KRaft Mode - The only mode in Kafka 4.x

🆕 What is KRaft?

KRaft (Kafka Raft) is the Apache Kafka architecture that eliminates the Zookeeper dependency. It is the default and only mode supported by Kafka 4.x — ZooKeeper was removed in Kafka 4.0.

✅ KRaft Advantages

• 🚀 Faster startup - Fewer components to initialize
• 📦 Less complexity - One less component to manage
• 🔧 Simplified configuration - No Zookeeper to configure
• ⚡ Better performance - Metadata managed directly by Kafka

🚀 How to Use in Kafka Metamorphosis

Complete KRaft Mode (Kafka + UI)

;; Complete setup with KRaft + Kafka UI
(dev/kafka-setup-kraft!)

;; Or with specific topics
(dev/kafka-setup-kraft! ["orders" "payments" "notifications"])

;; Just start without creating topics
(dev/kafka-up-kraft!)

Simple KRaft Mode (Recommended for Tests)

;; Minimalist setup - super fast, no UI
(dev/kafka-setup-simple!)

;; Just start Kafka without UI
(dev/kafka-up-simple!)

🏗️ Architectures

KRaft Mode

┌─────────────┐    ┌─────────────┐
│    Kafka    │    │  Kafka UI   │
│   :9092     │◄──►│   :8080     │
│ (+ metadata)│    └─────────────┘
└─────────────┘

Simple KRaft

┌─────────────┐
│    Kafka    │
│   :9092     │
│ (+ metadata)│
└─────────────┘

⚙️ Generated Configurations

Complete KRaft (kraft-docker-compose)

services:
  kafka:
    image: apache/kafka:4.3.0
    environment:
      KAFKA_NODE_ID: 1
      KAFKA_PROCESS_ROLES: "broker,controller"
      KAFKA_CONTROLLER_QUORUM_VOTERS: "1@localhost:29093"
      # Single-node replication overrides
      KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1
      KAFKA_TRANSACTION_STATE_LOG_REPLICATION_FACTOR: 1
      KAFKA_TRANSACTION_STATE_LOG_MIN_ISR: 1
      KAFKA_SHARE_COORDINATOR_STATE_TOPIC_REPLICATION_FACTOR: 1
      KAFKA_SHARE_COORDINATOR_STATE_TOPIC_MIN_ISR: 1

  kafka-ui:
    # Web interface at localhost:8080

Simple KRaft (kraft-simple-docker-compose)

services:
  kafka:
    image: apache/kafka:4.3.0
    ports:
      - "9092:9092"
    environment:
      KAFKA_PROCESS_ROLES: "broker,controller"
      # … minimal single-node configuration

🛠️ Recommended Workflow

For Daily Development

;; 1. Quick setup for development
(dev/kafka-setup-kraft!)

;; 2. Use normally
(dev/send-test-messages "my-topic" 5)
(dev/read-test-messages "my-topic")

;; 3. Open UI in browser: http://localhost:8080

;; 4. Stop when finished
(dev/kafka-dev-teardown!)

For Quick Tests

;; 1. Minimalist setup (no UI)
(dev/kafka-setup-simple!)

;; 2. Test quickly
(dev/setup-dev-topic "test")
(dev/send-test-messages "test" 3)

;; 3. Stop
(dev/kafka-dev-teardown!)

🔧 KRaft Troubleshooting

Problem: Kafka won't start

;; View specific logs
(dev/kafka-docker-logs! "kafka")

;; Check if ports are free
;; 9092 (Kafka), 29093 (Controller)

Problem: Can't connect

;; Wait for complete initialization
(dev/wait-for-kafka 60)

;; Check status
(dev/kafka-docker-status)

Complete Reset

;; Stop and clean everything
(dev/kafka-dev-teardown! true)

;; Recreate from scratch
(dev/kafka-setup-kraft!)

🎯 Recommendations

Use KRaft When:

• ✅ Local development
• ✅ Automated tests
• ✅ New projects
• ✅ Any project targeting Kafka 4.x (mandatory)

🪲 Migration from ZooKeeper

If you used kafka-setup-zookeeper! in older versions, switch to KRaft — application code stays the same:

;; Previously (Kafka 3.x)
;; (dev/kafka-setup-zookeeper!)

;; Now (Kafka 4.x — KRaft only)
(dev/kafka-setup-kraft!)

Kafka's metamorphosis eliminates Zookeeper complexity! 🪲➡️🦋