Add text files to configuration.nix

Hi all,

I am new to NixOS and as everyone I have to manage my configuration.nix file.

I have a question on how to write on it and arrange it. Is it possible, and is it advised, to put some settings in a separated file (I don’t know, for example packages for a specific user) and add it to the “main” configuration file, in the same way it is sometimes done for the bash_aliases added to bash_rc ?

If I understand correctly, you are asking about modularizing your nixos config, splitting it into multiple files.

It is possible.

First, the way you probably want to do it:

There exists a special imports field for all modules in the nixpkgs module system. All file paths you add there will be merged into the configuration

# module_a.nix

{ pkgs, lib, ...}: {
  environment.systemPackages = with pkgs; [ hello ];
# configuration.nix
{ pkgs, lib, ...} : {
  imports = [./module-a.nix];
  environment.systemPackages = with pkgs; [ world ];

  # in the final config, environment.systemPackages will be [hello world]

Second, the nix language itself provides an import keyword that can bind the nix expression from one file to a variable.


# a.nix

## a function that returns 2
{}: 2
# b.nix

let a = import ./a.nix; in (a {}) +2

### this file will evaluate to 2+2=4

Thanks a lot !

It is very clear and it seems to be what I was searching for.

There is just a small typo :

instead of

imports = [./module_a.nix];

Anyway, thanks again !