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.

Creating the payments topic

Let’s start the terminal and create a new topic called payments with three partitions:

Starting a single payment processor