Modules vs imports

[pcasaretto]

Hi there!

On this section (https://nixos-and-flakes.thiscute.world/nixos-with-flakes/modularize-the-configuration), there is a mention to imports, but the linked documentation points to modules. Looking at the example it seems modules is the right parameter name. However, I have seen imports in several other places

• https://nixos.wiki/wiki/Home_Manager
• https://nixos.wiki/wiki/NixOS_modules

Can you ask you to enlighten me and explain these parameters?

[ryan4yin]

1. modules is a parameter of the function nixpkgs.lib.nixosSystem
2. imports is used in submodules to import other submodules.

[pcasaretto]

Where should the docs point to then? If modules is this https://github.com/NixOS/nixpkgs/blob/23.11/flake.nix#L24 It shouldn't point to https://nixos.org/manual/nixpkgs/unstable/#module-system-lib-evalModules, right?

Sorry if I'm being obtuse, I'm trying to wrap my head around this. Thanks again for the book. I've already learned a lot!

[pcasaretto]

Will modules = args.modules ++ [{ eventually find it's way into a lib.evalModules?

[ryan4yin]

Will modules = args.modules ++ [{ eventually find it's way into a lib.evalModules?

Yep, it's just part of the attrset passed into import ./nixos/lib/eval-config.nix：

https://github.com/NixOS/nixpkgs/blob/057f9aecfb71c4437d2b27d3323df7f93c010b7e/flake.nix#L22-L35

        nixosSystem = args:
          import ./nixos/lib/eval-config.nix (
            args // {
              modules = args.modules ++ [{
                system.nixos.versionSuffix =
                  ".${final.substring 0 8 (self.lastModifiedDate or self.lastModified or "19700101")}.${self.shortRev or "dirty"}";
                system.nixos.revision = final.mkIf (self ? rev) self.rev;
              }];
            } // lib.optionalAttrs (! args?system) {
              # Allow system to be set modularly in nixpkgs.system.
              # We set it to null, to remove the "legacy" entrypoint's
              # non-hermetic default.
              system = null;
            }
          );
      });

And nixos/lib/eval-config.nix is a wrapper of lib.evalModules:

https://github.com/NixOS/nixpkgs/blob/4a9a73c62698fc0f61a2f30aa8f843e45f929002/nixos/lib/eval-config.nix#L6-L8

# Ideally eval-config.nix would be an extremely thin wrapper
# around lib.evalModules, so that modular systems that have nixos configs
# as subcomponents (e.g. the container feature, or nixops if network
# expressions are ever made modular at the top level) can just use
# types.submodule instead of using eval-config.nix

[ryan4yin]

Closing this issue due to inactivity. Feel free to reopen if you are still have questions.

[pcasaretto]

Still trying to wrap my head around it, but you've made it clear. Thank you!