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Status

Current state: "Under Discussion" (Draft)

Discussion thread: here [Change the link from the KIP proposal email archive to your own email thread]

JIRA: here 

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

Motivation

Currently Mirrormaker uses deprecated alterConfigs API when syncing topic configurations for broker compatibility to 0.11.0. However, the deprecated alterConfigs() API replaces any existing configuration with the new configuration. Due to this, additional configurations set on a remote topic get cleared up when MirrorMaker syncs topic configurations even if the configurations are filtered.  For example this prevents running Cruise Control on the target cluster as it may set follower.replication.throttled.replicas and leader.replication.throttled.replicas.

MirrorMaker should not clear topic configurations that are filtered on the target cluster.

Public Interfaces

This KIP proposes to use incrementalAlterConfigs API instead of the deprecated alterConfigs API in MirrorMaker for syncing topic configurations. The incrementalAlterConfigs API has been used for a long time since it was introduced in Kafka 2.3.0 and addresses the shortcoming of the deprecated alterConfigs API. In order to not break the compatibility, we will introduce a new configuration to MirrorMaker connector to enable using incrementalAlterConfigs API for syncing topic configurations. This new configuration is expected to serve as a temporary measure until the next major release when incrementalAlterConfigs API is always used. 

Briefly list any new interfaces that will be introduced as part of this proposal or any existing interfaces that will be removed or changed. The purpose of this section is to concisely call out the public contract that will come along with this feature.

A public interface is any change to the following:

• Binary log format

• The network protocol and api behavior

• Any class in the public packages under clientsConfiguration, especially client configuration

  • org/apache/kafka/common/serialization

  • org/apache/kafka/common

  • org/apache/kafka/common/errors

  • org/apache/kafka/clients/producer

  • org/apache/kafka/clients/consumer (eventually, once stable)

• Monitoring

• Command line tools and arguments

• Anything else that will likely break existing users in some way when they upgrade

Proposed Changes

Describe the new thing you want to do in appropriate detail. This may be fairly extensive and have large subsections of its own. Or it may be a few sentences. Use judgement based on the scope of the change.

Compatibility, Deprecation, and Migration Plan

• What impact (if any) will there be on existing users?
• If we are changing behavior how will we phase out the older behavior?
• If we need special migration tools, describe them here.
• When will we remove the existing behavior?

Test Plan

Describe in few sentences how the KIP will be tested. We are mostly interested in system tests (since unit-tests are specific to implementation details). How will we know that the implementation works as expected? How will we know nothing broke?

Rejected Alternatives

If there are alternative ways of accomplishing the same thing, what were they? The purpose of this section is to motivate why the design is the way it is and not some other way.