Horizon iptables rules

Releated-Prod: PROD-23525

Change-Id: Ib562b1d4cfa7d8df87b06b60d8d7ccf5ff4db4c3
diff --git a/horizon/server/cluster.yml b/horizon/server/cluster.yml
index 0cd20d7..db0c7e5 100644
--- a/horizon/server/cluster.yml
+++ b/horizon/server/cluster.yml
@@ -1,6 +1,7 @@
 classes:
 - service.keepalived.cluster.single
 - service.horizon.server.cluster
+- system.horizon.server.iptables
 - service.haproxy.proxy.single
 - system.apache.server.single
 - system.haproxy.proxy.listen.openstack.horizon