Articles

Long-form notes from the maintainers - the design decisions, migration playbooks, and engineering lessons behind running stateful actors on Apache Flink 2.x.

Latest

• Kafka record headers in Stateful Functions - closing a five-year-old gap End-to-end header support lands in KZM-3.4: trace propagation through function graphs, typed header values, Kafka-exact null semantics, per-topic opt-in - and the protocol trick that made it possible without touching the runtime's hot path. 2026-07-24

• Upgrading the Apache Flink Kubernetes Operator from 1.11 to 1.15 for Flink 2.2 Version compatibility across operator releases, the flinkVersion: v2_2 change, a conservative configuration audit, and how the upgrade was validated. 2026-06-17

• We forked Apache Stateful Functions for Flink 2.x - here's why Why the project exists, what we changed under the hood, what stayed the same for upstream users, and where this fits versus Kafka Streams, ksqlDB, and Akka. 2026-05-03