Add system.prometheus.server.alertmanager.dns

Change-Id: I25ecdadfa1b854053e98f553bf6acacb0c37edd9
diff --git a/classes/cluster/virtual-mcp11-k8s-contrail/stacklight/server.yml b/classes/cluster/virtual-mcp11-k8s-contrail/stacklight/server.yml
index 6ef0e82..8d95ad3 100644
--- a/classes/cluster/virtual-mcp11-k8s-contrail/stacklight/server.yml
+++ b/classes/cluster/virtual-mcp11-k8s-contrail/stacklight/server.yml
@@ -13,6 +13,7 @@
 - system.glusterfs.server.volume.prometheus
 - system.salt.minion.cert.prometheus_server
 - system.keepalived.cluster.instance.prometheus_server_vip
+- system.prometheus.server.alertmanager.dns
 - system.prometheus.server.target.etcd
 - system.prometheus.server.target.kubernetes
 - system.prometheus.server.target.dns