This 89th edition of the Kafka Monthly Digest covers what happened in the Apache Kafka community in June 2025.
For last month’s digest, see Kafka Monthly Digest: May 2025.
Releases
There are two releases in progress:
4.1.0
The release process continued with feature freeze on June 4, and finally code freeze on June 25. We are now in the stabilization period and the first release candidate is expected in early July. You can find the release plan in the wiki.
4.0.1
On June 26, Christo Lolov volunteered to run this bugfix release. It's expected to release in August. The release plan is available in the wiki.
Kafka Improvement Proposals
Last month, the community submitted 4 KIPs (KIP-1186 to KIP-1189). I'll highlight a few of them:
- KIP-1186: Update AddRaftVoterRequest RPC to support auto-join: Kafka 3.9.0 introduced dynamic KRaft quorums via KIP-853. One feature of that KIP was the ability for controllers to automatically join a cluster to simplify scaling or recovery operations. However it turned out to be complicated and the original proposal could lead to availability issues. This KIP aims at fixing the design and finally implementing this feature.
- KIP-1187: Support to retrieve remote log size via DescribeLogDirs RPC: The
DescribeLogDirsAPI allows retrieving information about the log directories of the brokers such as their path, the topics and partitions they host and their size on disk. This KIP proposes extending this API to handle topics using tiered storage, so users could also retrieve the size used by each partition on the remote storage system.
- KIP-1188: New ConnectorClientConfigOverridePolicy with allowlist of configurations: By default Kafka Connect allows connectors to override all the configurations of the internal Kafka client that Connect workers use. This is useful so users can finely tune clients for the needs of their Connect pipelines. However this gives a lot of power to users and has led to multiple CVEs affecting Connect in the past couple of years. This KIP proposes a new built-in override policy that would let Connect administrators explicitly list which configurations they want to allow connectors to override.
Community Releases
- kroxylicious 0.13.0: Kroxylicious is an open source network proxy that understands the Apache Kafka protocol. The biggest feature of this release is the introduction of a Kubernetes operator to simplify deploying and managing the proxy in Kubernetes environments. This release also brings improvements to metrics to ease monitoring.
Blogs
I selected some interesting blog articles that were published last month:
To learn more about Kafka, visit Red Hat Developer's Apache Kafka topic page.
