Sometimes NixOS modules need to be used in configuration but exist outside of Nixpkgs. These modules can be imported: { config, lib, pkgs, ... }: { imports = [ # Use a locally-available module definition in # ./example-module/default.nix ./example-module ]; services.exampleModule.enable = true; } The environment variable NIXOS_EXTRA_MODULE_PATH is an absolute path to a NixOS module that is included alongside the Nixpkgs NixOS modules. Like any NixOS module, this module can import additional modules: # ./module-list/default.nix [ ./example-module1 ./example-module2 ] # ./extra-module/default.nix { imports = import ./module-list.nix; } # NIXOS_EXTRA_MODULE_PATH=/absolute/path/to/extra-module { config, lib, pkgs, ... }: { # No `imports` needed services.exampleModule1.enable = true; }