Support setting statsd metric aggregation interval

This adds support for setting the statsd metrics aggregation interval
as part of Monasca setup. Setting this interval is useful for users
calculating rates from statsd metrics.

Story: 2005063
Task: 29607
Change-Id: I22f5f1700c438245fd7e98deb40d706358349b6c

agent.yaml.template

@@ -125,7 +125,7 @@ Statsd:
   monasca_statsd_port : {args.monasca_statsd_port}
 
   ## The monasca_statsd flush period.
-  # monasca_statsd_interval : 20
+  monasca_statsd_interval : {args.monasca_statsd_interval}
 
   # If you want to forward every packet received by the monasca_statsd server
   # to another statsd server, uncomment these lines.

docs/Agent.md

@@ -113,6 +113,7 @@ All parameters require a '--' before the parameter such as '--verbose'. Run `mon
 | backlog_send_rate | Integer value of how many batches of buffered measurements to send each time the forwarder flushes data | 1000 |
 | max_batch_size | Maximum batch size of measurements to write to monasca-api, 0 is no limit | 0 |
 | monasca_statsd_port | Integer value for statsd daemon port number | 8125 |
+| monasca_statsd_interval | Integer value for the statsd metric aggregation interval (seconds) | 20 |
 
 #### A note around using monasca-agent with different versions of Keystone
 

monasca_setup/main.py

@@ -428,6 +428,9 @@ def parse_arguments(parser):
     parser.add_argument('--monasca_statsd_port',
                         help="Statsd daemon port number",
                         default=8125)
+    parser.add_argument('--monasca_statsd_interval',
+                        help="Statsd metric aggregation interval (seconds)",
+                        default=20)
     parser.add_argument('--agent_service_name',
                         help="agent's systemd/sysv service name",
                         required=False,