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To mimic the tooling behavior of the old consumer group tool, this KIP proposes supporting the --delete switch for Kafka stored group offsets (new consumer) too. The behavior of --delete for the new consumer will be similar to that of the old consumer. For example, if group has active consumers the deletion will fail. In other words, a group can be deleted only when its state is Empty.

Public Interfaces

While existing APIs remain unchanged a new API DeleteGroups is introduced to remove offsets of the given group(s) from the internal offset cache.

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• 0: None
• 15: COORDINATOR_NOT_AVAILABLE
• 24: INVALID_GROUP_ID
• 30: GROUP_AUTHORIZATION_FAILED
• ??: NON_EMPTY_GROUP
• ??:GROUP_ID_NOT_FOUND

Note that the error code this KIP proposes two new error codes:

• NON_EMPTY_GROUP

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• : addresses the case where the group is not empty (i.e. group state is not Empty) and cannot be deleted.
• GROUP_ID_NOT_FOUND: addresses the case where the requested group id does not exist.

A --delete switch for the consumer group command tool (kafka-consumer-groups.sh) will by supported for Kafka stored group offsets (new consumer) too, which behaves similar to its old consumer counterpart. For example, if group has active consumers the deletion will fail. In other words, a group can be deleted only when its state is Empty. 

Similar to how the consumer group command line tool supports describing a single group at a time, the deletion functionality will be implemented the same way (deleting one group at a time). The protocol, however, support deleting multiple groups in one request.

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