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Kafka Horizontal Scaling

This guide will give an overview on how KubeDB Ops-manager operator scales up or down Kafka cluster replicas of various component such as Combined, Broker, Controller.

Before You Begin

• You should be familiar with the following KubeDB concepts:
  • Kafka
  • KafkaOpsRequest

How Horizontal Scaling Process Works

The following diagram shows how KubeDB Ops-manager operator scales up or down Kafka database components. Open the image in a new tab to see the enlarged version.

  

The Horizontal scaling process consists of the following steps:

1. At first, a user creates a Kafka Custom Resource (CR).

2. KubeDB Provisioner operator watches the Kafka CR.

3. When the operator finds a Kafka CR, it creates required number of PetSets and related necessary stuff like secrets, services, etc.

4. Then, in order to scale the various components (ie. ReplicaSet, Shard, ConfigServer, Mongos, etc.) of the Kafka cluster, the user creates a KafkaOpsRequest CR with desired information.

5. KubeDB Ops-manager operator watches the KafkaOpsRequest CR.

6. When it finds a KafkaOpsRequest CR, it halts the Kafka object which is referred from the KafkaOpsRequest. So, the KubeDB Provisioner operator doesn’t perform any operations on the Kafka object during the horizontal scaling process.

7. Then the KubeDB Ops-manager operator will scale the related PetSet Pods to reach the expected number of replicas defined in the KafkaOpsRequest CR.

8. After the successfully scaling the replicas of the related PetSet Pods, the KubeDB Ops-manager operator updates the number of replicas in the Kafka object to reflect the updated state.

9. After the successful scaling of the Kafka replicas, the KubeDB Ops-manager operator resumes the Kafka object so that the KubeDB Provisioner operator resumes its usual operations.

In the next docs, we are going to show a step by step guide on horizontal scaling of Kafka cluster using KafkaOpsRequest CRD.