Added copySysConf module.

options/copySysConf.nix

@@ -0,0 +1,49 @@
+{ config, pkgs, lib, ... }:
+
+with lib;
+
+let
+  cfg = config.system.copySysConf;
+  copySysConf = pkgs.stdenv.mkDerivation rec {
+    srcPath = ../.;
+    name = "NixOS_Configuration-${version}";
+    version = "0.1";
+    # this does not work yet for some reason
+    #    version = commitIdFromGitRepo "${srcPath}/.git";
+
+    src = cleanSource srcPath;
+
+    installPhase = ''
+      cp -R ./. $out
+    '';
+  };
+
+in {
+  options.system.copySysConf = {
+    enable = mkOption {
+      type = types.bool;
+      description = ''
+        Wether to copy the systems configuration.
+      '';
+    };
+    addToNixPath = mkOption {
+      type = types.bool;
+      description = ''
+        Use backup for nixos-rebuild.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    # probably don't need to add it to systemPackages
+    environment.systemPackages = [ copySysConf ];
+    nix = mkIf cfg.addToNixPath {
+      # Do not use lib.optionals as it would override the default nixPath
+      nixPath = [
+        "nixpkgs=/nix/var/nix/profiles/per-user/root/channels/nixos"
+        "nixos-config=${copySysConf}/configuration.nix"
+        "/nix/var/nix/profiles/per-user/root/channels"
+      ];
+    };
+  };
+}