🎧 Apache Kafka 3.3 - KRaft, Kafka Core, Streams, & Connect Updates

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Apache Kafka® 3.3 is released! With over two years of development, KIP-833 marks KRaft as production ready for new AK 3.3 clusters only. On behalf of the Kafka community, Danica Fine (Senior Developer Advocate, Confluent) shares highlights of this release, with KIPs from Kafka Core, Kafka Streams, and Kafka Connect.

To reduce request overhead and simplify client-side code, KIP-709 extends the OffsetFetch API requests to accept multiple consumer group IDs. This update has three changes, including extending the wire protocol, response handling changes, and enhancing the AdminClient to use the new protocol.

Log recovery is an important process that is triggered whenever a broker starts up after an unclean shutdown. And since there is no way to know the log recovery progress other than checking if the broker log is busy, KIP-831 adds metrics for the log recovery progress with `RemainingLogsToRecover` and `RemainingSegmentsToRecover`for each recovery thread. These metrics allow the admin to monitor the progress of the log recovery.

Additionally, updates on Kafka Core also include KIP-841: Fenced replicas should not be allowed to join the ISR in KRaft. KIP-835: Monitor KRaft Controller Quorum Health. KIP-859: Add metadata log processing error-related metrics.

KIP-834 for Kafka Streams added the ability to pause and resume topologies. This feature lets you reduce rescue usage when processing is not required or modifying the logic of Kafka Streams applications, or when responding to operational issues. While KIP-820 extends the KStream process with a new processor API.

Previously, KIP-98 added support for exactly-once delivery guarantees with Kafka and its Java clients. In the AK 3.3 release, KIP-618 offers the Exactly-Once Semantics support to Confluent’s source connectors. To accomplish this, a number of new connectors and worker-based configurations have been introduced, including `exactly.once.source.support`, `transaction.boundary`, and more.

Image attribution: Apache ZooKeeper™: https://zookeeper.apache.org/ and Raft logo: https://raft.github.io/


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