Add option to choose Kafka client in Docker

- Add docker option to choose confluent-kafka or legacy kafka.
- Set confluent-kafka as default.

Change-Id: I5464f999ace16d9093e90e7ce7204406131bdf15
Story: 2006436
Task: 41145

docker/Dockerfile

@@ -18,6 +18,7 @@ FROM monasca/base:$BASE_TAG
 ENV \
     KAFKA_URI=kafka:9092 \
     KAFKA_WAIT_FOR_TOPICS=alarm-state-transitions,metrics \
+    KAFKA_LEGACY_CLIENT_ENABLED=false \
     MONASCA_CONTAINER_API_PORT=8070 \
     DATABASE_BACKEND=influxdb \
     INFLUX_HOST=influxdb \

docker/README.rst

@@ -25,6 +25,7 @@ Environment variables
 Variable                       Default                                                                 Description
 ============================== ======================================================================= ==========================================
 KAFKA_URI                      kafka:9092                                                              URI to Apache Kafka (distributed streaming platform)
+KAFKA_LEGACY_CLIENT_ENABLED    false                                                                   Enable legacy Kafka client
 MONASCA_CONTAINER_API_PORT     8070                                                                    The port from the metric pipeline endpoint
 DATABASE_BACKEND               influxdb                                                                Select for backend database
 INFLUX_HOST                    influxdb                                                                The host for influxdb

docker/monasca-api.conf.j2

@@ -498,6 +498,13 @@ wait_time = 1
 # effect on stability and/or performance.
 #auto_commit = false
 
+#
+# Enable legacy Kafka client. When set old version of
+# kafka-python library is used. Message format version
+# for the brokers should be set to 0.9.0.0 to avoid
+# performance issues until all consumers are upgraded.
+legacy_kafka_client_enabled = {{ KAFKA_LEGACY_CLIENT_ENABLED | default(false) }}
+
 
 [keystone_authtoken]