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FerretDB Horizontal Scaling

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

Before You Begin

• You should be familiar with the following KubeDB concepts:
  • FerretDB
  • FerretDBOpsRequest

How Horizontal Scaling Process Works

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

2. KubeDB Provisioner operator watches the FerretDB CR.

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

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

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

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

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