Add MkSystem function to lib.

nixos/lib/default.nix

@@ -1,4 +1,5 @@
 {
   utils = import ./utils.nix;
   getSSHKeys = (import ./keys.nix).getSSHKeys;
+  mkSystem = (import ./nixos.nix).mkSystem;
 }

nixos/lib/nixos.nix

@@ -0,0 +1,25 @@
+let
+  foelib = import ./default.nix;
+in {
+  mkSystem = nixpkgs: pkgs: hostname: modules:
+    nixpkgs.lib.nixosSystem {
+      modules =
+        [
+          {
+            nix.registry = {
+              nixpkgs.flake = nixpkgs;
+              p.flake = nixpkgs;
+            };
+            nixpkgs.pkgs = pkgs;
+
+            networking.hostname = hostname;
+          }
+        ]
+        ++ modules
+        ++ foelib.utils.findNixFiles ../nixos;
+
+      specialArgs = {
+        inherit hostname foelib;
+      };
+    };
+}