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This is a mini-KIP proposal to allow a legacy Kafka in the 3.9.2 maintenance release to invoke an AlterConfigPolicy
in the same way when running in ZooKeeper mode and KRaft mode, thereby facilitating migration to KRaft.

Status

Current state: "Under DiscussionAdopted"

Discussion thread: here-2 and here- TBD1 

JIRA: KAFKA-19026 

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

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Also OpType.APPEND behaves inconsistently in this regard.

The behaviour shown in the ZK case makes it impossible to write a policy that fully protects topics from being left with an empty cleanup policy
(when that happens, no retention is applied and partitions can grow indefinitely).

As discussed on the dev mailing list, to avoid introducing a potentially breaking change in 3.9.2, this KIP proposes to fix the the adoption of a flag to control the policy behavior.

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Compatibility, Deprecation, and Migration Plan

• The new configuration entry will not be ported to 4.x versions where there is no ZkAdminManager component
• What impact (if any) will there be on existing users? 
  • none as the configration configuration would be false by default
• If we are changing behavior how will we phase out the older behavior?
  • not planned as Zookeper mode is phased out
• After a KRaft migration, the configuration can be removed from server.properties 
  • KRaft servers will ignore it however

Test Plan

Junit testing leveraging the @ClusterTest extension

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