Add Alertmanager prometheus endpoint and replace ports with variables

Change-Id: I55867b8e483e48204d6393a3542f254556262905
diff --git a/docker/swarm/service/monitoring/prometheus_pushgateway.yml b/docker/swarm/service/monitoring/prometheus_pushgateway.yml
index ad159b6..850f66e 100644
--- a/docker/swarm/service/monitoring/prometheus_pushgateway.yml
+++ b/docker/swarm/service/monitoring/prometheus_pushgateway.yml
@@ -1,3 +1,5 @@
+classes:
+- service.prometheus.pushgateway.container
 parameters:
   docker:
     client:
@@ -5,8 +7,11 @@
         prometheus_pushgateway:
           network: monitoring
           replicas: 2
+          environment:
+            bind_port: ${prometheus:pushgateway:bind:port}
+            bind_address: ${prometheus:pushgateway:bind:address}
           restart:
             condition: any
           image: ${_param:docker_image_pushgateway}
           ports:
-            - 15012:9091
+            - 15012:${prometheus:pushgateway:bind:port}