spilt pgk and config

module/etherpad/etherpad-pkg.nix

@@ -0,0 +1,18 @@
+{ stdenv, fetchFromGitHub }:
+
+stdenv.mkDerivation rec {
+  name= "etherpad-${version}";
+  version = "1.6.2";
+
+  src = fetchFromGitHub {
+    owner = "ether";
+    repo = " etherpad-lite";
+    rev = "${version}";
+    sha256 = "1zzx851603apysmzgxn6zqg779yak8r5vnafycy454wcgq6lb0bf";
+  };
+
+  installPhase = ''
+    mkdir -p $out/
+    cp -R . $out/
+  '';
+}

module/etherpad/etherpad.nix

@@ -1,6 +1,8 @@
 { config, lib, pkgs, ... }:
 
 {
+  imports =  [ ./etherpad-pkg.nix ];
+  
   ###### interface
 
   options = {
@@ -33,22 +35,3 @@
       };
   };
 }
-
-{ stdenv, fetchFromGitHub }:
-
-stdenv.mkDerivation rec {
-  name= "etherpad-${version}";
-  version = "1.6.2";
-
-  src = fetchFromGitHub {
-    owner = "ether";
-    repo = " etherpad-lite";
-    rev = "${version}";
-    sha256 = "1zzx851603apysmzgxn6zqg779yak8r5vnafycy454wcgq6lb0bf";
-  };
-
-  installPhase = ''
-    mkdir -p $out/
-    cp -R . $out/
-  '';
-}