nixpkgs: init config as separate file

common/default.nix

@@ -5,6 +5,7 @@
     ./environment.nix
     ./home-manager.nix
     ./nginx.nix
+    ./nixpkgs.nix
     ./openssh.nix
     ./security.nix
     ./zsh.nix

common/nixpkgs.nix

@@ -0,0 +1,14 @@
+{ config, lib, pkgs, inputs, ... }:
+
+{
+  nixpkgs = {
+    config = {
+      allowUnfree = true;
+      packageOverrides = pkgs: {
+        agenix = inputs.agenix.packages.${config.nixpkgs.hostPlatform.system}.default;
+      };
+    };
+
+    overlays = [ inputs.nur.overlay ];
+  };
+}

flake.nix

@@ -27,25 +27,15 @@
         nodeNixpkgs = {
           kalessin = import nixpkgs { system = "aarch64-linux"; }; # TODO: this should be generated from the host config somehow
         };
+        specialArgs = {
+          inherit inputs;
+        };
       };
 
-      defaults = { name, nodes, config, lib, pkgs, ... }: {
+      defaults = { name, nodes, ... }: {
         networking.hostName = name;
 
         nix.settings.experimental-features = "nix-command flakes";
-        nixpkgs.flake.source = nixpkgs;
-        nix.nixPath = [ "nixpkgs=flake:nixpkgs" ];
-
-        nixpkgs = {
-          config = {
-            allowUnfree = true;
-            packageOverrides = pkgs: {
-              agenix = agenix.packages.${config.nixpkgs.hostPlatform.system}.default;
-            };
-          };
-
-          overlays = [ nur.overlay ];
-        };
 
         imports = [
           home-manager.nixosModules.home-manager