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Vertical Scale Kafka Topology Cluster

This guide will show you how to use KubeDB Ops-manager operator to update the resources of a Kafka topology cluster.

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 Provisioner and Ops-manager operator in your cluster following the steps here.
You should be familiar with the following KubeDB concepts:

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/kafka directory of kubedb/docs repository.

Apply Vertical Scaling on Topology Cluster

Here, we are going to deploy a Kafka topology cluster using a supported version by KubeDB operator. Then we are going to apply vertical scaling on it.

Prepare Kafka Topology Cluster

Now, we are going to deploy a Kafka topology cluster database with version 3.6.1.

Deploy Kafka Topology Cluster

In this section, we are going to deploy a Kafka topology cluster. Then, in the next section we will update the resources of the database using KafkaOpsRequest CRD. Below is the YAML of the Kafka CR that we are going to create,

apiVersion: kubedb.com/v1
kind: Kafka
metadata:
  name: kafka-prod
  namespace: demo
spec:
  version: 3.6.1
  topology:
    broker:
      replicas: 2
      storage:
        accessModes:
          - ReadWriteOnce
        resources:
          requests:
            storage: 1Gi
        storageClassName: standard
    controller:
      replicas: 2
      storage:
        accessModes:
          - ReadWriteOnce
        resources:
          requests:
            storage: 1Gi
        storageClassName: standard
  storageType: Durable
  deletionPolicy: WipeOut

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

$ kubectl create -f https://github.com/kubedb/docs/raw/v2024.9.30/docs/examples/kafka/scaling/kafka-topology.yaml
kafka.kubedb.com/kafka-prod created

Now, wait until kafka-prod has status Ready. i.e,

$ kubectl get kf -n demo -w
NAME          TYPE            VERSION   STATUS         AGE
kafka-prod    kubedb.com/v1   3.6.1     Provisioning   0s
kafka-prod    kubedb.com/v1   3.6.1     Provisioning   24s
.
.
kafka-prod    kubedb.com/v1   3.6.1     Ready          92s

Let’s check the Pod containers resources for both broker and controller of the Kafka topology cluster. Run the following command to get the resources of the broker and controller containers of the Kafka topology cluster

$ kubectl get pod -n demo kafka-prod-broker-0 -o json | jq '.spec.containers[].resources'
{
  "limits": {
    "memory": "1Gi"
  },
  "requests": {
    "cpu": "500m",
    "memory": "1Gi"
  }
}

$ kubectl get pod -n demo kafka-prod-controller-0 -o json | jq '.spec.containers[].resources'
{
  "limits": {
    "memory": "1Gi"
  },
  "requests": {
    "cpu": "500m",
    "memory": "1Gi"
  }
}

This is the default resources of the Kafka topology cluster set by the KubeDB operator.

We are now ready to apply the KafkaOpsRequest CR to update the resources of this database.

Vertical Scaling

Here, we are going to update the resources of the topology cluster to meet the desired resources after scaling.

Create KafkaOpsRequest

In order to update the resources of the database, we have to create a KafkaOpsRequest CR with our desired resources. Below is the YAML of the KafkaOpsRequest CR that we are going to create,

apiVersion: ops.kubedb.com/v1alpha1
kind: KafkaOpsRequest
metadata:
  name: kfops-vscale-topology
  namespace: demo
spec:
  type: VerticalScaling
  databaseRef:
    name: kafka-prod
  verticalScaling:
    broker:
      resources:
        requests:
          memory: "1.2Gi"
          cpu: "0.6"
        limits:
          memory: "1.2Gi"
          cpu: "0.6"
    controller:
      resources:
        requests:
          memory: "1.1Gi"
          cpu: "0.6"
        limits:
          memory: "1.1Gi"
          cpu: "0.6"
  timeout: 5m
  apply: IfReady

Here,

spec.databaseRef.name specifies that we are performing vertical scaling operation on kafka-prod cluster.
spec.type specifies that we are performing VerticalScaling on kafka.
spec.VerticalScaling.node specifies the desired resources after scaling.

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

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2024.9.30/docs/examples/kafka/scaling/vertical-scaling/kafka-vertical-scaling-topology.yaml
kafkaopsrequest.ops.kubedb.com/kfops-vscale-topology created

Verify Kafka Topology cluster resources updated successfully

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

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

$ kubectl get kafkaopsrequest -n demo
NAME                     TYPE              STATUS       AGE
kfops-vscale-topology    VerticalScaling   Successful   3m56s

We can see from the above output that the KafkaOpsRequest has succeeded. If we describe the KafkaOpsRequest we will get an overview of the steps that were followed to scale the cluster.

$ kubectl describe kafkaopsrequest -n demo kfops-vscale-topology
Name:         kfops-vscale-topology
Namespace:    demo
Labels:       <none>
Annotations:  <none>
API Version:  ops.kubedb.com/v1alpha1
Kind:         KafkaOpsRequest
Metadata:
  Creation Timestamp:  2024-08-02T06:09:46Z
  Generation:          1
  Resource Version:    337300
  UID:                 ca298c0a-e08d-4c78-acbc-40eb5e96532d
Spec:
  Apply:  IfReady
  Database Ref:
    Name:   kafka-prod
  Timeout:  5m
  Type:     VerticalScaling
  Vertical Scaling:
    Broker:
      Resources:
        Limits:
          Cpu:     0.6
          Memory:  1.2Gi
        Requests:
          Cpu:     0.6
          Memory:  1.2Gi
    Controller:
      Resources:
        Limits:
          Cpu:     0.6
          Memory:  1.1Gi
        Requests:
          Cpu:     0.6
          Memory:  1.1Gi
Status:
  Conditions:
    Last Transition Time:  2024-08-02T06:09:46Z
    Message:               Kafka ops-request has started to vertically scaling the kafka nodes
    Observed Generation:   1
    Reason:                VerticalScaling
    Status:                True
    Type:                  VerticalScaling
    Last Transition Time:  2024-08-02T06:09:50Z
    Message:               Successfully updated PetSets Resources
    Observed Generation:   1
    Reason:                UpdatePetSets
    Status:                True
    Type:                  UpdatePetSets
    Last Transition Time:  2024-08-02T06:09:55Z
    Message:               get pod; ConditionStatus:True; PodName:kafka-prod-broker-0
    Observed Generation:   1
    Status:                True
    Type:                  GetPod--kafka-prod-broker-0
    Last Transition Time:  2024-08-02T06:09:55Z
    Message:               evict pod; ConditionStatus:True; PodName:kafka-prod-broker-0
    Observed Generation:   1
    Status:                True
    Type:                  EvictPod--kafka-prod-broker-0
    Last Transition Time:  2024-08-02T06:10:00Z
    Message:               check pod running; ConditionStatus:True; PodName:kafka-prod-broker-0
    Observed Generation:   1
    Status:                True
    Type:                  CheckPodRunning--kafka-prod-broker-0
    Last Transition Time:  2024-08-02T06:10:05Z
    Message:               get pod; ConditionStatus:True; PodName:kafka-prod-broker-1
    Observed Generation:   1
    Status:                True
    Type:                  GetPod--kafka-prod-broker-1
    Last Transition Time:  2024-08-02T06:10:05Z
    Message:               evict pod; ConditionStatus:True; PodName:kafka-prod-broker-1
    Observed Generation:   1
    Status:                True
    Type:                  EvictPod--kafka-prod-broker-1
    Last Transition Time:  2024-08-02T06:10:15Z
    Message:               check pod running; ConditionStatus:True; PodName:kafka-prod-broker-1
    Observed Generation:   1
    Status:                True
    Type:                  CheckPodRunning--kafka-prod-broker-1
    Last Transition Time:  2024-08-02T06:10:20Z
    Message:               get pod; ConditionStatus:True; PodName:kafka-prod-controller-0
    Observed Generation:   1
    Status:                True
    Type:                  GetPod--kafka-prod-controller-0
    Last Transition Time:  2024-08-02T06:10:20Z
    Message:               evict pod; ConditionStatus:True; PodName:kafka-prod-controller-0
    Observed Generation:   1
    Status:                True
    Type:                  EvictPod--kafka-prod-controller-0
    Last Transition Time:  2024-08-02T06:10:35Z
    Message:               check pod running; ConditionStatus:True; PodName:kafka-prod-controller-0
    Observed Generation:   1
    Status:                True
    Type:                  CheckPodRunning--kafka-prod-controller-0
    Last Transition Time:  2024-08-02T06:10:40Z
    Message:               get pod; ConditionStatus:True; PodName:kafka-prod-controller-1
    Observed Generation:   1
    Status:                True
    Type:                  GetPod--kafka-prod-controller-1
    Last Transition Time:  2024-08-02T06:10:40Z
    Message:               evict pod; ConditionStatus:True; PodName:kafka-prod-controller-1
    Observed Generation:   1
    Status:                True
    Type:                  EvictPod--kafka-prod-controller-1
    Last Transition Time:  2024-08-02T06:10:55Z
    Message:               check pod running; ConditionStatus:True; PodName:kafka-prod-controller-1
    Observed Generation:   1
    Status:                True
    Type:                  CheckPodRunning--kafka-prod-controller-1
    Last Transition Time:  2024-08-02T06:11:00Z
    Message:               Successfully Restarted Pods With Resources
    Observed Generation:   1
    Reason:                RestartPods
    Status:                True
    Type:                  RestartPods
    Last Transition Time:  2024-08-02T06:11:00Z
    Message:               Successfully completed the vertical scaling for kafka
    Observed Generation:   1
    Reason:                Successful
    Status:                True
    Type:                  Successful
  Observed Generation:     1
  Phase:                   Successful
Events:
  Type     Reason                                                                     Age    From                         Message
  ----     ------                                                                     ----   ----                         -------
  Normal   Starting                                                                   3m32s  KubeDB Ops-manager Operator  Start processing for KafkaOpsRequest: demo/kfops-vscale-topology
  Normal   Starting                                                                   3m32s  KubeDB Ops-manager Operator  Pausing Kafka databse: demo/kafka-prod
  Normal   Successful                                                                 3m32s  KubeDB Ops-manager Operator  Successfully paused Kafka database: demo/kafka-prod for KafkaOpsRequest: kfops-vscale-topology
  Normal   UpdatePetSets                                                              3m28s  KubeDB Ops-manager Operator  Successfully updated PetSets Resources
  Warning  get pod; ConditionStatus:True; PodName:kafka-prod-broker-0                 3m23s  KubeDB Ops-manager Operator  get pod; ConditionStatus:True; PodName:kafka-prod-broker-0
  Warning  evict pod; ConditionStatus:True; PodName:kafka-prod-broker-0               3m23s  KubeDB Ops-manager Operator  evict pod; ConditionStatus:True; PodName:kafka-prod-broker-0
  Warning  check pod running; ConditionStatus:True; PodName:kafka-prod-broker-0       3m18s  KubeDB Ops-manager Operator  check pod running; ConditionStatus:True; PodName:kafka-prod-broker-0
  Warning  get pod; ConditionStatus:True; PodName:kafka-prod-broker-1                 3m13s  KubeDB Ops-manager Operator  get pod; ConditionStatus:True; PodName:kafka-prod-broker-1
  Warning  evict pod; ConditionStatus:True; PodName:kafka-prod-broker-1               3m13s  KubeDB Ops-manager Operator  evict pod; ConditionStatus:True; PodName:kafka-prod-broker-1
  Warning  check pod running; ConditionStatus:False; PodName:kafka-prod-broker-1      3m8s   KubeDB Ops-manager Operator  check pod running; ConditionStatus:False; PodName:kafka-prod-broker-1
  Warning  check pod running; ConditionStatus:True; PodName:kafka-prod-broker-1       3m3s   KubeDB Ops-manager Operator  check pod running; ConditionStatus:True; PodName:kafka-prod-broker-1
  Warning  get pod; ConditionStatus:True; PodName:kafka-prod-controller-0             2m58s  KubeDB Ops-manager Operator  get pod; ConditionStatus:True; PodName:kafka-prod-controller-0
  Warning  evict pod; ConditionStatus:True; PodName:kafka-prod-controller-0           2m58s  KubeDB Ops-manager Operator  evict pod; ConditionStatus:True; PodName:kafka-prod-controller-0
  Warning  check pod running; ConditionStatus:False; PodName:kafka-prod-controller-0  2m53s  KubeDB Ops-manager Operator  check pod running; ConditionStatus:False; PodName:kafka-prod-controller-0
  Warning  check pod running; ConditionStatus:True; PodName:kafka-prod-controller-0   2m43s  KubeDB Ops-manager Operator  check pod running; ConditionStatus:True; PodName:kafka-prod-controller-0
  Warning  get pod; ConditionStatus:True; PodName:kafka-prod-controller-1             2m38s  KubeDB Ops-manager Operator  get pod; ConditionStatus:True; PodName:kafka-prod-controller-1
  Warning  evict pod; ConditionStatus:True; PodName:kafka-prod-controller-1           2m38s  KubeDB Ops-manager Operator  evict pod; ConditionStatus:True; PodName:kafka-prod-controller-1
  Warning  check pod running; ConditionStatus:False; PodName:kafka-prod-controller-1  2m33s  KubeDB Ops-manager Operator  check pod running; ConditionStatus:False; PodName:kafka-prod-controller-1
  Warning  check pod running; ConditionStatus:True; PodName:kafka-prod-controller-1   2m23s  KubeDB Ops-manager Operator  check pod running; ConditionStatus:True; PodName:kafka-prod-controller-1
  Normal   RestartPods                                                                2m18s  KubeDB Ops-manager Operator  Successfully Restarted Pods With Resources
  Normal   Starting                                                                   2m18s  KubeDB Ops-manager Operator  Resuming Kafka database: demo/kafka-prod
  Normal   Successful                                                                 2m18s  KubeDB Ops-manager Operator  Successfully resumed Kafka database: demo/kafka-prod for KafkaOpsRequest: kfops-vscale-topology

Now, we are going to verify from one of the Pod yaml whether the resources of the topology cluster has updated to meet up the desired state, Let’s check,

$ kubectl get pod -n demo kafka-prod-broker-1 -o json | jq '.spec.containers[].resources'
{
  "limits": {
    "cpu": "600m",
    "memory": "1288490188800m"
  },
  "requests": {
    "cpu": "600m",
    "memory": "1288490188800m"
  }
}
$ kubectl get pod -n demo kafka-prod-controller-1 -o json | jq '.spec.containers[].resources'
{
  "limits": {
    "cpu": "600m",
    "memory": "1181116006400m"
  },
  "requests": {
    "cpu": "600m",
    "memory": "1181116006400m"
  }
}

The above output verifies that we have successfully scaled up the resources of the Kafka topology cluster.

Cleaning Up

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

kubectl delete kf -n demo kafka-prod
kubectl delete kafkaopsrequest -n demo kfops-vscale-topology
kubectl delete ns demo

Next Steps

Detail concepts of Kafka object.
Different Kafka topology clustering modes here.
Monitor your Kafka database with KubeDB using out-of-the-box Prometheus operator.

Want to hack on KubeDB? Check our contribution guidelines.

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