Kafka

Standard Kafka consumers transport ingests data from subscribed cluster topics

Overview

This page provides an overview of configuring the Kafka consumer in Joule to ingest data from specified Kafka topics, allowing for seamless integration with data pipelines.

Joule's Kafka consumer deserialises Kafka streams into Joule StreamEvents, enabling them to be processed within the Joule environment. This deserialisation can be automated or customised with a transformer based on configuration settings.

Client library: org.apache.kafka:kafka-clients:2.7.0

Examples & DSL attributes

The example provided illustrates how to set up a consumer to process messages from the quotes topic on a specified Kafka broker (KAFKA_BROKER:9092).

It uses the StickyAssignor strategy for partition assignment and provides an example of adding the Kafka broker's symbolic name to the /etc/hosts file.

kafkaConsumer:
  name: nasdaq_quotes_stream
  cluster address: KAFKA_BROKER:9092
  consumerGroupId: nasdaq
  topics:
    - quotes
    
  properties:
    partition.assignment.strategy: org.apache.kafka.clients.consumer.StickyAssignor

Add to the /etc/hosts file the address of the Kafka host. This enables you to use the symbolic name rather than a specific IP address i.e. 127.0.0.1 KAFKA_BROKER

Attributes schema

Attribute	Description	Data Type	Required
name	Name of source stream	String
cluster address	Kafka cluster details. Maps to bootstrap.servers	http://<ip-address>:port
consumerGroupId	Consumer group to ensure an event is read only once. Maps to group.id	String
topics	Message topics to subscribe too	List of strings
pollingTimeout	This places an upper bound on the amount of time that the consumer can be idle before fetching more records. See this documentation for more information	Long Default: 250ms
deserializer	Deserialisation configuration	See Ingestion documentation
properties	Additional consumer properties to be applied to the Kafka client API. See official documentation for available properties. Default properties applied are listed below	Properties map

Ingestion deserialisation in Joule

The Kafka consumer configuration in Joule is designed to seamlessly ingest and process data from Kafka topics by deserialising streams into Joule-compatible formats.

Using Kafka consumer attributes and custom configurations, it is possible to transform messages into Joule StreamEvents that can be processed further in data pipelines.

This setup supports various deserialisation options for efficient and flexible integration with data infrastructure. Continue with this documentation to see how it is done.

Default consumer properties

enable.auto.commit=true
auto.offset.reset=latest
auto.commit.interval.ms=50
session.sendTimeout.ms=30000
key.deserializer=org.apache.kafka.common.serialization.IntegerDeserializer
value.deserializer=org.apache.kafka.common.serialization.StringDeserializer