So in general it looks like this for me now:

[---SNIP---]
      sys = system: mods:
        nixpkgs.lib.nixosSystem {

          inherit system;
          
          specialArgs = {inherit inputs; } ;

          extraModules = [
            colmena.nixosModules.deploymentOptions
          ];
          
          modules = [
            self.nixosModule
            home-manager.nixosModules.home-manager

            ./common
          ] ++ mods;
        };

    in rec {

      colmena = {
        meta = {
          description = "My personal machines";
          nixpkgs = import nixpkgs {
            system = "x86_64-linux";
            overlays = [ nur.overlay ];
          };
        };

      } // builtins.mapAttrs (name: value: {
        nixpkgs.system = value.config.nixpkgs.system;
        imports = value._module.args.modules;
      }) (self.nixosConfigurations);
[---SNAP---]

In reply to @buckley310:matrix.org
i think my ideal scenario would be for nixosConfigurations to import the colmena module explicitly, and then nxiosConfigurations to be read directly by colmena... though i do not claim this to be an easy lift :D

I think it's a little weird to require nixpkgs to be set (because it requires a system set which may change at any point, depending on where you're deploying from). Sure, right now, I may be using x86_64-linux, but I may want to use aarch64-linux or some other arch at any time.

I would expect, if all of the target hosts have a matching nodeNixpkgs entry, that meta.nixpkgs wouldn't be required.

Even better, if it was combined with a deployment.nixpkgs option that replaces the meta.nodeNixpkgs option.

I may be able to work on this, if this is desired by more than just me.

IMHO, it makes more sense to configure the used nixpkgs inside of the node's config, instead of in the meta attrset.

See https://github.com/zhaofengli/colmena/issues/55.