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Vertical Scale of Redis Sentinel

This guide will show you how to use KubeDB Enterprise operator to perform vertical scaling of Redis in Sentinel mode and RedisSentinel.

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:

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.

Prepare Redis Sentinel Database

Now, we are going to deploy a RedisSentinel instance with version 6.2.7 and a Redis database with version 6.2.5. Then, in the next section we are going to apply vertical scaling on the sentinel and the database using RedisOpsRequest CRD

Deploy RedisSentinel :

In this section, we are going to deploy a RedisSentinel instance. Below is the YAML of the RedisSentinel CR that we are going to create,

apiVersion: kubedb.com/v1alpha2
kind: RedisSentinel
metadata:
  name: sen-sample
  namespace: demo
spec:
  version: 6.2.7
  replicas: 3
  storageType: Durable
  storage:
    resources:
      requests:
        storage: 1Gi
    storageClassName: "standard"
    accessModes:
      - ReadWriteOnce
  podTemplate:
    spec:
      resources:
        requests:
          cpu: "100m"
          memory: "100Mi"
  terminationPolicy: DoNotTerminate

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

$ kubectl create -f https://github.com/kubedb/docs/raw/v2023.06.19/docs/examples/redis/scaling/vertical-scaling/sentinel.yaml
redissentinel.kubedb.com/sen-sample created

Now, wait until sen-sample created has status Ready. i.e,

$ kubectl get redissentinel -n demo
NAME         VERSION   STATUS   AGE
sen-sample   6.2.7     Ready    5m20s

Let’s check the Pod containers resources,

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

Deploy Redis :

In this section, we are going to deploy a Redis instance which will be monitored by previously created sen-sample. Below is the YAML of the Redis CR that we are going to create,

apiVersion: kubedb.com/v1alpha2
kind: Redis
metadata:
  name: rd-sample
  namespace: demo
spec:
  version: 6.2.5
  replicas: 3
  sentinelRef:
    name: sen-sample
    namespace: demo
  mode: Sentinel
  storageType: Durable
  storage:
    resources:
      requests:
        storage: 1Gi
    storageClassName: "standard"
    accessModes:
      - ReadWriteOnce
  podTemplate:
    spec:
      resources:
        requests:
          cpu: "100m"
          memory: "100Mi"
  terminationPolicy: DoNotTerminate

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

$ kubectl create -f https://github.com/kubedb/docs/raw/v2023.06.19/docs/examples/redis/scaling/vertical-scaling/rd-sentinel.yaml
redis.kubedb.com/rd-sample created

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

$ kubectl get redis -n demo
NAME        VERSION   STATUS   AGE
rd-sample   6.2.5     Ready    2m11s

Let’s check the Pod containers resources,

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

We are now ready to apply the RedisSentinelOpsRequest CR to vertical scale on sentinel and RedisOpsRequest CR to vertical scale database.

Vertical Scale RedisSentinel

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

Create RedisSentinelOpsRequest:

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

apiVersion: ops.kubedb.com/v1alpha1
kind: RedisSentinelOpsRequest
metadata:
  name: sen-ops-vertical
  namespace: demo
spec:
  type: VerticalScaling
  databaseRef:
    name: sen-sample
  verticalScaling:
    redissentinel:
      requests:
        memory: "300Mi"
        cpu: "200m"
      limits:
        memory: "800Mi"
        cpu: "500m"

Here,

spec.databaseRef.name specifies that we are performing operation on sen-sample RedisSentinel instance.
spec.type specifies that we are going to perform VerticalScaling on our database.
spec.verticalScaling.redissentinel specifies the desired resources after scaling.

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

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2023.06.19/docs/examples/redis/scaling/vertical-scaling/vertical-sentinel.yaml
redissentinelopsrequest.ops.kubedb.com/sen-ops-vertical created

Verify RedisSentinel resources updated successfully :

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

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

$ watch kubectl get redissentinelopsrequest -n demo
Every 2.0s: kubectl get redissentinelopsrequest -n demo
NAME               TYPE              STATUS       AGE
sen-ops-vertical   VerticalScaling   Successful   5m27s

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

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

$ kubectl get pod -n demo sen-sample-0 -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 sentinel instance.

Vertical Scale Redis

Here, we are going to update the resources of the redis 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: rd-ops-vertical
  namespace: demo
spec:
  type: VerticalScaling
  databaseRef:
    name: rd-sample
  verticalScaling:
    redis:
      requests:
        memory: "300Mi"
        cpu: "200m"
      limits:
        memory: "800Mi"
        cpu: "500m"

Here,

spec.databaseRef.name specifies that we are performing operation on rd-sample Redis database.
spec.type specifies that we are going to perform 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/v2023.06.19/docs/examples/redis/scaling/vertical-scaling/vertical-redis-sentinel.yaml
redisopsrequest.ops.kubedb.com/rd-ops-vertical created

Verify Redis resources updated successfully :

If everything goes well, KubeDB Enterprise operator will update the image 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
NAME              TYPE              STATUS       AGE
rd-ops-vertical   VerticalScaling   Successful   4m4s

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 database has updated to meet up the desired state, Let’s check,

$ kubectl get pod -n demo rd-sample-0 -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 database.

Cleaning Up

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

# Delete Redis and RedisOpsRequest
$ kubectl patch -n demo rd/rd-sample -p '{"spec":{"terminationPolicy":"WipeOut"}}' --type="merge"
redis.kubedb.com/rd-sample patched

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

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

# Delete RedisSentinel and RedisSentinelOpsRequest
$ kubectl patch -n demo redissentinel/sen-sample -p '{"spec":{"terminationPolicy":"WipeOut"}}' --type="merge"
redissentinel.kubedb.com/sen-sample patched

$ kubectl delete -n demo redissentinel sen-sample
redissentinel.kubedb.com "sen-sample" deleted

$ kubectl delete -n demo redissentinelopsrequests sen-ops-vertical 
redissentinelopsrequest.ops.kubedb.com "sen-ops-vertical" deleted

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