KAFKA-19740: Deprecate group.coordinator.rebalance.protocols config (KIP-1237) by mingyen066 · Pull Request #21522 · apache/kafka

mingyen066 · 2026-02-20T10:01:30Z

Deprecate the group.coordinator.rebalance.protocols configuration
for removal in Kafka 5.0.
Log a deprecation warning when users disable any default protocol
(classic, consumer, streams), advising them to remove the configuration
Guard warnings with doLog to avoid duplicate output during startup
Clean up redundant group.coordinator.rebalance.protocols settings in
test files — "classic,consumer,streams" is already the default, and
share is a no-op (controlled by share.version feature)

Test result:

# group.coordinator.rebalance.protocols=classic,consumer,streams
WARN The config `group.coordinator.rebalance.protocols` is deprecated
and will be removed in Kafka 5.0. Please remove the configuration to
prepare for the upgrade. (kafka.server.KafkaConfig)

# =classic,consumer
WARN The config `group.coordinator.rebalance.protocols` is deprecated
and will be removed in Kafka 5.0. The following protocol(s) are
currently disabled: streams. In Kafka 5.0, all protocols will always be
enabled and controlled solely by feature versions (group.version,
streams.version, share.version) via kafka-features.sh. Please remove the
configuration, which will restore all protocols to the default enabled
state, to prepare for the upgrade. (kafka.server.KafkaConfig)

# =classic,streams
WARN The config `group.coordinator.rebalance.protocols` is deprecated
and will be removed in Kafka 5.0. The following protocol(s) are
currently disabled: consumer. In Kafka 5.0, all protocols will always be
enabled and controlled solely by feature versions (group.version,
streams.version, share.version) via kafka-features.sh. Please remove the
configuration, which will restore all protocols to the default enabled
state, to prepare for the upgrade. (kafka.server.KafkaConfig)

# =classic
WARN The config `group.coordinator.rebalance.protocols` is deprecated
and will be removed in Kafka 5.0. The following protocol(s) are
currently disabled: consumer, streams. In Kafka 5.0, all protocols will
always be enabled and controlled solely by feature versions
(group.version, streams.version, share.version) via kafka-features.sh.
Please remove the configuration, which will restore all protocols to the
default enabled state, to prepare for the upgrade.
(kafka.server.KafkaConfig)

# =classic,consumer,streams,share
WARN 'share' in `group.coordinator.rebalance.protocols` is deprecated.
Share groups are controlled by the 'share.version' feature. This config
will be removed in Kafka 5.0. (kafka.server.KafkaConfig)
WARN The config `group.coordinator.rebalance.protocols` is deprecated
and will be removed in Kafka 5.0. Please remove the configuration to
prepare for the upgrade. (kafka.server.KafkaConfig)

# =classic,consumer,share
WARN 'share' in `group.coordinator.rebalance.protocols` is deprecated.
Share groups are controlled by the 'share.version' feature. This config
will be removed in Kafka 5.0. (kafka.server.KafkaConfig)
WARN The config `group.coordinator.rebalance.protocols` is deprecated
and will be removed in Kafka 5.0. The following protocol(s) are
currently disabled: streams. In Kafka 5.0, all protocols will always be
enabled and controlled solely by feature versions (group.version,
streams.version, share.version) via kafka-features.sh. Please remove the
configuration, which will restore all protocols to the default enabled
state, to prepare for the upgrade. (kafka.server.KafkaConfig)

# =consumer
ERROR Exiting Kafka due to fatal exception (kafka.Kafka$)
org.apache.kafka.common.config.ConfigException: Disabling the 'classic'
protocol is not supported.

Reviewers: Sean Quah squah@confluent.io, Chia-Ping Tsai
chia7712@gmail.com

…KIP-1237) Mark the group.coordinator.rebalance.protocols configuration as deprecated for removal in Kafka 5.0. When users set a value that disables any default protocol, a warning is logged advising them to restore the default or remove the configuration. The share protocol no-op warning is also preserved.

…ls deprecation

dajac · 2026-02-22T01:59:47Z

cc @squah-confluent

chia7712 · 2026-02-22T12:33:15Z

> Task :clients:clients-integration-tests:compileTestJava
/home/chia7712/project/kafka/clients/clients-integration-tests/src/test/java/org/apache/kafka/clients/consumer/ShareConsumerRackAwareTest.java:52: warning: [removal] GROUP_COORDINATOR_REBALANCE_PROTOCOLS_CONFIG in GroupCoordinatorConfig has been deprecated and marked for removal
            @ClusterConfigProperty(key = GroupCoordinatorConfig.GROUP_COORDINATOR_REBALANCE_PROTOCOLS_CONFIG, value = "classic, share"),
                                                               ^
1 warning

> Task :tools:compileTestJava
/home/chia7712/project/kafka/tools/src/test/java/org/apache/kafka/tools/GroupsCommandTest.java:469: warning: [removal] GROUP_COORDINATOR_REBALANCE_PROTOCOLS_CONFIG in GroupCoordinatorConfig has been deprecated and marked for removal
            @ClusterConfigProperty(key = GroupCoordinatorConfig.GROUP_COORDINATOR_REBALANCE_PROTOCOLS_CONFIG, value = "classic,consumer,streams"),
                                                               ^
/home/chia7712/project/kafka/tools/src/test/java/org/apache/kafka/tools/streams/DescribeStreamsGroupTest.java:80: warning: [removal] GROUP_COORDINATOR_REBALANCE_PROTOCOLS_CONFIG in GroupCoordinatorConfig has been deprecated and marked for removal
        props.setProperty(GroupCoordinatorConfig.GROUP_COORDINATOR_REBALANCE_PROTOCOLS_CONFIG, "classic,consumer,streams");
                                                ^
/home/chia7712/project/kafka/tools/src/test/java/org/apache/kafka/tools/streams/ListStreamsGroupTest.java:75: warning: [removal] GROUP_COORDINATOR_REBALANCE_PROTOCOLS_CONFIG in GroupCoordinatorConfig has been deprecated and marked for removal
        props.setProperty(GroupCoordinatorConfig.GROUP_COORDINATOR_REBALANCE_PROTOCOLS_CONFIG, "classic,consumer,streams");
                                                ^
3 warnings

@mingyen066 please fix the build warnings

…OR_REBALANCE_PROTOCOLS_CONFIG

…in Kafka 5.0

squah-confluent

Thanks for the patch!

group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupCoordinatorConfig.java

tools/src/test/java/org/apache/kafka/tools/streams/DescribeStreamsGroupTest.java

docs/getting-started/upgrade.md

…onfig

chia7712 · 2026-02-26T14:41:40Z

@mingyen066 please fix the conflicts

…onfig

tools/src/test/java/org/apache/kafka/tools/streams/ListStreamsGroupTest.java

tools/src/test/java/org/apache/kafka/tools/streams/DescribeStreamsGroupTest.java

…treamsGroupTest

chia7712 · 2026-03-05T14:17:56Z

@mingyen066 please cleanup the following files as well

kafka/clients/clients-integration-tests/src/test/java/org/apache/kafka/clients/consumer/ShareConsumerTest.java

Line 2365 in 12eca09

    
           @ClusterConfigProperty(key = "group.coordinator.rebalance.protocols", value = "classic,consumer,share"),

kafka/core/src/test/scala/unit/kafka/server/StreamsGroupHeartbeatRequestTest.scala

Line 38 in 12eca09

    
           new ClusterConfigProperty(key = "group.coordinator.rebalance.protocols", value = "classic,consumer,streams"),

...ration-tests/src/test/java/org/apache/kafka/clients/consumer/ShareConsumerRackAwareTest.java

chia7712 · 2026-03-05T14:22:02Z

testAsyncConsumerWithConsumerProtocolDisabled should probably use group.version instead of group.coordinator.rebalance.protocols, but we can handle that in a follow-up

…st files

core/src/main/scala/kafka/server/KafkaConfig.scala

…ferentiate deprecation warnings

…essage

mingyen066 · 2026-03-09T05:04:14Z

Sorry for the accidental force push, no change, just to re-trigger CI.

tools/src/test/java/org/apache/kafka/tools/GroupsCommandTest.java

chia7712 · 2026-03-10T08:22:59Z

Ugh, looks like there's still one test using classic,consumer,streams

kafka/core/src/test/scala/unit/kafka/server/StreamsGroupDescribeRequestTest.scala

Line 73 in 8f77ee6

    
           new ClusterConfigProperty(key = GroupCoordinatorConfig.GROUP_COORDINATOR_REBALANCE_PROTOCOLS_CONFIG, value = "classic,consumer,streams"),

we'll file a minor patch

m1a2st · 2026-03-10T14:02:59Z

The fix patch #21699

#21699) Cleanup test which using `classic,consumer,streams`, see comment #21522 (comment) Reviewers: TengYao Chi <frankvicky@apache.org>, Lan Ding <isDing_L@163.com>

github-actions bot added triage PRs from the community core Kafka Broker group-coordinator small Small PRs labels Feb 20, 2026

KAFKA-19740: Add upgrade note for group.coordinator.rebalance.protoco…

69e4474

…ls deprecation

mingyen066 added 2 commits February 22, 2026 22:03

KAFKA-19740: Suppress removal warnings for deprecated GROUP_COORDINAT…

84faa1c

…OR_REBALANCE_PROTOCOLS_CONFIG

KAFKA-19740: Clarify share warning message to mention config removal …

ee82ce3

…in Kafka 5.0

github-actions bot added tools clients labels Feb 22, 2026

squah-confluent reviewed Feb 22, 2026

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Merge branch 'trunk' into KAFKA-19740-deprecate-rebalance-protocols-c…

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…onfig

Merge branch 'trunk' into KAFKA-19740-deprecate-rebalance-protocols-c…

02b1e9f

…onfig

chia7712 reviewed Mar 2, 2026

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tools/src/test/java/org/apache/kafka/tools/streams/ListStreamsGroupTest.java Outdated Show resolved Hide resolved

tools/src/test/java/org/apache/kafka/tools/streams/DescribeStreamsGroupTest.java Outdated Show resolved Hide resolved

Remove redundant default config in DescribeStreamsGroupTest and ListS…

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…treamsGroupTest

chia7712 reviewed Mar 5, 2026

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...ration-tests/src/test/java/org/apache/kafka/clients/consumer/ShareConsumerRackAwareTest.java Outdated Show resolved Hide resolved

Remove redundant group.coordinator.rebalance.protocols settings in te…

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…st files

chia7712 reviewed Mar 6, 2026

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core/src/main/scala/kafka/server/KafkaConfig.scala Show resolved Hide resolved

github-actions bot removed the small Small PRs label Mar 6, 2026

Use originals() to detect explicit rebalance protocols config and dif…

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…ferentiate deprecation warnings

mingyen066 force-pushed the KAFKA-19740-deprecate-rebalance-protocols-config branch from 9539bc2 to 13397fd Compare March 9, 2026 03:58

github-actions bot added the small Small PRs label Mar 9, 2026

Use consistent backtick formatting for config name in share warning m…

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chia7712 reviewed Mar 9, 2026

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Remove redundant default config in GroupsCommandTest

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chia7712 approved these changes Mar 10, 2026

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chia7712 merged commit 5e33fe7 into apache:trunk Mar 10, 2026
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m1a2st mentioned this pull request Mar 10, 2026

MINOR: Followup Deprecate group.coordinator.rebalance.protocols config #21699

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