Creating declarative containers programartically

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1

I’m trying to define some containers, while automating away some boilerplate. So I created a module that would take some container configs, and create the corresponding containers all in the same way. The following is actually a simplified version of it that only creates the first one:

{ lib, options, config, ... }: {
  options.local.containers = lib.mkOption {
    type = lib.types.listOf (lib.types.submodule {
      options = {
        name = lib.mkOption {
          type = lib.types.str;
        };
        config = lib.mkOption {
          type = lib.types.anything;
          description = "Container config";
        };
        options = lib.mkOption {
          type = lib.types.attrs;
          description = "Container options (see containers.<name>)";
          default = { };
        };
      };
    });
  };
  config = let
    id = 0;
    attrs = builtins.elemAt config.local.containers id;  # Take the first defined container
    name = attrs.name;
    options = attrs.options;
    ip_n3 = toString (100 + id);
  in {
    networking.hosts = {
      "192.168.${ip_n3}.1" = [ name ];
      "fe00::${ip_n3}:1" = [ name ];
    };
    containers.${name} = {
      config = {
        imports = [
          { # Add some additional things to the container config
            services.kresd.enable = lib.mkDefault true;
          }
          attrs.config
        ];
      };
      privateNetwork = true;
      localAddress = "192.168.${ip_n3}.1";
      hostAddress = "192.168.${ip_n3}.2";
      localAddress6 = "fc00::${ip_n3}:1";
      hostAddress6 = "fc00::${ip_n3}:2";
    } // options;
  };
}

I then tried to use it to create a container:

let
  container = { pkgs, ... }: {
    environment.systemPackages = [ pkgs.neovim ];
  };
in {
  local.containers = [{
    name = "test";
    config = container;
  }];
}

But when I try to build, I get an error:

nix-repl> nixosConfigurations.test-system.config.containers.test
{ additionalCapabilities = [ ... ]; allowedDevices = [ ... ]; autoStart = false; bindMounts = { ... }; config = error:
       … while evaluating the attribute 'value'

         at /nix/store/qkzr5clkyq7j6n43qs5ff73in6c3wacv-source/lib/modules.nix:809:9:

          808|     in warnDeprecation opt //
          809|       { value = builtins.addErrorContext "while evaluating the option `${showOption loc}':" value;
             |         ^
          810|         inherit (res.defsFinal') highestPrio;

       … while calling the 'addErrorContext' builtin

         at /nix/store/qkzr5clkyq7j6n43qs5ff73in6c3wacv-source/lib/modules.nix:809:17:

          808|     in warnDeprecation opt //
          809|       { value = builtins.addErrorContext "while evaluating the option `${showOption loc}':" value;
             |                 ^
          810|         inherit (res.defsFinal') highestPrio;

       (stack trace truncated; use '--show-trace' to show the full trace)

       error: function 'container' called without required argument 'pkgs'

       at /nix/store/dn9czq0mv21h45nzkc3qghfhy9hvjvjj-source/systems/modules/test-container.nix:2:15:

            1| let
            2|   container = { pkgs, ... }: {
             |               ^
            3|     environment.systemPackages = [ pkgs.neovim ];

I have no idea what is going wring here. attrs.config is a lambda function that’s a module, and I’d think that, when added to the container imports, would be treated as a module. But that doesn’t seem to happen for some reason, and I have no idea how to debug further.