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Vertical Scale MongoDB Standalone

This guide will show you how to use KubeDB Ops-manager operator to update the resources of a MongoDB standalone 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 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/mongodb directory of kubedb/docs repository.

Apply Vertical Scaling on Standalone

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

Prepare MongoDB Standalone Database

Now, we are going to deploy a MongoDB standalone database with version 4.2.3.

Deploy MongoDB standalone

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

apiVersion: kubedb.com/v1alpha2
kind: MongoDB
metadata:
  name: mg-standalone
  namespace: demo
spec:
  version: "4.2.3"
  storageType: Durable
  storage:
    storageClassName: "standard"
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi

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

$ kubectl create -f https://github.com/kubedb/docs/raw/v2023.01.17/docs/examples/mongodb/scaling/mg-standalone.yaml
mongodb.kubedb.com/mg-standalone created

Now, wait until mg-standalone has status Ready. i.e,

$ kubectl get mg -n demo
NAME            VERSION    STATUS    AGE
mg-standalone   4.2.3      Ready     5m56s

Let’s check the Pod containers resources,

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

You can see the Pod has default resources which is assigned by the Kubedb operator.

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

Vertical Scaling

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

Create MongoDBOpsRequest

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

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-vscale-standalone
  namespace: demo
spec:
  type: VerticalScaling
  databaseRef:
    name: mg-standalone
  verticalScaling:
    standalone:
      requests:
        memory: "2Gi"
        cpu: "1"
      limits:
        memory: "2Gi"
        cpu: "1"
  readinessCriteria:
    oplogMaxLagSeconds: 20
    objectsCountDiffPercentage: 10
  timeout: 5m
  apply: IfReady

Here,

  • spec.databaseRef.name specifies that we are performing vertical scaling operation on mops-vscale-standalone database.
  • spec.type specifies that we are performing VerticalScaling on our database.
  • spec.VerticalScaling.standalone specifies the desired resources after scaling.
  • Have a look here on the respective sections to understand the readinessCriteria, timeout & apply fields.

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

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2023.01.17/docs/examples/mongodb/scaling/vertical-scaling/mops-vscale-standalone.yaml
mongodbopsrequest.ops.kubedb.com/mops-vscale-standalone created

Verify MongoDB Standalone resources updated successfully

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

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

$ kubectl get mongodbopsrequest -n demo
Every 2.0s: kubectl get mongodbopsrequest -n demo
NAME                     TYPE              STATUS       AGE
mops-vscale-standalone   VerticalScaling   Successful   108s

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

$ kubectl describe mongodbopsrequest -n demo mops-vscale-standalone
Name:         mops-vscale-standalone
Namespace:    demo
Labels:       <none>
Annotations:  <none>
API Version:  ops.kubedb.com/v1alpha1
Kind:         MongoDBOpsRequest
Metadata:
  Creation Timestamp:  2022-10-26T10:54:01Z
  Generation:          1
  Managed Fields:
    API Version:  ops.kubedb.com/v1alpha1
    Fields Type:  FieldsV1
    fieldsV1:
      f:metadata:
        f:annotations:
          .:
          f:kubectl.kubernetes.io/last-applied-configuration:
      f:spec:
        .:
        f:apply:
        f:databaseRef:
        f:readinessCriteria:
          .:
          f:objectsCountDiffPercentage:
          f:oplogMaxLagSeconds:
        f:timeout:
        f:type:
        f:verticalScaling:
          .:
          f:standalone:
            .:
            f:limits:
              .:
              f:cpu:
              f:memory:
            f:requests:
              .:
              f:cpu:
              f:memory:
    Manager:      kubectl-client-side-apply
    Operation:    Update
    Time:         2022-10-26T10:54:01Z
    API Version:  ops.kubedb.com/v1alpha1
    Fields Type:  FieldsV1
    fieldsV1:
      f:status:
        .:
        f:conditions:
        f:observedGeneration:
        f:phase:
    Manager:         kubedb-ops-manager
    Operation:       Update
    Subresource:     status
    Time:            2022-10-26T10:54:52Z
  Resource Version:  613933
  UID:               c3bf9c3d-cf96-49ae-877f-a895e0b1d280
Spec:
  Apply:  IfReady
  Database Ref:
    Name:  mg-standalone
  Readiness Criteria:
    Objects Count Diff Percentage:  10
    Oplog Max Lag Seconds:          20
  Timeout:                          5m
  Type:                             VerticalScaling
  Vertical Scaling:
    Standalone:
      Limits:
        Cpu:     1
        Memory:  2Gi
      Requests:
        Cpu:     1
        Memory:  2Gi
Status:
  Conditions:
    Last Transition Time:  2022-10-26T10:54:21Z
    Message:               MongoDB ops request is vertically scaling database
    Observed Generation:   1
    Reason:                VerticalScaling
    Status:                True
    Type:                  VerticalScaling
    Last Transition Time:  2022-10-26T10:54:51Z
    Message:               Successfully Vertically Scaled Standalone Resources
    Observed Generation:   1
    Reason:                UpdateStandaloneResources
    Status:                True
    Type:                  UpdateStandaloneResources
    Last Transition Time:  2022-10-26T10:54:52Z
    Message:               Successfully Vertically Scaled Database
    Observed Generation:   1
    Reason:                Successful
    Status:                True
    Type:                  Successful
  Observed Generation:     1
  Phase:                   Successful
Events:
  Type    Reason                     Age   From                         Message
  ----    ------                     ----  ----                         -------
  Normal  PauseDatabase              34s   KubeDB Ops-manager Operator  Pausing MongoDB demo/mg-standalone
  Normal  PauseDatabase              34s   KubeDB Ops-manager Operator  Successfully paused MongoDB demo/mg-standalone
  Normal  Starting                   34s   KubeDB Ops-manager Operator  Updating Resources of StatefulSet: mg-standalone
  Normal  UpdateStandaloneResources  34s   KubeDB Ops-manager Operator  Successfully updated standalone Resources
  Normal  Starting                   34s   KubeDB Ops-manager Operator  Updating Resources of StatefulSet: mg-standalone
  Normal  UpdateStandaloneResources  34s   KubeDB Ops-manager Operator  Successfully updated standalone Resources
  Normal  UpdateStandaloneResources  4s    KubeDB Ops-manager Operator  Successfully Vertically Scaled Standalone Resources
  Normal  UpdateStandaloneResources  4s    KubeDB Ops-manager Operator  Successfully Vertically Scaled Standalone Resources
  Normal  ResumeDatabase             4s    KubeDB Ops-manager Operator  Resuming MongoDB demo/mg-standalone
  Normal  ResumeDatabase             3s    KubeDB Ops-manager Operator  Successfully resumed MongoDB demo/mg-standalone
  Normal  Successful                 3s    KubeDB Ops-manager Operator  Successfully Vertically Scaled Database

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

$ kubectl get pod -n demo mg-standalone-0 -o json | jq '.spec.containers[].resources'
{
  "limits": {
    "cpu": "1",
    "memory": "2Gi"
  },
  "requests": {
    "cpu": "1",
    "memory": "2Gi"
  }
}

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

Cleaning Up

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

kubectl delete mg -n demo mg-standalone
kubectl delete mongodbopsrequest -n demo mops-vscale-standalone