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Horizontal Scale MaxScale

This guide will show you how to use KubeDB Ops-manager operator to scale MaxScale server.

Before You Begin

• At first, you need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using kind.

• Install KubeDB operator in your cluster following the steps here.

• You should be familiar with the following KubeDB concepts:

  • MariaDB
  • MariaDB Replication
  • MariaDBOpsRequest
  • Horizontal Scaling Overview

To keep everything isolated, we are going to use a separate namespace called demo throughout this tutorial.

$ kubectl create ns demo
namespace/demo created

Apply Horizontal Scaling on MaxScale Server

Here, we are going to deploy a MariaDB cluster in replication mode using a supported version by KubeDB operator. Then we are going to apply horizontal scaling on MaxScale server.

Deploy MariaDB Cluster

In this section, we are going to deploy a MariaDB cluster in replication mode. Below is the YAML of the MariaDB CR that we are going to create,

apiVersion: kubedb.com/v1
kind: MariaDB
metadata:
  name: md-replication
  namespace: demo
spec:
  version: "10.5.23"
  replicas: 3
  topology:
    mode: MariaDBReplication
    maxscale:
      replicas: 3
      enableUI: true
      storageType: Durable
      storage:
        accessModes:
          - ReadWriteOnce
        resources:
          requests:
            storage: 50Mi
  storageType: Durable
  storage:
    accessModes:
      - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
  deletionPolicy: WipeOut

Let’s create the MariaDB CR we have shown above,

$ kubectl create -f https://github.com/kubedb/docs/raw/v2025.8.31/docs/examples/mariadb/scaling/md-replication.yaml
mariadb.kubedb.com/md-replication created

Now, wait until md-replication has status Ready. i.e,

$ kubectl get mariadb -n demo
NAME             VERSION   STATUS   AGE
md-replication   10.5.23   Ready    2m8s

Let’s check the number of replicas Maxscale has from the MariaDB object, also the number of replicas the petset have,

$ kubectl get mariadb -n demo md-replication -o json | jq '.spec.topology.maxscale.replicas'
3
$ kubectl get petset -n demo md-replication-mx -o json | jq '.spec.replicas'
3

We can see from both command that the MaxScale has 3 replicas in the cluster.

Scale Up Replicas

Here, we are going to scale up the replicas of the replicaset to meet the desired number of replicas after scaling.

Create MariaDBOpsRequest

In order to scale up the replicas of the replicaset of the MaxScale server, we have to create a MariaDBOpsRequest CR with our desired replicas. Below is the YAML of the MariaDBOpsRequest CR that we are going to create,

apiVersion: ops.kubedb.com/v1alpha1
kind: MariaDBOpsRequest
metadata:
  name: maxscale-horizontal-scale-up
  namespace: demo
spec:
  type: HorizontalScaling
  databaseRef:
    name: md-replication
  horizontalScaling:
    maxscale: true
    member: 4

Here,

• spec.type specifies that we are performing HorizontalScaling on our database.
• spec.databaseRef.name specifies that we are performing horizontal scaling operation on md-replication database.
• spec.horizontalScaling.maxscale specifies that we are performing horizontal scaling operation on maxscale server. If false then horizontal scaling performs on mariadb database.
• spec.horizontalScaling.member specifies the desired replicas after scaling.

Let’s create the MariaDBOpsRequest CR we have shown above,

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2025.8.31/docs/examples/mariadb/scaling/horizontal-scaling/mx-hscale-up.yaml
mariadbopsrequest.ops.kubedb.com/maxscale-horizontal-scale-up created

Verify Cluster replicas scaled up successfully

If everything goes well, KubeDB Ops-manager operator will update the replicas of MaxScale object and related PetSets and Pods.

Let’s wait for MariaDBOpsRequest to be Successful. Run the following command to watch MariaDBOpsRequest CR,

$ watch kubectl get mariadbopsrequest -n demo
Every 2.0s: kubectl get mariadbopsrequest -n demo
NAME                           TYPE                STATUS       AGE
maxscale-horizontal-scale-up   HorizontalScaling   Successful   2m31s

We can see from the above output that the MariaDBOpsRequest has succeeded. Now, we are going to verify the number of replicas this database has from the MariaDB object, number of pods the petset have,

$ kubectl get mariadb -n demo md-replication -o json | jq '.spec.topology.maxscale.replicas'
4
$ kubectl get petset -n demo md-replication-mx -o json | jq '.spec.replicas'
4 

From all the above outputs we can see that the replicas of the MaxScale server is 4. That means we have successfully scaled up the replicas of the MaxScale server.

Scale Down Replicas

Here, we are going to scale down the replicas of the cluster to meet the desired number of replicas after scaling.

Create MariaDBOpsRequest

In order to scale down the replicas of the MaxScale server, we have to create a MariaDBOpsRequest CR with our desired replicas. Below is the YAML of the MariaDBOpsRequest CR that we are going to create,

apiVersion: ops.kubedb.com/v1alpha1
kind: MariaDBOpsRequest
metadata:
  name: maxscale-horizontal-scale-down
  namespace: demo
spec:
  type: HorizontalScaling
  databaseRef:
    name: md-replication
  horizontalScaling:
    maxscale: true
    member: 3

Here,

• spec.type specifies that we are performing HorizontalScaling on our database.
• spec.databaseRef.name specifies that we are performing horizontal scaling operation on md-replication database.
• spec.horizontalScaling.maxscale specifies that we are performing horizontal scaling operation on maxscale server. If false then horizontal scaling performs on mariadb database.
• spec.horizontalScaling.member specifies the desired replicas after scaling.

Let’s create the MariaDBOpsRequest CR we have shown above,

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2025.8.31/docs/examples/mariadb/scaling/horizontal-scaling/mx-hscale-down.yaml
mariadbopsrequest.ops.kubedb.com/maxscale-horizontal-scale-down created

Verify Cluster replicas scaled down successfully

If everything goes well, KubeDB Ops-manager operator will update the replicas of MaxScale object and related PetSets and Pods.

Let’s wait for MariaDBOpsRequest to be Successful. Run the following command to watch MariaDBOpsRequest CR,

$ watch kubectl get mariadbopsrequest -n demo
Every 2.0s: kubectl get mariadbopsrequest -n demo
NAME                             TYPE                STATUS       AGE
maxscale-horizontal-scale-down   HorizontalScaling   Successful   55s

We can see from the above output that the MariaDBOpsRequest has succeeded. Now, we are going to verify the number of replicas MaxScale server has from the MariaDB object, number of pods the petset have,

$ kubectl get mariadb -n demo md-replication -o json | jq '.spec.topology.maxscale.replicas'
3
$ kubectl get petset -n demo md-replication-mx -o json | jq '.spec.replicas'
3

From all the above outputs we can see that the replicas of the cluster is 3. That means we have successfully scaled down the replicas of the MaxScale server.

Cleaning Up

To clean up the Kubernetes resources created by this tutorial, run:

$ kubectl delete mariadb -n demo md-replication
$ kubectl delete mariadbopsrequest -n demo  maxscale-horizontal-scale-up maxscale-horizontal-scale-down
$ kubectl delete ns demo