add initial nixos mylib

lib/default.nix

@@ -0,0 +1,5 @@
+{ inputs, pkgs, lib, ... }:
+
+rec {
+  nixos = import ./nixos.nix;
+}

lib/nixos.nix

@@ -0,0 +1,47 @@
+{ inputs, pkgs, lib, ... }:
+
+let
+
+  # Allows to just use nixpkgs without qualifiers
+  inherit (inputs) nixpkgs;
+
+in rec {
+  mkNixosConfig = { system, hostname, extraModules, homeManagerConfig }:
+  nixpkgs.lib.nixosSystem {
+    inherit system;
+
+    # Make our inputs available to the configuration.nix (for importing modules)
+    specialArgs = { inherit inputs; };
+
+    modules = builtins.conatLists [
+      [
+        # Replace the pkgs to include overlays/unfree
+        { nixpkgs.pkgs = pkgs; }
+
+        # Main config file for all configs/hosts
+        ./nixos/configuration.nix
+
+        # Host specifig config file
+        (import "./nixos/configuration-" + hostname + ".nix")
+      ]
+      extraModules
+      homeManagerConfig
+    ];
+  };
+
+  mkHomeManagerConfig = { username }:
+  home-manager.nixosModules.home-manager
+  {
+    # Use systems pkgs, disables nixpkgs.* options in home.nix
+    home-manager.useGlobalPkgs = true;
+
+    # Enable installing packages through users.christoph.packages to /etc/profiles instead of ~/.nix-profile
+    home-manager.useUserPackages = true;
+
+    # User specific config file
+    home-manager.users.username = import "./home/home-" + username + ".nix";
+
+    # Include the inputs just in case they might be needed somewhere
+    home-manager.extraSpecialArgs = { inherit inputs; };
+  };
+}