Generate random keystone users

Change-Id: I8dbd07b10d29b43d1c35fa76bcaa0f0efb32beda
Related-Prod: PROD-29868
diff --git a/gnocchi/server/cluster.yml b/gnocchi/server/cluster.yml
index 1ad5e44..8e3265e 100644
--- a/gnocchi/server/cluster.yml
+++ b/gnocchi/server/cluster.yml
@@ -17,6 +17,8 @@
         metric_processing_delay: 15
         metric_reporting_delay: 30
       identity:
+        user: ${_param:keystone_gnocchi_username}
+        password: ${_param:keystone_gnocchi_password}
         host: ${_param:openstack_control_address}
         region: ${_param:openstack_region}
         protocol: ${_param:cluster_internal_protocol}