Prometheus fixes

* Rename 'replica' to 'replicas' in docker/swarm/service/monitoring
* Add 'discovery_domain' environment for entrypoint
* Build prometheus/server/target/etcd.yml yourself
* Build prometheus/server/target/kubernetes.ym yourself
* Add prometheus/server/target/dns.yml
* Fix SSL permissions for prometheus

Change-Id: Icae085f6b0762ada58d03cde276963ec1e4bdefa
diff --git a/docker/swarm/service/monitoring/prometheus_alertmanager.yml b/docker/swarm/service/monitoring/prometheus_alertmanager.yml
index 99eb226..5d5f237 100644
--- a/docker/swarm/service/monitoring/prometheus_alertmanager.yml
+++ b/docker/swarm/service/monitoring/prometheus_alertmanager.yml
@@ -6,11 +6,12 @@
       service:
         prometheus_alertmanager:
           network: monitoring
-          replica: 2
+          replicas: 2
           environment:
             config_dir: /opt/alertmanager/config
             bind_port: ${prometheus:alertmanager:bind:port}
             bind_address: ${prometheus:alertmanager:bind:address}
+            discovery_domain: 'prometheus_alertmanager'
           restart:
             condition: any
           image: ${_param:docker_image_alertmanager}