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Welcome to this walkthrough on setting up Apache Kafka in KRaft mode (no ZooKeeper) on CentOS. By the end, you’ll have a single-node Kafka cluster running with the built-in Raft quorum protocol.

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Prerequisites

  • CentOS 7 or later
  • Java 11+ installed (java -version)
  • Minimum 4 GB RAM and 2 CPU cores

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Download and Extract Apache Kafka

  1. Download Kafka 3.0.0 (Scala 2.13): 
    wget https://archive.apache.org/dist/kafka/3.0.0/kafka_2.13-3.0.0.tgz
  2. Extract the archive: 
    tar -xvf kafka_2.13-3.0.0.tgz
  3. Enter the Kafka directory: 
    cd kafka_2.13-3.0.0

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Explore the Directory Structure

List the top-level folders: 
ls -l
# bin  config  libs  site-docs
Dive into the config directory and view the KRaft config files: 
cd config
ls kraft
# controller.properties  server.properties
FilePurposeDefault Path
controller.propertiesConfiguration for the Raft controller (metadata)config/kraft/controller.properties
server.propertiesBroker settings + Raft metadata directoriesconfig/kraft/server.properties
You can customize log directories, ports, and listeners in these files before formatting storage.

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Format Local Storage for KRaft

Before starting Kafka, initialize local storage and bind it to a cluster ID.
  1. Generate a UUID for your cluster: 
    bin/kafka-storage.sh random-uuid
# Example output: fRbs-vkR9Uevh5Cwlwk
  2. Format the storage with the generated UUID: 
    bin/kafka-storage.sh format \
  -t fRbs-vkR9Uevh5Cwlwk \
  -c config/kraft/server.properties
    This embeds the cluster ID into the log directories (default: /tmp/kraft-logs).
Reformatting storage erases existing logs. Only run this command once on a fresh directory.

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Start Kafka in KRaft Mode

Launch the combined broker and controller process: 
bin/kafka-server-start.sh config/kraft/server.properties
Look for logs like: 
2025-04-17 14:18:03,196 INFO [RaftManager nodeId=1] Completed transition to Leader(localId=1, epoch=1)
2025-04-17 14:18:06,711 INFO Kafka server 3.0.0-0 started (kafka.server.KafkaRaftServer)
If you see KafkaRaftServer and no zookeeper.connect references, your cluster is running in KRaft mode.

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Verifying KRaft vs. ZooKeeper

  • KRaft mode logs mention RaftManager and KafkaRaftServer.
  • There are no ZooKeeper processes or settings.
  • The controller and broker run within a single JVM.

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Next Steps

  1. Create topics: 
    bin/kafka-topics.sh --create --topic test --bootstrap-server localhost:9092 --partitions 3 --replication-factor 1
  2. Produce and consume messages: 
    bin/kafka-console-producer.sh --topic test --bootstrap-server localhost:9092
bin/kafka-console-consumer.sh --topic test --bootstrap-server localhost:9092 --from-beginning
  3. Scale to multi-node KRaft clusters by repeating storage formatting with unique IDs and updating controller.quorum.voters.

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