Status

Current state: Under Discussion Adopted

Discussion thread: here

JIRA:

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

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1. The output of --describe will change to return one row per topic partition in the group. This means that group members with no assigned partition will not be present in the default output.
2. A new switch --members will be introduced, that can only be provided along with --describe, to return a list of all active members of the group. For each member the number of assigned topic partitions (without any offset information) and the assignment strategy used by the member are also returned. Additional information (such as member subscription and assignment) can also be provided with a --members --verbose option.
3. A new switch --A new switch --offsets will be introduced, that can only be provided along with --describe, that returns the same default output of --describe. I.e., this will be the default switch that can be additionally used with --describe.
4. A new switch --state will be introduced, that can only be provided along with --describe, to return group-level status information that is returned from the DescribeGroups API call.

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Note that consumers without any assigned partitions will no longer appear in the listing.

--describe --members and --describe --members --verbose

A new option --members is introduced that is allowed with --describe only and returns info about active members of the group along with their assigned topic partitions:

$ bin/kafka-consumer-groups.sh --bootstrap-server localhost:9092 --describe --group my-group --members
Note: This will only show information about consumers that use the Java consumer API (non-ZooKeeper-based consumers).
CONSUMER-ID                                       HOST                           CLIENT-ID              #PARTITIONS     ASSIGNMENT-STRATEGY
consumer1-81fe8a2a-0b29-4964-a1d4-4741582132bb    /127.0.0.1                     consumer1              2               range
consumer2-db6f12f2-e1de-4bb7-93ec-6170fefa8830    /127.0.0.1                     consumer2              1               range, round-robin
consumer7-c1d056fa-eabc-42ed-b557-c848f747ec49    /127.0.0.1                     consumer7              1               range

There is an additional --verbose switch that can be used along with this option to include additional details about each group member:

$ bin/kafka-consumer-groups.sh --bootstrap-server localhost:9092 --describe --group my-group --members --verbose
Note: This will only show information about consumers that use the Java consumer API (non-ZooKeeper-based consumers).
CONSUMER-ID                                       HOST                           CLIENT-ID              #PARTITIONS     ASSIGNMENT-STRATEGY     SUBSCRIPTION        ASSIGNMENT
consumer1-81fe8a2a-0b29-4964-a1d4-4741582132bb    /127.0.0.1                     consumer1              2               range                   my-topic            my-topic(0,1)
consumer2-db6f12f2-e1de-4bb7-93ec-6170fefa8830    /127.0.0.1                     consumer2              1               range, round-robin      my-topic            my-topicmy-topic(2)
consumer7-c1d056fa-eabc-42ed-b557-c848f747ec49    /127.0.0.1                     consumer7              1               range                   my-second-topic     my-second-topic(0)

–describe --offsets

The new --offsets option, that is allowed with --describe only, produces the same result as the --describe option itself. In other words, --offsets is the default sub-option of --describe:

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The --state option, that can also be used with --describe only, reports the group level information that comes back in the response of DescribeGroups API call along with the coordinator id of the group:

$ bin/kafka-consumer-groups.sh --bootstrap-server localhost:9092 --describe --group my-group --state
Note: This will only show information about consumers that use the Java consumer API (non-ZooKeeper-based consumers).
COORDINATOR (ID)       ASSIGNMENT-STRATEGY     STATE          #MEMBERS
localhost:9092 (0)     range                   Stable         3 

In the above outputs, the width of the following columns will be dynamically determined (as opposed to the fixed widths that have been applied so far):

• TOPIC
• CONSUMER-ID
• HOST
• CLIENT-ID
• COORDINATOR (ID)

Compatibility, Deprecation, and Migration Plan

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