2021b89e9ab..6bcc171d94af2561299324b16a7ee924599f7ce5 · zlepper/nixos-config · GitHub
woopsie,
glad to be of any help tho 
1 Like