New to KubeDB? Please start here.

Vertical Scale Redis Cluster

This guide will show you how to use KubeDB Enterprise operator to update the resources of a Redis cluster database.

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 Community and Enterprise operator in your cluster following the steps here.

• You should be familiar with the following KubeDB concepts:

  • Redis
  • RedisOpsRequest
  • Vertical 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

Note: YAML files used in this tutorial are stored in docs/examples/redis directory of kubedb/docs repository.

Apply Vertical Scaling on Cluster

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

Prepare Redis Cluster Database

Now, we are going to deploy a Redis cluster database with version 6.2.14.

Deploy Redis Cluster

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

apiVersion: kubedb.com/v1alpha2
kind: Redis
metadata:
  name: redis-cluster
  namespace: demo
spec:
  version: 7.0.14
  mode: Cluster
  cluster:
    master: 3
    replicas: 1
  storageType: Durable
  storage:
    resources:
      requests:
        storage: "1Gi"
    storageClassName: "standard"
    accessModes:
      - ReadWriteOnce
  podTemplate:
    spec:
      resources:
        requests:
          cpu: "100m"
          memory: "100Mi"
  terminationPolicy: Halt

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

$ kubectl create -f https://github.com/kubedb/docs/raw/v2023.12.28/docs/examples/redis/scaling/vertical-scaling/rd-cluster.yaml
redis.kubedb.com/redis-cluster created

Now, wait until rd-cluster has status Ready. i.e. ,

$ kubectl get redis -n demo
NAME            VERSION   STATUS   AGE
redis-cluster   7.0.14     Ready    7m

Let’s check the Pod containers resources,

$ kubectl get pod -n demo redis-cluster-shard0-0 -o json | jq '.spec.containers[].resources'
{
  "limits": {
    "memory": "100Mi"
  },
  "requests": {
    "cpu": "100m",
    "memory": "100Mi"
  }
}

$ kubectl get pod -n demo redis-cluster-shard1-1 -o json | jq '.spec.containers[].resources'
{
  "limits": {
    "memory": "100Mi"
  },
  "requests": {
    "cpu": "100m",
    "memory": "100Mi"
  }
}

We can see from the above output that there are some default resources set by the operator for pods across all shards. And the scheduler will choose the best suitable node to place the container of the Pod.

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

Vertical Scaling

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

Create RedisOpsRequest

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

apiVersion: ops.kubedb.com/v1alpha1
kind: RedisOpsRequest
metadata:
  name: redisops-vertical
  namespace: demo
spec:
  type: VerticalScaling
  databaseRef:
    name: redis-cluster
  verticalScaling:
    redis:
      resources:
        requests:
          memory: "300Mi"
          cpu: "200m"
        limits:
          memory: "800Mi"
          cpu: "500m"

Here,

• spec.databaseRef.name specifies that we are performing vertical scaling operation on redis-cluster database.
• spec.type specifies that we are performing VerticalScaling on our database.
• spec.verticalScaling.redis specifies the desired resources after scaling.

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

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2023.12.28/docs/examples/redis/scaling/vertical-scaling/vertical-cluster.yaml
redisopsrequest.ops.kubedb.com/redisops-vertical created

Verify Redis Cluster resources updated successfully

If everything goes well, KubeDB Enterprise operator will update the resources of Redis object and related StatefulSets and Pods.

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

$ watch kubectl get redisopsrequest -n demo redisops-vertical
NAME                TYPE              STATUS       AGE
redisops-vertical   VerticalScaling   Successful   6m11s

We can see from the above output that the RedisOpsRequest has succeeded.

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

$ kubectl get pod -n demo redis-cluster-shard0-0 -o json | jq '.spec.containers[].resources'
{
  "limits": {
    "cpu": "500m",
    "memory": "800Mi"
  },
  "requests": {
    "cpu": "200m",
    "memory": "300Mi"
  }
}
$ kubectl get pod -n demo redis-cluster-shard1-1 -o json | jq '.spec.containers[].resources'
{
  "limits": {
    "cpu": "500m",
    "memory": "800Mi"
  },
  "requests": {
    "cpu": "200m",
    "memory": "300Mi"
  }
}

The above output verifies that we have successfully scaled up the resources of the Redis cluster database.

Cleaning up

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

$ kubectl patch -n demo rd/redis-cluster -p '{"spec":{"terminationPolicy":"WipeOut"}}' --type="merge"
redis.kubedb.com/redis-cluster patched

$ kubectl delete -n demo redis redis-cluster
redis.kubedb.com "redis-cluster" deleted

$ kubectl delete -n demo redisopsrequest redisops-vertical 
redisopsrequest.ops.kubedb.com "redisops-vertical " deleted