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Setting "global" options from a submodule? (lemmy.ml)

submitted 1 year ago* (last edited 1 year ago) by [email protected] to c/[email protected]

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I'd like to set a "global" option from within a submodule, but the config I return is grafted into the "global" under the submodule "path" rather than at the root... any idea if it's somehow possible?

Er... I guess I didn't make a great job at explaining what I want to do... Some code will hopefully help.

In mymodule.nix I have:

{ lib, config, ... }: {

  options.myoption = lib.mkOption {
      type = lib.types.attrsOf (lib.types.submodule (
        import ./mysubmodule.nix
      ));
  };

}

and mysubmodule.nix is:

{ name, lib, config, ... }: {

options.mysubmoduleoption = {
  type = lib.types.str;
};

config = {
  # here I want to set a "global" option, say "systemd.mounts"
  # based on the value of "mymodule.name.mysubmoduleoption"
  # but it seems I can only set values under "mymodule.name" 
};

}

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[–] [email protected] 1 points 1 year ago (1 children)

It doesn't work like that. Submodules are for defining the type, so the only thing you get is interface (options), not implementation.

I know I can restructure the code in other ways (eg. let .. in)

Do that.

Also be aware that some use-cases might be covered by library functions such as lib.flatMap or lib.pipe.

[–] [email protected] 1 points 1 year ago

Submodules are for defining the type, so the only thing you get is interface (options), not implementation.

You do get a functional config in submodules... try this (it doesn't do anything so you can just import into any configuration.nix):

{ config, lib, pkgs, modulesPath, specialArgs, options, ... }: {

  options.mynamespace = lib.mkOption {
    type = lib.types.attrsOf (lib.types.submodule ({name, config, ...}:{
      options = {
        option1 = lib.mkOption { type = lib.types.str; default = ""; };
        option2 = lib.mkOption { type = lib.types.str; default = ""; };
      };
      config = {
        option2 = "derived from value of option1: '${config.option1}'";
      };
    }));
  };

  config = {

    mynamespace.submodule1.option1 = "value of option1";

    fileSystems = builtins.trace (builtins.toJSON config.mynamespace) {};

  };

}