Manually add dependencies between "devices"?

[nazarewk]

Problem

I have a LUKS disk using a zfs_volume as detached header. disko-format script generates those in the wrong order.

Expected solution

I would expect to be able to manually create the missing dependencies in cases when they are missing

Context

I have found a _meta.deviceDependencies, which seems to be what I need, but unfortunately, this is not available for overriding (is both readOnly and a function).

Is there any other way I can make it work?

[nazarewk]

I made this "cursed" setup that adds proper merging mechanisms:

{
  lib,
  config,
  options,
  pkgs,
  ...
}: {
  # define a properly merge-able option, there might be something better than JSON, but it works well
  options.kdn.disks.disko.devices._meta = lib.mkOption {
    type = (pkgs.formats.json {}).type;
    default = {};
  };

  config = lib.mkMerge [
    {
      # PLUMBING

      # extract the default value from option's definition
      kdn.disks.disko.devices._meta = options.disko.devices.valueMeta.configuration.options._meta.default;
      # set the non-mergable `disko.devices._meta` with a properly merged value
      disko.devices._meta = config.kdn.disks.disko.devices._meta;
    }
    {
      # USAGE
      # can be defined anywhere else

      kdn.disks.disko.devices._meta.deviceDependencies = {
        disk.data-pwet = [
          ["zpool" "pwet-main"]
        ];
      };
    }
  ];
}

1. Maybe we could just set type = (pkgs.formats.json {}).type; on the _meta definitions themselves?
2. Maybe we could drop the readOnly = true; from the codebase and set the "defaults" under actual config keys?