Improvements to OpenStack inventory script

plugins/inventory/nova.ini

@@ -14,7 +14,7 @@ api_key       =
 auth_url      =
 
 # Authentication system
-auth_system =
+auth_system = keystone
 
 # OpenStack nova project_id
 project_id    = 
@@ -22,6 +22,13 @@ project_id    =
 # Serverarm region name to use
 region_name   =
 
+# Specify a preference for public or private IPs (public is default)
+prefer_private = False
+
+# What service type (required for newer nova client)
+service_type = compute
+
+
 # TODO: Some other options
 # insecure      =
 # endpoint_type =