NixOS config is

{ config, lib, pkgs, modulesPath, home-manager, ... }:
{
  deployment = {
    targetHost = "192.168.x.y";
    targetUser = "nixos";
    tags = [ "rpi" "lab" ];
  };

  imports = [
    (home-manager + "/nixos")
  ];
}

In reply to @zhaofeng:zhaofeng.li
What does your hive.nix look like?

Sorry for not replying earlier, but I don't have a hive.nix, just a flake.nix as follows:

{
  description = "Flake for RPI 4 Lab Infrastructure";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-21.05";
    devshell.url = "github:numtide/devshell";
    flake-utils.url = "github:numtide/flake-utils";
    colmena.url = "github:zhaofengli/colmena/v0.2.0";
    colmena.inputs.utils.follows = "flake-utils";
    home-manager.url = "github:nix-community/home-manager/release-21.05";
    home-manager.inputs.nixpkgs.follows = "nixpkgs";
  };
  outputs = { self, nixpkgs, devshell, flake-utils, colmena, home-manager }:
    let
      nativePkgs = import nixpkgs { 
        system = ( if builtins ? currentSystem then builtins.currentSystem else "x86_64-linux" );
        };
    in
    {
      colmena = {
        meta.nixpkgs = nativePkgs;
        pi = import ./pi4.nix;
        specialArgs = {
          inherit home-manager;
        };
      };
    } // flake-utils.lib.eachDefaultSystem
      (system:
        let 
          pkgs = import nixpkgs { inherit system; overlays = [ devshell.overlay ]; };
        in
        {
          devShell = pkgs.devshell.mkShell {
            packages = with pkgs; [
              colmena.defaultPackage.${system}
            ];
          };
        }
      );
}

In reply to @zhaofeng:zhaofeng.li
Is home-manager there as part of the NixOS module arguments? That shouldn't have worked.

In reply to @necrophcodr:matrix.org
Yea, it is

It's in fact an older version of colmena as well, where I've got

meta = { inherit nixpkgs; };

So the flake.nix is simple:

{
  description = "NixOS Flake for NixOps deployment of dashboards";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-21.05";
    flake-utils.url = "github:numtide/flake-utils";
    devshell.url = "github:numtide/devshell";
    colmena.url = "github:zhaofengli/colmena";
    home-manager.url = "github:nix-community/home-manager/release-21.05";
  };

  outputs = { self, nixpkgs, flake-utils, devshell, colmena, home-manager }:
    {
      colmena = {
        meta = {
          inherit nixpkgs;
        };		# ... Nodes ...
      };
    } // flake-utils.lib.eachDefaultSystem
      (system:
        let 
          pkgs = import nixpkgs {
            inherit system;
            overlays = [ devshell.overlay ];
          };
        in
		...
}

# Edit this configuration file to define what should be installed on
# your system.  Help is available in the configuration.nix(5) man page
# and in the NixOS manual (accessible by running ‘nixos-help’).

{ config, lib, pkgs, modulesPath, ... }:
{
  deployment = {
    targetHost = "x.x.x.x";
  };
  networking.hostName = "HOST";
  home-manager.users.su = { pkgs, ... }: {
    home.file."dash.sh".source = dashFile;
  };
  imports =
    [
      ../lib/dashboard.nix
      ../lib/wifi.nix
    ];
...
}

So that's the node.nix file

And then we've got the ../lib/dashboard.nix file that contains

{ config, lib, pkgs, modulesPath, home-manager, ... }:
{
  deployment.targetUser = "su";
  imports = [
    (modulesPath + "/installer/scan/not-detected.nix")
    (home-manager + "/nixos" )
  ];
...
}

# Edit this configuration file to define what should be installed on
# your system.  Help is available in the configuration.nix(5) man page
# and in the NixOS manual (accessible by running ‘nixos-help’).

{ config, lib, pkgs, modulesPath, ... }:
let
  dashFile = "some_file.txt";
in
{
  deployment = {
    targetHost = "x.x.x.x";
  };
  networking.hostName = "HOST";
  home-manager.users.su = { pkgs, ... }: {
    home.file."dash.sh".source = dashFile; # dashFile is a variable declared above
  };
  imports =
    [
      ../lib/dashboard.nix
      ../lib/wifi.nix
    ];
...
}

So that's the node.nix file