[jira] [Created] (KAFKA-12498) Consumer Group is zero when MirrorMaker 2.0 is running

["Olumide Ajiboye (Jira)" <ji...@apache.org>]

Olumide Ajiboye created KAFKA-12498:
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             Summary: Consumer Group is zero when MirrorMaker 2.0 is running
                 Key: KAFKA-12498
                 URL: https://issues.apache.org/jira/browse/KAFKA-12498
             Project: Kafka
          Issue Type: Bug
          Components: consumer, replication
    Affects Versions: 2.7.0
         Environment: Kubernetes 1.19.7
Strimzi 0.21.1

            Reporter: Olumide Ajiboye


I have two Kafka clusters in Active\Passive replication using MM 2.0.
When I produce messages to a topic and try to read from it in the same cluster, the consumer group lag is already set to zero. The replica topic also has the same lag and log-end-offset.
My MM2 is using a superuser account and I am using a separate consumer-group with permission just to read and write to this topic. 
Just to elaborate further, * Write 10 messages to a topic without any active consumers but with MM2 replicating the topic to a passive Cluster.
 * Attempt to read 3 messages from the topic, this creates my consumer group and adds an active consumer. The result is no messages are read

 * Describe the consumer group, the result shows Log-End-Offset with correct number of messages, but Lag shows 0

 * Attempt to read 3 messages from passive cluster using same consumer-group. Result: no messages consumed, Lag shows 0, Log-End-Offset shows correct number of messages (i.e. same as active cluster)

 * Keep consumer running
 * Write a few more messages.
 * Consumer is now reading latest messages
 * Stop consumer
 * Keep writing new messages
 * Lag shows correct value.

In the absence of MM2, Kafka operation is as expected.



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