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" 
};

}
  • Atemu
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    1 year ago

    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.

    • gompOP
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      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) {};
      
        };
      
      }