Supporting monitoring time synchronisation with Monasca

This plugin is useful for monitoring host clock synchronisation with
an NTP reference. If the delta becomes too large, the metrics from
this plugin can be used to trigger an alarm.

Change-Id: Id1fe6d7c823f8404c19c81ccdeb8b311bcb46e47

ansible/roles/monasca/defaults/main.yml

@@ -186,6 +186,8 @@ monasca_zookeeper_servers: "{% for host in groups['zookeeper'] %}{{ hostvars[hos
 monasca_memcached_servers: "{% for host in groups['memcached'] %}{{ hostvars[host]['ansible_' + hostvars[host]['api_interface']]['ipv4']['address'] }}:{{ memcached_port }}{% if not loop.last %},{% endif %}{% endfor %}"
 monasca_elasticsearch_servers: "{% for host in groups['elasticsearch'] %}'{{ internal_protocol }}://{{ hostvars[host]['ansible_' + hostvars[host]['api_interface']]['ipv4']['address'] }}:{{ elasticsearch_port }}'{% if not loop.last %},{% endif %}{% endfor %}"
 monasca_storm_nimbus_servers: "{% for host in groups['storm-nimbus'] %}'{{ hostvars[host]['ansible_' + hostvars[host]['api_interface']]['ipv4']['address'] }}'{% if not loop.last %},{% endif %}{% endfor %}"
+# NOTE(dszumski): Only one NTP server is currently supported by the Monasca Agent plugin
+monasca_ntp_server: "{{ external_ntp_servers | first }}"
 
 # Kafka topics used by Monasca services
 monasca_metrics_topic: "metrics"

ansible/roles/monasca/templates/monasca-agent-collector/plugins/ntp.yaml

@@ -0,0 +1,5 @@
+---
+init_config: null
+instances:
+  - built_by: Ntp
+    host: "{{ monasca_ntp_server }}"