The kafka-consumer-groups Command

It is time we add the final tool in our tool belt—the kafka-consumer-groups command, which can be an important aid in understanding and debugging Kafka Streams applications. We’ll be using this command to:

• See how many members exist in a group.

• Which partition (or partitions) each member is assigned.

• Check the offset of each partition and consumer.

• Check if the group is rebalancing.

Setting up the system

We learned about consumer groups using an example that contained:

• A topic with three partitions called payments.

• A producer writing messages to the topic.

• A consumer group called processors, which started with one consumer and ended up with three.

• Another consumer group called reports, with one member.

We’ll be using the terminal below to run the different services in the system.