Generate colmena and hydraJobs outputs from the same hosts attribute set

hosts.nix

@@ -1,23 +1,27 @@
 { nixpkgs, nixpkgs-unstable, ... }:
 let
+  # Set of environment specific modules
   environments = {
     "proxmox" = [
       ./configuration/proxmox-vm
       ./configuration/proxmox-vm/hardware-configuration.nix
     ]; 
   };
+  # 
   generateDefaults = hosts: builtins.mapAttrs (name: {
     hostNixpkgs ? nixpkgs,
     system ? "x86_64-linux",
+    # pkgs is explicitly defined so that overlays for each host can easily be created
     pkgs ? hostNixpkgs.legacyPackages.${system},
     environment ? "proxmox",
     site
   }: {
     inherit hostNixpkgs system pkgs environment site;
+    # define common and host modules and additionally add environment specific modules
     modules = [
       ./configuration/common
       ./hosts/${name}
-    ] ++ (if environments ? ${environment} then environments.${environment} else []);
+    ] ++ environments.${environment};
   }) hosts;
 in
   generateDefaults {