Upgrading Apache Kafka Clients Just Got Easier

This post introduces bidirectional client compatibility for Apache Kafka, enabled by KIP-35 and KIP-97. It explains how newer clients can communicate with older brokers and vice-versa, simplifying upgrades. The technical implementation relies on API versioning and the ApiVersionsRequest mechanism, where clients query brokers for supported API versions. This allows for independent client and broker upgrades, reducing downtime and operational overhead. The post also highlights the `api.version.request` configuration for source-available clients and introduces the `kafka-broker-api-versions.sh` command-line tool for inspecting broker API support.