Apache Kafka Notes

22/1/2023 16:7 - Asia/Calcutta

Kafka docker-compose

 

Docker Compose is a tool for defining and running multi-container Docker applications. It allows you to define the services that make up your application in a single YAML file and start and stop them with a single command.

To set up a Kafka cluster using Docker Compose, you will need to create a docker-compose.yml file that defines the services for your application. Here is an example of a simple docker-compose.yml file that starts a single Kafka broker:

 

version: '3'
services:
  kafka:
    image: confluentinc/cp-kafka:latest
    ports:
      - "9092:9092"
    environment:
      KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://kafka:9092
      KAFKA_ZOOKEEPER_CONNECT: zookeeper:2181
    depends_on:
      - zookeeper
  zookeeper:
    image: confluentinc/cp-zookeeper:latest
    ports:
      - "2181:2181"

 

This example uses the Confluent Platform distribution of Kafka, which includes additional components such as Schema Registry and Kafka REST proxy. The KAFKA_ADVERTISED_LISTENERS environment variable is used to specify the hostname and port that the broker should advertise to clients. The KAFKA_ZOOKEEPER_CONNECT environment variable is used to specify the hostname and port of the Zookeeper service.

Once you have created the docker-compose.yml file, you can start the cluster by running docker-compose up a command. This will start with the Zookeeper and Kafka broker services defined in the file.

You can use this method to launch multiple brokers, and then use the advertised listener of each broker in the others, to define a cluster.

It's worth noting that using this method you can have a Kafka cluster up and running in a matter of minutes, but it's not recommended for production use, as it's not designed to handle the complexity and requirements of a real production environment.

 

KafkaJs

Kafkajs is a client library for working with Apache Kafka in Node.js. It is a modern, high-performance, and feature-rich library that allows you to easily interact with a Kafka cluster from your Node.js applications. It provides an easy-to-use and consistent API for producing, consuming, and managing data in a Kafka cluster.

Kafkajs allows you to create Kafka consumers, producers, and topic management operations in an easy and efficient way, it abstracts away the complexity of the underlying Kafka protocol and provides a simple, high-level API. It also provides features like automatic offset management, consumer groups, and error handling.

The library supports all the standard Kafka protocol features and also provides some additional features such as metadata management, transaction support, and support for compression.

Kafkajs is a great option for building real-time data pipelines and streaming applications in Node.js. It is actively maintained and has a growing community of users and contributors.

It's worth noting that since Kafka is a distributed system, it's important to test your application with a real Kafka cluster, and not rely solely on local development, even when using Kafkajs.

 

Debzium Kafka

Debezium is an open-source distributed platform for change data capture (CDC) that captures row-level changes in a database and streams them as a change event to Apache Kafka. It can be used to stream the changes from multiple databases and make them available for real-time data processing, analytics, and integration with other systems.

Debezium uses a plugin architecture that allows it to support multiple databases, including MySQL, PostgreSQL, MongoDB, and SQL Server. Each plugin is responsible for capturing changes from the corresponding database and streaming them to Kafka.

Debezium uses a combination of database-specific technologies and logical log replication to capture and stream the changes. For example, for MySQL, it uses the MySQL binary log to capture changes, and for PostgreSQL, it uses the logical replication feature to capture changes.

Once the changes are captured, they are sent to a Kafka topic, where they can be consumed by other systems for further processing and analysis. The change events are sent in a format that is compatible with Apache Kafka Connect, which makes it easy to integrate with other systems.

Debezium provides a powerful and flexible platform for real-time data integration and stream processing. It can be used to build event-driven architectures, data pipelines, and real-time analytics applications.

 

Kafka Zookeeper

Apache Zookeeper is a centralized service for maintaining configuration information, naming, and providing distributed synchronization. It is often used in combination with Apache Kafka to coordinate the distribution of data and handle failover in a Kafka cluster.

If you are getting an error that "zookeeper is not a recognized option", it could mean that the software or command you are using is not configured to work with Zookeeper. This could be because the software or command you are using is not designed to work with Zookeeper, or it could be due to a configuration issue.

It's important to check the documentation for the specific software or command you are using to see if it supports Zookeeper, and if so, how to configure it to work with Zookeeper. It could also be that the error message is related to a specific version of the software or command that you're using and not related to Zookeeper itself.

If you are using Kafka, it's important to have Zookeeper running in order to handle coordination and failover within the Kafka cluster. Without Zookeeper, the Kafka brokers won't be able to elect a leader, and the Kafka cluster will not function properly.

You can use the standalone version of Zookeeper or you can use the version embedded in Confluent Platform, which includes additional components such as Schema Registry and Kafka REST proxy.

 

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