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Vertical Scale MongoDB Replicaset
This guide will show you how to use KubeDB Enterprise operator to update the resources of a MongoDB replicaset database.
Before You Begin
At first, you need to have a Kubernetes cluster, and the
kubectlcommand-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
KubeDBCommunity and Enterprise operator in your cluster following the steps here.You should be familiar with the following
KubeDBconcepts:
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 Replicaset
Here, we are going to deploy a MongoDB replicaset using a supported version by KubeDB operator. Then we are going to apply vertical scaling on it.
Prepare MongoDB Replicaset Database
Now, we are going to deploy a MongoDB replicaset database with version 3.6.8.
Deploy MongoDB replicaset
In this section, we are going to deploy a MongoDB replicaset 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-replicaset
namespace: demo
spec:
version: "3.6.8-v1"
replicaSet:
name: "replicaset"
replicas: 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/v2021.01.02-rc.0/docs/examples/mongodb/scaling/mg-replicaset.yaml
mongodb.kubedb.com/mg-replicaset created
Now, wait until mg-replicaset has status Running. i.e,
$ kubectl get mg -n demo 20:05:47
NAME VERSION STATUS AGE
mg-replicaset 3.6.8-v1 Running 3m46s
Let’s check the Pod containers resources,
$ kubectl get pod -n demo mg-replicaset-0 -o json | jq '.spec.containers[].resources'
{}
You can see the Pod has empty resources that means the scheduler will choose a random node to place the container of the Pod on by default.
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 replicaset 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-replicaset
namespace: demo
spec:
type: VerticalScaling
databaseRef:
name: mg-replicaset
verticalScaling:
replicaSet:
requests:
memory: "150Mi"
cpu: "0.1"
limits:
memory: "250Mi"
cpu: "0.2"
Here,
spec.databaseRef.namespecifies that we are performing vertical scaling operation onmops-vscale-replicasetdatabase.spec.typespecifies that we are performingVerticalScalingon our database.spec.VerticalScaling.replicaSetspecifies the desired resources after scaling.
Let’s create the MongoDBOpsRequest CR we have shown above,
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2021.01.02-rc.0/docs/examples/mongodb/scaling/vertical-scaling/mops-vscale-replicaset.yaml
mongodbopsrequest.ops.kubedb.com/mops-vscale-replicaset created
Verify MongoDB Replicaset resources updated successfully
If everything goes well, KubeDB Enterprise 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-replicaset VerticalScaling Successful 3m56s
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-replicaset
Name: mops-vscale-replicaset
Namespace: demo
Labels: <none>
Annotations: API Version: ops.kubedb.com/v1alpha1
Kind: MongoDBOpsRequest
Metadata:
Creation Timestamp: 2020-08-25T06:05:39Z
Finalizers:
kubedb.com
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:databaseRef:
.:
f:name:
f:type:
f:verticalScaling:
.:
f:replicaSet:
.:
f:limits:
.:
f:memory:
f:requests:
.:
f:memory:
Manager: kubectl
Operation: Update
Time: 2020-08-25T06:05:39Z
API Version: ops.kubedb.com/v1alpha1
Fields Type: FieldsV1
fieldsV1:
f:metadata:
f:finalizers:
f:spec:
f:verticalScaling:
f:replicaSet:
f:limits:
f:cpu:
f:requests:
f:cpu:
f:status:
.:
f:conditions:
f:observedGeneration:
f:phase:
Manager: kubedb-enterprise
Operation: Update
Time: 2020-08-25T06:09:19Z
Resource Version: 5034763
Self Link: /apis/ops.kubedb.com/v1alpha1/namespaces/demo/mongodbopsrequests/mops-vscale-replicaset
UID: 65c44484-9216-4767-a42a-20eb04391a9e
Spec:
Database Ref:
Name: mg-replicaset
Type: VerticalScaling
Vertical Scaling:
ReplicaSet:
Limits:
Cpu: 0.2
Memory: 250Mi
Requests:
Cpu: 0.1
Memory: 150Mi
Status:
Conditions:
Last Transition Time: 2020-08-25T06:05:39Z
Message: MongoDB ops request is being processed
Observed Generation: 1
Reason: Scaling
Status: True
Type: Scaling
Last Transition Time: 2020-08-25T06:05:39Z
Message: Successfully halted mongodb: mg-replicaset
Observed Generation: 1
Reason: HaltDatabase
Status: True
Type: HaltDatabase
Last Transition Time: 2020-08-25T06:05:39Z
Message: Successfully updated StatefulSets Resources
Observed Generation: 1
Reason: UpdateStatefulSetResources
Status: True
Type: UpdateStatefulSetResources
Last Transition Time: 2020-08-25T06:09:19Z
Message: Successfully updated ReplicaSet resources
Observed Generation: 1
Reason: UpdateReplicaSetResources
Status: True
Type: UpdateReplicaSetResources
Last Transition Time: 2020-08-25T06:09:19Z
Message: Successfully Resumed mongodb: mg-replicaset
Observed Generation: 1
Reason: ResumeDatabase
Status: True
Type: ResumeDatabase
Last Transition Time: 2020-08-25T06:09:19Z
Message: Successfully completed the modification process
Observed Generation: 1
Reason: Successful
Status: True
Type: Successful
Observed Generation: 1
Phase: Successful
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal HaltDatabase 4m38s KubeDB Enterprise Operator Pausing Mongodb mg-replicaset in Namespace demo
Normal HaltDatabase 4m38s KubeDB Enterprise Operator Successfully Halted Mongodb mg-replicaset in Namespace demo
Normal Starting 4m38s KubeDB Enterprise Operator Updating Resources of StatefulSet: mg-replicaset
Normal UpdateStatefulSetResources 4m38s KubeDB Enterprise Operator Successfully updated StatefulSets Resources
Normal UpdateReplicaSetResources 4m38s KubeDB Enterprise Operator Updating ReplicaSet Resources
Normal UpdateReplicaSetResources 3m38s KubeDB Enterprise Operator Successfully Updated Resources of Pod mg-replicaset-1
Normal UpdateReplicaSetResources 2m18s KubeDB Enterprise Operator Successfully Updated Resources of Pod mg-replicaset-2
Normal UpdateReplicaSetResources 58s KubeDB Enterprise Operator Successfully Updated Resources of Pod (master): mg-replicaset-0
Normal UpdateReplicaSetResources 58s KubeDB Enterprise Operator Successfully Updated ReplicaSet Resources
Normal ResumeDatabase 58s KubeDB Enterprise Operator Resuming MongoDB
Normal ResumeDatabase 58s KubeDB Enterprise Operator Successfully Resumed mongodb
Normal Successful 58s KubeDB Enterprise Operator Successfully Scaled Database
Now, we are going to verify from one of the Pod yaml whether the resources of the replicaset database has updated to meet up the desired state, Let’s check,
$ kubectl get pod -n demo mg-replicaset-0 -o json | jq '.spec.containers[].resources'
{
"limits": {
"cpu": "200m",
"memory": "250Mi"
},
"requests": {
"cpu": "100m",
"memory": "150Mi"
}
}
The above output verifies that we have successfully scaled up the resources of the MongoDB replicaset database.
Cleaning Up
To clean up the Kubernetes resources created by this tutorial, run:
kubectl delete mg -n demo mg-replicaset
kubectl delete mongodbopsrequest -n demo mops-vscale-replicaset