Current state: "Draft"
Discussion thread: here
JIRA: KAFKA-5639
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
The DescribeGroups
protocol v1 currently returns this information for each consumer group:
error_code
group_id
state
protocol_type
protocol
members
(only a member summary is returned per member that misses some useful member info too)Additional info exist or can be derived in a GroupMetadata
object on the server side, some of which could be useful if exposed via the DescribeGroups
protocol. Here are some examples:
generationId
leaderId
supportedProtocols
per memberEnhancing the protocol with some of this additional info means improving the existing tools that make use of it. For example, using this additional info, the consumer group command's --describe
output will provide more information about each consumer group to help with understanding the group behavior, its monitoring, troubleshooting, etc.
This is the latest version (v1) of DescribeGroups
protocol:
DescribeGroups Request (Version: 1) => [group_ids] group_ids => STRING DescribeGroups Response (Version: 1) => throttle_time_ms [groups] throttle_time_ms => INT32 groups => error_code group_id state protocol_type protocol [members] error_code => INT16 group_id => STRING state => STRING protocol_type => STRING protocol => STRING members => member_id client_id client_host member_metadata member_assignment member_id => STRING client_id => STRING client_host => STRING member_metadata => BYTES member_assignment => BYTES |
The suggestion is to enhance the protocol to version 2 and add some of these currently missing information (*
indicates suggested fields to be added to the protocol):
DescribeGroups Request (Version: 2) => [group_ids] group_ids => STRING DescribeGroups Response (Version: 2) => throttle_time_ms [groups] throttle_time_ms => INT32 groups => error_code group_id state protocol_type protocol generation_id leader_id new_member_added received_consumer_offset_commits received_transactional_offset_commits [members] error_code => INT16 group_id => STRING state => STRING protocol_type => STRING protocol => STRING * generation_id => INT32 * leader_id => STRING members => member_id client_id client_host member_metadata member_assignment member_subscription [member_protocols] member_id => STRING client_id => STRING client_host => STRING member_metadata => BYTES member_assignment => BYTES * member_subscription => BYTE * member_protocols => STRING |
The proposal is to
DescribeGroups
protocol to include additional information about the consumer group and also each group member for the API clients.--state
option to also include a GENERATION-ID
and LEADER-ID
column.ASSIGNMENT-STRATEGY
value for --members
option.SUBSCRIPTION
value for --members --verbose
option.Since this KIP follows KIP-175, the output for sub-options --members
and --state
that are introduced in that KIP will be modified to also include the newly added fields. Therefore, clients who rely on the output for those sub-options may need to be adjusted. It also helps the consumer group --describe
command to fill some of the newly added columns introduced by KIP-175 (i.e. ASSIGNMENT-STRATEGY
for --members
options, and SUBSCRIPTION
for --members --verbose
option).