Docker Compose + Kafka + Spring Boot

Overview

This project aims to be a reference for those just starting to work with Java and SpringBoot in which there is a need to build an inner communication between microservices through events via Kafka. To speed up the setup of the development environment, a dockercompose is provided to provision the necessary infrastructure, i.e. Kafka and Zookeeper. Be aware of the proposed infrastructure is suitable for development and not for production operation.

Prerequisites

• Maven 3+
• Java 8+
• Docker 19.03+

Preparing Environment

From the project's folder, execute:

• docker-compose up to initialize Kafka and Zookeeper
• mvn package to build the applications

Booting Applications

• Initializing the producer

$ cd producer
$ mvn spring-boot:run

Note: The producer will be accepting request at http://localhost:8080/orders

• Initializing the consumer

$ cd consumer
$ mvn spring-boot:run

Note: The consumer has no endpoint, it just connects to the Kafka to listen to the stream events.

Testing

With both consumer and producer applications up and running, let's test their integration through Kafka:

$ curl -d "{'idorder': '1234', 'customer': 'Foo Bar', 'value': 4321}" \
-H "Content-Type: application/json" \
-X POST http://127.0.0.1:8080/orders

If the above request works, we should see a log in the producer application's console that looks like the following:

2021-07-07 06:23:26.433  INFO 2336 --- [ad | producer-1] b.c.d.producer.config.KafkaConfig        : ACK from ProducerListener message: {"idorder": "12345", "customer": "Foo Bar", "value": 54321} offset:  0

and something like in the consumer application's console:

2021-07-07 06:23:26.490  INFO 3996 --- [ntainer#0-0-C-1] b.c.d.consumer.kafka.KafkaConsumer       : Order: {"idorder": "12345", "customer": "Foo Bar", "value": 54321}

Cleaning Up

After playing around, we need to clean up the mess.. So from the project's folder, do:

1. Stop the containers using the following command:
docker-compose down
2. Delete all containers using the following command:
docker rm -f $(docker ps -a -q)