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Zookeeper & Kafka
- Zookeeper manages brokers (keeps a list of them)
- Zookeeper helps perform leader election for partitions
- Zookeeper sends notifications to Kafka in case of changes
- e.g., new topic, broker dies, broker comes up, delete topics, etc.
- Kafka 2.x cannot work without Zookeeper
- Kafka 3.x can work without Zookeeper (KIP-500) — using Kafka Raft (KRaft) instead
- Kafka 4.x will not have Zookeeper
- Zookeeper operates with an odd number of servers (1, 3, 5, 7)
- Zookeeper has a leader (handles writes); the rest are followers (handle reads)
- With Kafka > v0.10, Zookeeper does not store consumer offsets
Zookeeper with Kafka Brokers
- Yes, Zookeeper is still used until Kafka 4.0 is released and Kafka without Zookeeper is fully production-ready
Zookeeper with Kafka Clients
- Over time, Kafka clients and CLI have been migrated to leverage brokers as the connection endpoint instead of Zookeeper
- Since Kafka 0.10, consumers store offsets in Kafka (not Zookeeper) and must not connect to Zookeeper, as it is deprecated
- Since Kafka 2.2,
kafka-topics.shreferences Kafka brokers instead of Zookeeper for topic management (creation, deletion, etc.), and the Zookeeper CLI argument is deprecated - All APIs and commands that previously used Zookeeper now use Kafka instead — making migration to Kafka without Zookeeper invisible to clients
- Zookeeper is less secure than Kafka; Zookeeper ports should only allow traffic from Kafka brokers, not from Kafka clients
- As a modern-day Kafka developer:
Never use Zookeeper as a configuration in your Kafka clients or any programs connecting to Kafka