Set maximum buffer size for Kafka producer

The change sets queue.buffering.max.messages configuration option for
Kafka producer effectively limiting the number of messages in the buffer
before sending them to Apache Kafka.

Depends-On: https://review.opendev.org/694738
Change-Id: I6ebd4e21e9d55d1ac836e92dd8bf02a678170c68
Story: 2006059
Task: 37532

monasca_api/common/messaging/kafka_publisher.py

@@ -20,7 +20,6 @@ from oslo_log import log
 from monasca_api.common.messaging import exceptions
 from monasca_api.common.messaging import publisher
 
-
 LOG = log.getLogger(__name__)
 
 
@@ -44,8 +43,10 @@ class KafkaPublisher(publisher.Publisher):
         self.partitions = cfg.CONF.kafka.partitions
         self.drop_data = cfg.CONF.kafka.drop_data
 
+        config = {'queue.buffering.max.messages':
+                  cfg.CONF.kafka.queue_buffering_max_messages}
         self._producer = client_factory.get_kafka_producer(
-            self.uri, cfg.CONF.kafka.legacy_kafka_client_enabled)
+            self.uri, cfg.CONF.kafka.legacy_kafka_client_enabled, **config)
 
     def close(self):
         pass