Add system.prometheus.server.alertmanager.dns

Change-Id: I25ecdadfa1b854053e98f553bf6acacb0c37edd9
diff --git a/classes/cluster/virtual-mcp11-contrail/stacklight/server.yml b/classes/cluster/virtual-mcp11-contrail/stacklight/server.yml
index 4f7a0bd..dfd50bb 100755
--- a/classes/cluster/virtual-mcp11-contrail/stacklight/server.yml
+++ b/classes/cluster/virtual-mcp11-contrail/stacklight/server.yml
@@ -15,6 +15,7 @@
 - system.haproxy.proxy.listen.stacklight.kibana
 - service.haproxy.proxy.single
 - system.keepalived.cluster.instance.prometheus_server_vip
+- system.prometheus.server.alertmanager.dns
 - system.prometheus.server.target.dns
 - system.docker.swarm.stack.monitoring
 - system.docker.swarm.service.dashboard.grafana_server