Support cassandra connection timeout option

Creating a cassandra connection can be limited by connection_timeout option.

Story: 2005450
Task: 30502

Change-Id: I8803e28fe8c2c11e819be44db4ef93cb19b47a1d

monasca_api/common/repositories/cassandra/metrics_repository.py

@@ -124,6 +124,7 @@ class MetricsRepository(metrics_repository.AbstractMetricsRepository):
             self.cluster = Cluster(self.conf.cassandra.contact_points,
                                    port=self.conf.cassandra.port,
                                    auth_provider=auth_provider,
+                                   connect_timeout=self.conf.cassandra.connection_timeout,
                                    load_balancing_policy=TokenAwarePolicy(
                                        DCAwareRoundRobinPolicy(
                                            local_dc=self.conf.cassandra.local_data_center))

monasca_api/conf/cassandra.py

@@ -40,6 +40,10 @@ Cassandra user for monasca-api service
     cfg.StrOpt('password', default='', secret=True,
                help='''
 Cassandra user password for monasca-api service
+'''),
+    cfg.IntOpt('connection_timeout', default=5,
+               help='''
+Cassandra timeout in seconds when creating a new connection
 '''),
     cfg.StrOpt('local_data_center', default='',
                help='''

releasenotes/notes/cassandra-connectiontimeout-option-13bc68e2fcd56580.yaml

@@ -0,0 +1,4 @@
+---
+features:
+  - |
+    Support cassandra connection timeout option which set timeout when creating a new connection.