...

Current state: Draft

Discussion thread: here

JIRA: here KAFKA-3853

Released: <Kafka Version>

Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).

Motivation

KAFKA-3853 asks for an improvement to the new-consumer option of the consumer group command. This command, when passed a consumer group that has no consumer (i.e., when the group state is Empty), currently reports an error indicating that there is no active member:

$ bin/kafka-consumer-groups.sh --new-consumer --bootstrap-server localhost:9092 --describe --group group1
Note: This will only show information about consumers that use the Java consumer API (non-ZooKeeper-based consumers).
Error: Consumer group 'group1' has no active members.

The requested improvement is returning offsets within the group (and leaving the owner column empty) instead of returning the error message above. The error message can still be printed to to stderr as a warning.

When the group is Stable (i.e. when there are active consumers in the group), the offsets associated with the group are returned as part of the info returned for each consumer in the group in terms of a ConsumerSummary record. But there is no ConsumerSummary record if there is no consumer in the group, and therefore, in that scenario a different method is required for extracting those offsetsDescribe the problems you are trying to solve.

Public Interfaces

Briefly list any new interfaces that will be introduced as part of this proposal or any existing interfaces that will be removed or changed. The purpose of this section is to concisely call out the public contract that will come along with this feature.

...