How do you create a Kafka producer in Spring Boot?

Table of Contents

• Introduction
• Steps to Create a Kafka Producer in Spring Boot
  • 1. Add Kafka Dependencies to Your Spring Boot Project
    • Maven (pom.xml):
    • Gradle (build.gradle):
  • 2. Configure Kafka Properties in **application.yml** or **application.properties**
    • Example application.yml:
  • 3. Create Kafka Producer
    • Example Kafka Producer Service:
  • 4. Create a REST Controller (Optional)
    • Example REST Controller:
  • 5. Run the Application
  • 6. Verify Message in Kafka
  • 7. Additional Configuration (Optional)
• Conclusion

Introduction

Creating a Kafka producer in Spring Boot allows your application to send messages to Kafka topics. Kafka producers are used in event-driven architectures to produce and send data streams, and Spring Boot simplifies the configuration and setup process. In this guide, we’ll walk you through the steps of creating a Kafka producer in Spring Boot, from adding dependencies to configuring the producer and sending messages.

Steps to Create a Kafka Producer in Spring Boot

1. Add Kafka Dependencies to Your Spring Boot Project

First, you need to add the necessary dependencies to your pom.xml (for Maven) or build.gradle (for Gradle) file.

Maven (pom.xml):

Gradle (build.gradle):

2. Configure Kafka Properties in **application.yml** or **application.properties**

Next, configure your Kafka producer settings in the application.yml or application.properties file. This includes specifying the Kafka broker address and other settings like the producer's group ID.

Example application.yml:

• **bootstrap-servers**: Kafka broker address (can be localhost:9092 for local development).
• **key-serializer** and **value-serializer**: These define how Kafka will serialize the message's key and value. In this case, we're using StringSerializer.

3. Create Kafka Producer

Now, let's create the Kafka producer service that will send messages to Kafka. We’ll use the KafkaTemplate to handle message sending.

Example Kafka Producer Service:

In this example:

• **KafkaTemplate**: A Spring Kafka class that simplifies the process of sending messages to Kafka topics.
• The sendMessage method sends a message to the test-topic topic.

4. Create a REST Controller (Optional)

If you'd like to expose an endpoint to send messages to Kafka, you can create a REST controller. This will allow you to trigger the Kafka producer via an HTTP request.

Example REST Controller:

• **/send** endpoint: Accepts a message as a query parameter and sends it to Kafka using the KafkaProducer class.

5. Run the Application

Once your application is set up, you can run it like any other Spring Boot application. If you're using the provided REST controller, you can now trigger the Kafka producer by navigating to:

This will send the message "HelloKafka" to the test-topic Kafka topic.

6. Verify Message in Kafka

To verify that the message was sent successfully to Kafka, you can use the Kafka command line tools to check the topic messages or use a Kafka consumer to listen for messages.

For example, you can use the kafka-console-consumer command to consume messages from a topic:

This command will display messages sent to the test-topic from the beginning.

7. Additional Configuration (Optional)

In some cases, you may want to add additional configuration, such as handling retries, batch processing, or changing the serializer. You can do this through custom ProducerFactory and KafkaTemplate configurations.

For example, here is how you could customize the KafkaTemplate with a custom ProducerFactory:

Conclusion

Creating a Kafka producer in Spring Boot is a straightforward process with the help of the spring-kafka library. By configuring the KafkaTemplate, you can easily send messages to Kafka topics, enabling your application to participate in an event-driven architecture. Whether you're building real-time data pipelines or integrating microservices, Spring Boot’s Kafka integration provides a flexible and scalable solution for messaging.