In order to set this up, the `compose.yaml` for Kafka needs some additional configuration. Once you start overriding some of the defaults, you also need to specify a few other options in order for KRaft mode to work.

```yaml
services:
  kafka:
    image: apache/kafka-native
    ports:
      - "9092:9092"
    environment:
      # Configure listeners for both docker and host communication
      KAFKA_LISTENERS: CONTROLLER://localhost:9091,HOST://0.0.0.0:9092,DOCKER://0.0.0.0:9093
      KAFKA_ADVERTISED_LISTENERS: HOST://localhost:9092,DOCKER://kafka:9093
      KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: CONTROLLER:PLAINTEXT,DOCKER:PLAINTEXT,HOST:PLAINTEXT

      # Settings required for KRaft mode
      KAFKA_NODE_ID: 1
      KAFKA_PROCESS_ROLES: broker,controller
      KAFKA_CONTROLLER_LISTENER_NAMES: CONTROLLER
      KAFKA_CONTROLLER_QUORUM_VOTERS: 1@localhost:9091

      # Listener to use for broker-to-broker communication
      KAFKA_INTER_BROKER_LISTENER_NAME: DOCKER

      # Required for a single node cluster
      KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1
```

Give it a try using the steps below.

1. If you have the Node app running from the previous step, go ahead and stop it by pressing `ctrl+c` in the terminal.

2. If you have the Kafka cluster running from the previous section, go ahead and stop that container using the following command:

   ```console
   $ docker rm -f kafka
   ```

3. Start the Compose stack by running the following command at the root of the cloned project directory:

   ```console
   $ docker compose up
   ```

   After a moment, the application will be up and running.

4. In the stack is another service that can be used to publish messages. Open it by going to [http://localhost:3000](http://localhost:3000). As you type in a message and submit the form, you should see the log message of the message being received by the app.

   This helps demonstrate how a containerized approach makes it easy to add additional services to help test and troubleshoot your application.

## Adding cluster visualization

Once you start using containers in your development environment, you start to realize the ease of adding additional services that are solely focused on helping development, such as visualizers and other supporting services. Since you have Kafka running, it might be helpful to visualize what’s going on in the Kafka cluster. To do so, you can run the [Kafbat UI web application](https://github.com/kafbat/kafka-ui).

To add it to your own project (it’s already in the demo application), you only need to add the following configuration to your Compose file:

```yaml
services:
  kafka-ui:
    image: kafbat/kafka-ui:main
    ports:
      - 8080:8080
    environment:
      DYNAMIC_CONFIG_ENABLED: "true"
      KAFKA_CLUSTERS_0_NAME: local
      KAFKA_CLUSTERS_0_BOOTSTRAPSERVERS: kafka:9093
    depends_on:
      - kafka
```

Then, once the Compose stack starts, you can open your browser to [http://localhost:8080](http://localhost:8080) and navigate around to view additional details about the cluster, check on consumers, publish test messages, and more.

## Testing with Kafka

If you’re interested in learning how you can integrate Kafka easily into your integration tests, check out the [Testing Spring Boot Kafka Listener using Testcontainers guide](https://testcontainers.com/guides/testing-spring-boot-kafka-listener-using-testcontainers/). This guide will teach you how to use Testcontainers to manage the lifecycle of Kafka containers in your tests.

## Conclusion

By using Docker, you can simplify the process of developing and testing event-driven applications with Kafka. Containers simplify the process of setting up and deploying the various services you need to develop. And once they’re defined in Compose, everyone on the team can benefit from the ease of use.

In case you missed it earlier, all of the sample app code can be found at dockersamples/kafka-development-node.