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Elasticsearch Horizontal Scaling

This guide will give an overview on how KubeDB Ops-manager operator scales up or down Elasticsearch cluster replicas of various components.

Before You Begin

• You should be familiar with the following KubeDB concepts:
  • Elasticsearch
  • ElasticsearchOpsRequest

How Horizontal Scaling Process Works

The following diagram shows how KubeDB Ops-manager operator scales up or down Elasticsearch 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 Elasticsearch Custom Resource (CR).

2. KubeDB Provisioner operator watches the Elasticsearch CR.

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

4. Then, in order to scale the various components of the Elasticsearch cluster, the user creates a ElasticsearchOpsRequest CR with desired information.

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

6. When it finds a ElasticsearchOpsRequest CR, it halts the Elasticsearch object which is referred from the ElasticsearchOpsRequest. So, the KubeDB Provisioner operator doesn’t perform any operations on the Elasticsearch 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 ElasticsearchOpsRequest 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 Elasticsearch object to reflect the updated state.

9. After the successful scaling of the Elasticsearch replicas, the KubeDB Ops-manager operator resumes the Elasticsearch 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 Elasticsearch cluster using ElasticsearchOpsRequest CRD.