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Vertical Scale Hazelcast
This guide will show you how to use KubeDB Enterprise operator to update the resources of a Hazelcast database.
Before You Begin
At first, you need to have a Kubernetes cluster, and the
kubectlcommand-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
KubeDBCommunity and Enterprise operator in your cluster following the steps here.You should be familiar with the following
KubeDBconcepts:
To keep everything isolated, we are going to use a separate namespace called demo throughout this tutorial.
$ kubectl create ns demo
namespace/demo created
Note: YAML files used in this tutorial are stored in docs/examples/hazelcast folder in GitHub repository kubedb/docs.
Apply Vertical Scaling on Hazelcast
Here, we are going to deploy a Hazelcast database using a supported version by KubeDB operator. Then we are going to apply vertical scaling on it.
Prepare Hazelcast Database
Now, we are going to deploy a Hazelcast database with version 5.5.2.
Deploy Hazelcast
Before deploying hazelcast we need to create license secret since we are running enterprise version of hazelcast.
kubectl create secret generic hz-license-key -n demo --from-literal=licenseKey='your hazelcast licensekey'
secret/hz-license-key created
In this section, we are going to deploy a Hazelcast database. Then, in the next section we will update the resources using HazelcastOpsRequest CRD. Below is the YAML of the Hazelcast CR that we are going to create,
Let’s create the Hazelcast CR we have shown above,
$ kubectl create -f https://github.com/kubedb/docs/raw/v2025.12.9-rc.0/docs/examples/hazelcast/scaling/vertical-scaling/hazelcast.yaml
hazelcast.kubedb.com/hz-prod created
Now, wait until hz-prod has status Ready. i.e,
$ kubectl get hz -n demo
NAME TYPE VERSION STATUS AGE
hz-prod kubedb.com/v1alpha2 5.5.2 Ready 4m
Let’s check the container resources,
$ kubectl get pod -n demo hz-prod-0 -o json | jq '.spec.containers[].resources'
{
"limits": {
"memory": "1536Mi"
},
"requests": {
"cpu": "500m",
"memory": "1536Mi"
}
}
You can see the container has 500m CPU and 1Gi memory as resource limits.
We are now ready to apply the HazelcastOpsRequest CR to update the resources of this database.
Vertical Scaling
Here, we are going to update the resources of the database to meet the desired resources after scaling.
Create HazelcastOpsRequest
In order to update the resources of the database, we have to create a HazelcastOpsRequest CR with our desired resources. Below is the YAML of the HazelcastOpsRequest CR that we are going to create,
apiVersion: ops.kubedb.com/v1alpha1
kind: HazelcastOpsRequest
metadata:
name: hz-vscale-up
namespace: demo
spec:
databaseRef:
name: hz-prod
type: VerticalScaling
verticalScaling:
hazelcast:
resources:
limits:
cpu: 1
memory: 2.5Gi
requests:
cpu: 1
memory: 2.5Gi
Here,
spec.databaseRef.namespecifies that we are performing vertical scaling operation onhz-proddatabase.spec.typespecifies that we are performingVerticalScalingon our database.spec.verticalScaling.hazelcastspecifies the desired resources after scaling.
Let’s create the HazelcastOpsRequest CR we have shown above,
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2025.12.9-rc.0/docs/examples/hazelcast/scaling/vertical-scaling/hz-vscale-up.yaml
hazelcastopsrequest.ops.kubedb.com/hz-vscale-up created
Verify Hazelcast resources updated successfully
If everything goes well, KubeDB Enterprise operator will update the resources of Hazelcast object and related PetSets and Pods.
Let’s wait for HazelcastOpsRequest to be Successful. Run the following command to watch HazelcastOpsRequest CR,
$ kubectl get hazelcastopsrequest -n demo
NAME TYPE STATUS AGE
hz-vscale-up VerticalScaling Successful 3m2s
We can see from the above output that the HazelcastOpsRequest has succeeded. If we describe the HazelcastOpsRequest we will get an overview of the steps that were followed to update the database.
$ kubectl describe hazelcastopsrequest -n demo hz-vscale-up
Name: hz-vscale-up
Namespace: demo
Labels: <none>
Annotations: <none>
API Version: ops.kubedb.com/v1alpha1
Kind: HazelcastOpsRequest
Metadata:
Creation Timestamp: 2025-08-19T11:10:56Z
Generation: 1
Resource Version: 5478364
UID: e0c7e3a5-b04f-4756-a70f-aec54235b9ad
Spec:
Apply: IfReady
Database Ref:
Name: hz-prod
Type: VerticalScaling
Vertical Scaling:
Hazelcast:
Resources:
Limits:
Cpu: 1
Memory: 2.5Gi
Requests:
Cpu: 1
Memory: 2.5Gi
Status:
Conditions:
Last Transition Time: 2025-08-19T11:10:56Z
Message: Hazelcast ops-request has started to vertically scaling the Hazelcast nodes
Observed Generation: 1
Reason: VerticalScaling
Status: True
Type: VerticalScaling
Last Transition Time: 2025-08-19T11:11:00Z
Message: Successfully updated StatefulSets Resources
Observed Generation: 1
Reason: UpdateStatefulSets
Status: True
Type: UpdateStatefulSets
Last Transition Time: 2025-08-19T11:12:50Z
Message: Successfully Restarted Pods With Resources
Observed Generation: 1
Reason: RestartPods
Status: True
Type: RestartPods
Last Transition Time: 2025-08-19T11:11:10Z
Message: get pod; ConditionStatus:True; PodName:hz-prod-0
Observed Generation: 1
Status: True
Type: GetPod--hz-prod-0
Last Transition Time: 2025-08-19T11:11:10Z
Message: evict pod; ConditionStatus:True; PodName:hz-prod-0
Observed Generation: 1
Status: True
Type: EvictPod--hz-prod-0
Last Transition Time: 2025-08-19T11:11:20Z
Message: running pod; ConditionStatus:False
Observed Generation: 1
Status: False
Type: RunningPod
Last Transition Time: 2025-08-19T11:12:00Z
Message: get pod; ConditionStatus:True; PodName:hz-prod-1
Observed Generation: 1
Status: True
Type: GetPod--hz-prod-1
Last Transition Time: 2025-08-19T11:12:00Z
Message: evict pod; ConditionStatus:True; PodName:hz-prod-1
Observed Generation: 1
Status: True
Type: EvictPod--hz-prod-1
Last Transition Time: 2025-08-19T11:12:50Z
Message: Successfully completed the vertical scaling for RabbitMQ
Observed Generation: 1
Reason: Successful
Status: True
Type: Successful
Observed Generation: 1
Phase: Successful
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Starting 3m1s KubeDB Ops-manager Operator Start processing for HazelcastOpsRequest: demo/hz-vscale-up
Normal Starting 3m1s KubeDB Ops-manager Operator Pausing Hazelcast databse: demo/hz-prod
Normal Successful 3m KubeDB Ops-manager Operator Successfully paused Hazelcast database: demo/hz-prod for HazelcastOpsRequest: hz-vscale-up
Normal UpdateStatefulSets 2m57s KubeDB Ops-manager Operator Successfully updated StatefulSets Resources
Warning get pod; ConditionStatus:True; PodName:hz-prod-0 2m47s KubeDB Ops-manager Operator get pod; ConditionStatus:True; PodName:hz-prod-0
Warning evict pod; ConditionStatus:True; PodName:hz-prod-0 2m47s KubeDB Ops-manager Operator evict pod; ConditionStatus:True; PodName:hz-prod-0
Warning running pod; ConditionStatus:False 2m37s KubeDB Ops-manager Operator running pod; ConditionStatus:False
Warning get pod; ConditionStatus:True; PodName:hz-prod-1 117s KubeDB Ops-manager Operator get pod; ConditionStatus:True; PodName:hz-prod-1
Warning evict pod; ConditionStatus:True; PodName:hz-prod-1 117s KubeDB Ops-manager Operator evict pod; ConditionStatus:True; PodName:hz-prod-1
Normal RestartPods 67s KubeDB Ops-manager Operator Successfully Restarted Pods With Resources
Normal Starting 67s KubeDB Ops-manager Operator Resuming Hazelcast database: demo/hz-prod
Normal Successful 67s KubeDB Ops-manager Operator Successfully resumed Hazelcast database: demo/hz-prod for HazelcastOpsRequest: hz-vscale-up
Now, we are going to verify from the Pod, and the PetSet that the resources of the database has updated to meet up the desired state, Let’s check,
$ kubectl get pod -n demo hz-prod-0 -o json | jq '.spec.containers[].resources'
{
"limits": {
"memory": "1536Mi"
},
"requests": {
"cpu": "500m",
"memory": "1536Mi"
}
}
The above output verifies that we have successfully scaled up the resources of the Hazelcast database.
Cleaning up
To cleanup the Kubernetes resources created by this tutorial, run:
kubectl delete hazelcastopsrequest -n demo hz-vscale-up
kubectl delete hazelcast -n demo hz-prod
kubectl delete ns demo
Next Steps
- Detail concepts of Hazelcast object.
- Monitor your Hazelcast database with KubeDB using out-of-the-box Prometheus operator.
- Want to hack on KubeDB? Check our contribution guidelines.