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ClickHouse Compute Resource Autoscaling

This guide will give an overview on how KubeDB Autoscaler operator autoscales the database compute resources i.e. cpu and memory using ClickHouseautoscaler crd.

Before You Begin

• You should be familiar with the following KubeDB concepts:
  • ClickHouse
  • ClickHouseAutoscaler
  • ClickHouseOpsRequest

How Compute Autoscaling Works

  

The following diagram shows how KubeDB Autoscaler operator autoscales the resources of ClickHouse database components. Open the image in a new tab to see the enlarged version.

The Auto Scaling process consists of the following steps:

1. At first, a user creates a ClickHouse Custom Resource Object (CRO).

2. KubeDB Provisioner operator watches the ClickHouse CRO.

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

4. Then, in order to set up autoscaling of the of the ClickHouse cluster the user creates a ClickHouseAutoscaler CRO with desired configuration.

5. KubeDB Autoscaler operator watches the ClickHouseAutoscaler CRO.

6. KubeDB Autoscaler operator generates recommendation using the modified version of kubernetes official recommender for different components of the database, as specified in the ClickHouseAutoscaler CRO.

7. If the generated recommendation doesn’t match the current resources of the database, then KubeDB Autoscaler operator creates a ClickHouseOpsRequest CRO to scale the database to match the recommendation generated.

8. KubeDB Ops-manager operator watches the ClickHouseOpsRequest CRO.

9. Then the KubeDB Ops-manager operator will scale the database component vertically as specified on the ClickHouseOpsRequest CRO.

In the next docs, we are going to show a step by step guide on Autoscaling of various ClickHouse database components using ClickHouseAutoscaler CRD.