Support KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR

[marhoc]

With the latest release there seems to be no reliable way to change offsets.topic.replication.factor in server.properties of the broker. Also setting the environment variable KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR as part of the container config has no effect. We would like to set the replication factor (default: 3) to 1 in our development environments to avoid having to deploy 3 brokers for each environment.

Strangely neither changing /opt/kafka/bin/server.properties.sh nor adding the setting directly to /opt/kafka/config/server.properties seems to have any effect, since after restating the broker this setting gets dropped somehow from the properties-file again.

The only workaround I found so far is modifying the invocation of kafka-server-sart.sh in /opt/kafka/bin/kafka-service.sh by adding --override offsets.topic.replication.factor=1 to it. This feels like a temporary solution only, though.

Please check if support for this environment variable can be added to the broker-container.

We are currently using Kafka 1.1.0-1.