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Pgpool Horizontal Scaling

This guide will give an overview on how KubeDB Ops-manager operator scales up or down Pgpool replicas of PetSet.

Before You Begin

• You should be familiar with the following KubeDB concepts:
  • Pgpool
  • PgpoolOpsRequest

How Horizontal Scaling Process Works

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

2. KubeDB Provisioner operator watches the Pgpool CR.

3. When the operator finds a Pgpool CR, it creates PetSet and related necessary stuff like secrets, services, etc.

4. Then, in order to scale the PetSet of the Pgpool database the user creates a PgpoolOpsRequest CR with desired information.

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

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

9. After the successful scaling of the Pgpool replicas, the KubeDB Ops-manager operator resumes the Pgpool 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 Pgpool using PgpoolOpsRequest CRD.