Скачать или смотреть How to Run KSQLDB with Kafka Server Using Docker Compose

Learn how to easily run `KSQLDB` alongside your `Kafka` server using `Docker Compose` and troubleshoot connection issues.
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This video is based on the question https://stackoverflow.com/q/78022451/ asked by the user 'Nikolaj' ( https://stackoverflow.com/u/4433236/ ) and on the answer https://stackoverflow.com/a/78022761/ provided by the user 'OneCricketeer' ( https://stackoverflow.com/u/2308683/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Running KSQLDB with Kafka Using Docker Compose

If you're diving into the world of real-time data streaming, chances are you are using Kafka along with KSQLDB for querying Kafka topics. However, setting them up, especially in a Docker environment, can sometimes lead to headaches—one common issue being KSQLDB not connecting to your Kafka server. In this post, we’ll break down how to properly configure Docker Compose to run both KSQLDB and Kafka, ensuring a smooth setup.

The Problem: Connection Issues

Many users face a frustrating scenario where KSQLDB fails to connect to the Kafka server. Let's take a brief look at a log output from a user who encountered this issue:

[[See Video to Reveal this Text or Code Snippet]]

This indicates that KSQLDB is unable to find or connect to the Kafka broker, which is likely due to misconfiguration in the Docker setup.

Solution: Docker Compose Configuration

To resolve the connectivity issue, we'll adjust the docker-compose.yaml file to set the appropriate environment variables for Kafka and KSQLDB.

Step 1: Basic Docker Compose Structure

Initially, your docker-compose.yaml might look like this:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Update Environment Variables for Kafka

A crucial step is configuring Kafka's environment variables to ensure it advertises the correct listeners. Here is the updated configuration:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of Configurations

KAFKA_LISTENERS: This variable specifies how Kafka listens for incoming connections. We've set it to listen on multiple ports for different types of operations.

KAFKA_ADVERTISED_LISTENERS: This lets Kafka tell other services how to reach it. This is especially useful for Docker containers to communicate with each other.

KSQL_BOOTSTRAP_SERVERS: Change the bootstrap server to use the Kafka listener that is accessible by KSQLDB, which is kafka:29092.

Conclusion

By implementing the updated Docker Compose configuration above, you should be able to run KSQLDB alongside your Kafka server without any connection issues. This setup ensures that both services communicate efficiently, allowing you to experiment with streams and tables seamlessly.

Happy streaming and querying! If you have any further questions or need assistance, feel free to leave a comment below.