3 posts tagged with "KRaft"

Yes — running Kafka without ZooKeeper is not just possible, it is now the only supported way forward. Kafka has run without ZooKeeper in production since version 3.3, ZooKeeper mode was deprecated in 3.5, and Kafka 4.0 removed it entirely. A 4.x broker will not even start against a ZooKeeper ensemble.

The question arrives in many forms: is ZooKeeper still required? Is it removed? Can I run Kafka without it today? The answer depends entirely on which Kafka version and platform you are on. This post gives the version-by-version answer, lists what still requires ZooKeeper, and shows how to start a cluster with no ZooKeeper anywhere.

So what is ZooKeeper in Kafka, exactly? ZooKeeper is the external coordination service that ZooKeeper-mode Kafka clusters use to elect the controller, track which brokers are alive, and store cluster metadata — topics, partition assignments, configs, and ACLs. It is also on its way out: Apache Kafka deprecated ZooKeeper mode in 3.5 and removed it entirely in 4.0, replacing it with KRaft, a metadata quorum built into Kafka itself.

You still see ZooKeeper everywhere. Old tutorials start it before the broker, inherited clusters have zookeeper.connect in every properties file, and interview questions treat it as core Kafka knowledge. This post explains what the service actually does, what it never stored, what breaks when it fails, and why the whole layer is being retired.

How you run a ZooKeeper to KRaft migration depends entirely on where your Kafka lives. Self-managed clusters migrate in place with a rolling, dual-write procedure (KIP-866) through the Kafka 3.9 bridge release. Strimzi drives that same procedure on Kubernetes with a single annotation, Confluent Platform runs it on versions 7.6.1 through 7.9 before the KRaft-only 8.0 upgrade — and AWS MSK has no in-place path at all, which turns the migration into a cluster move.

The deadline is upstream and fixed: ZooKeeper mode was deprecated in Apache Kafka 3.5 and removed in 4.0. If you are still weighing the two modes, the KRaft vs ZooKeeper comparison settles that question. This guide assumes the decision is made and covers the part that actually carries risk: moving every cluster you have, on each platform, without losing metadata, offsets, or your rollback option.