--- Revision None
+++ Revision 663161613763
@@ -0,0 +1,29 @@
+# xen/manifests/init.pp
+
+[...]
+
+class xen::boot {
+    include grub
+    exec { "mv /etc/grub.d/10_linux /etc/grub.d/20_linux":
+        unless => "find /etc/grub.d -name 20_linux",
+        notify => Class["grub::update"]
+    }
+    exec { "mv /etc/grub.d/20_linux_xen /etc/grub.d/10_linux_xen":
+        unless => "find /etc/grub.d -name 10_linux_xen",
+        notify => Class["grub::update"]
+    }
+}
+
+
+# grub/manifests/init.pp
+
+[...] 
+ 
+class grub::update {
+    exec { "/usr/sbin/update-grub":
+   }
+}
+
+# error
+
+Could not run Puppet configuration client: Could not find dependent Class[Grub::Update] for Exec[mv /etc/grub.d/10_linux /etc/grub.d/20_linux] at /etc/puppet/modules/xen/manifests/init.pp:27