New to KubeDB? Please start here.

Vertical Scale Memcached

This guide will show you how to use KubeDB Enterprise operator to update the resources of a Memcached 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:

  • Memcached
  • MemcachedOpsRequest
  • 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/memcached directory of kubedb/docs repository.

Apply Vertical Scaling on Memcahced

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

Prepare Memcahced Database

Now, we are going to deploy a Memcached database with version 1.6.22.

Deploy Memcahced

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

apiVersion: kubedb.com/v1
kind: Memcached
metadata:
  name: memcd-quickstart
  namespace: demo
spec:
  replicas: 1
  version: "1.6.22"
  podTemplate:
    spec:
      containers:
        - name: memcached
          resources:
            limits:
              cpu: 100m
              memory: 128Mi
            requests:
              cpu: 100m
              memory: 128Mi
  deletionPolicy: WipeOut

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

$ kubectl create -f https://github.com/kubedb/docs/raw/v2024.11.8-rc.0/docs/examples/memcached/scaling/memcached-vertical.yaml
memcached.kubedb.com/memcd-quickstart created

Now, wait until memcd-quickstart has status Ready. i.e. ,

$ kubectl get memcached -n demo
NAME               VERSION   STATUS   AGE
memcd-quickstart   1.6.22    Ready    5m

Let’s check the Pod containers resources,

$ kubectl get pod -n demo memcd-quickstart-0 -o json | jq '.spec.containers[].resources'
{
  "limits": {
    "cpu": "100m",
    "memory": "128Mi"
  },
  "requests": {
    "cpu": "100m",
    "memory": "128Mi"
  }
}

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

We are now ready to apply the MemcachedOpsRequest 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 MemcahedOpsRequest

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

apiVersion: ops.kubedb.com/v1alpha1
kind: MemcachedOpsRequest
metadata:
  name: memcached-mc
  namespace: demo
spec:
  type: VerticalScaling
  databaseRef:
    name: memcd-quickstart
  verticalScaling:
    memcached:
      resources:
        requests:
          memory: "400Mi"
          cpu: "500m"
        limits:
          memory: "400Mi"
          cpu: "500m"

Here,

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

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

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2024.11.8-rc.0/docs/examples/memcached/scaling/vertical-scaling.yaml
memcachedopsrequest.ops.kubedb.com/memcached-mc created

Verify Memcached Database resources updated successfully

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

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

$ watch kubectl get memcachedopsrequest -n demo
NAME                  TYPE                STATUS       AGE
memcached-mc          VerticalScaling     Successful   5m

We can see from the above output that the MemcachedOpsRequest has succeeded. Now, we are going to verify from the Pod yaml whether the resources of the Memcached database has updated to meet up the desired state, Let’s check,

$ kubectl get pod -n demo memcd-quickstart-0 -o json | jq '.spec.containers[].resources'
{
  "limits": {
    "cpu": "500m",
    "memory": "400Mi"
  },
  "requests": {
    "cpu": "500m",
    "memory": "400Mi"
  }
}

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

Cleaning up

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

$ kubectl patch -n demo mc/memcached-quickstart -p '{"spec":{"deletionPolicy":"WipeOut"}}' --type="merge"
memcached.kubedb.com/memcd-quickstart patched

$ kubectl delete -n demo memcached memcd-quickstart
memcached.kubedb.com "memcd-quickstart" deleted

$ kubectl delete memcachedopsrequest -n demo memcached-mc
memcachedopsrequest.ops.kubedb.com "memcached-mc" deleted