Spring Boot Reactive Kafka Demo

A reactive Spring Boot application demonstrating Kafka message publishing and consuming using WebFlux.

Features

• Reactive Kafka Producer and Consumer
• WebFlux endpoints
• Message validation
• Error handling
• Server-Sent Events (SSE) for real-time message consumption

Prerequisites

• Java 17+
• Docker
• Maven

Setup

1. Start Kafka using Docker:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

brew install --cask docker

Either click the Docker Desktop icon in Applications

open /Applications/Docker.app

docker --version docker ps

User the cocker-compose.yml file to start Kafka and Zookeeper

Start Kafka and Zookeeper using docker-compose

docker-compose up -d

Check running containers

docker ps

Check Kafka logs

docker logs

debugging kafka issues docker exec -it /bin/bash kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic demo-topic --from-beginning

Testing the application

mvn spring-boot:run

Check running containers

docker ps

Check Kafka logs

docker logs

Publishing a message to the Kafka topic

curl -X POST http://localhost:8080/api/kafka/publish -H "Content-Type: application/json" -d '{"message": "Hello, Kafka!"}'

Consuming messages from the Kafka topic

curl http://localhost:8080/api/kafka/consume