Topic creation in Kafka - Commands & Configuration

Introduction

Kafka topics are like folders where messages are stored. Creating a topic lets you organize and separate different streams of data so your apps can read and write messages clearly.

When you want to separate logs from different services to keep data organized.

When you need to create a new channel for a new feature in your app to send messages.

When you want to control how many copies of data are kept for safety.

When you want to set how many parts a topic has to allow multiple consumers to read in parallel.

When you want to test sending and receiving messages on a fresh topic.

Commands

This command creates a new Kafka topic named 'example-topic' with 3 partitions and a replication factor of 1, connecting to the Kafka server at localhost on port 9092.

Terminal

kafka-topics.sh --create --topic example-topic --bootstrap-server localhost:9092 --partitions 3 --replication-factor 1

Expected Output

Created topic example-topic.

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--topic - Name of the topic to create

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--partitions - Number of partitions for parallelism

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--replication-factor - Number of copies of data for fault tolerance

This command lists all topics currently available on the Kafka server to verify that 'example-topic' was created.

Terminal

kafka-topics.sh --list --bootstrap-server localhost:9092

Expected Output

example-topic

__consumer_offsets

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--list - List all topics

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--bootstrap-server - Kafka server address

This command shows detailed information about the 'example-topic', including partition count and replication details.

Terminal

kafka-topics.sh --describe --topic example-topic --bootstrap-server localhost:9092

Expected Output

Topic: example-topic	PartitionCount: 3	ReplicationFactor: 1	Configs: 

	Topic: example-topic	Partition: 0	Leader: 0	Replicas: 0	Isr: 0

	Topic: example-topic	Partition: 1	Leader: 0	Replicas: 0	Isr: 0

	Topic: example-topic	Partition: 2	Leader: 0	Replicas: 0	Isr: 0

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--describe - Show topic details

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--topic - Specify the topic to describe

Key Concept

If you remember nothing else from this pattern, remember: creating a Kafka topic sets up a named place to store and organize messages with partitions and replication for performance and safety.

Common Mistakes

Not specifying the replication factor when creating a topic

Kafka requires a replication factor to know how many copies of data to keep; missing it causes an error or defaults that may not suit your needs.

Always include --replication-factor with a valid number when creating a topic.

Using the wrong Kafka server address in --bootstrap-server

If the address is wrong, the command cannot connect to Kafka and fails to create or list topics.

Use the correct hostname and port where your Kafka broker is running, like localhost:9092.

Trying to create a topic that already exists without checking

Kafka will return an error saying the topic exists, causing confusion or script failure.

List existing topics first with --list to avoid duplicates before creating a new topic.

Summary

Use kafka-topics.sh with --create to make a new topic with partitions and replication.

Verify topic creation by listing all topics with --list.

Check topic details like partitions and replicas with --describe.