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Vertical Scale MongoDB Replicaset
This guide will show you how to use KubeDB Ops-manager 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
KubeDBProvisioner and Ops-manager 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 4.2.3.
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: "4.2.3"
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/v2023.06.19/docs/examples/mongodb/scaling/mg-replicaset.yaml
mongodb.kubedb.com/mg-replicaset created
Now, wait until mg-replicaset has status Ready. i.e,
$ kubectl get mg -n demo
NAME VERSION STATUS AGE
mg-replicaset 4.2.3 Ready 3m46s
Let’s check the Pod containers resources,
$ kubectl get pod -n demo mg-replicaset-0 -o json | jq '.spec.containers[].resources'
{
"limits": {
"cpu": "500m",
"memory": "1Gi"
},
"requests": {
"cpu": "500m",
"memory": "1Gi"
}
}
You can see the Pod has the default resources which is assigned by 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 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: "1.2Gi"
cpu: "0.6"
limits:
memory: "1.2Gi"
cpu: "0.6"
readinessCriteria:
oplogMaxLagSeconds: 20
objectsCountDiffPercentage: 10
timeout: 5m
apply: IfReady
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.spec.VerticalScaling.arbitercould also be specified in similar fashion to get the desired resources for arbiter pod.- Have a look here on the respective sections to understand the
readinessCriteria,timeout&applyfields.
Let’s create the MongoDBOpsRequest CR we have shown above,
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2023.06.19/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 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-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: <none>
API Version: ops.kubedb.com/v1alpha1
Kind: MongoDBOpsRequest
Metadata:
Creation Timestamp: 2022-10-26T10:41:56Z
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:replicaSet:
.:
f:limits:
.:
f:cpu:
f:memory:
f:requests:
.:
f:cpu:
f:memory:
Manager: kubectl-client-side-apply
Operation: Update
Time: 2022-10-26T10:41:56Z
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: 2022-10-26T10:44:33Z
Resource Version: 611468
UID: 474053a7-90a8-49fd-9b27-c9bf7b4660e7
Spec:
Apply: IfReady
Database Ref:
Name: mg-replicaset
Readiness Criteria:
Objects Count Diff Percentage: 10
Oplog Max Lag Seconds: 20
Timeout: 5m
Type: VerticalScaling
Vertical Scaling:
Replica Set:
Limits:
Cpu: 0.6
Memory: 1.2Gi
Requests:
Cpu: 0.6
Memory: 1.2Gi
Status:
Conditions:
Last Transition Time: 2022-10-26T10:43:21Z
Message: MongoDB ops request is vertically scaling database
Observed Generation: 1
Reason: VerticalScaling
Status: True
Type: VerticalScaling
Last Transition Time: 2022-10-26T10:44:33Z
Message: Successfully Vertically Scaled Replicaset Resources
Observed Generation: 1
Reason: UpdateReplicaSetResources
Status: True
Type: UpdateReplicaSetResources
Last Transition Time: 2022-10-26T10:44:33Z
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 82s KubeDB Ops-manager Operator Pausing MongoDB demo/mg-replicaset
Normal PauseDatabase 82s KubeDB Ops-manager Operator Successfully paused MongoDB demo/mg-replicaset
Normal Starting 82s KubeDB Ops-manager Operator Updating Resources of StatefulSet: mg-replicaset
Normal UpdateReplicaSetResources 82s KubeDB Ops-manager Operator Successfully updated replicaset Resources
Normal Starting 82s KubeDB Ops-manager Operator Updating Resources of StatefulSet: mg-replicaset
Normal UpdateReplicaSetResources 82s KubeDB Ops-manager Operator Successfully updated replicaset Resources
Normal UpdateReplicaSetResources 10s KubeDB Ops-manager Operator Successfully Vertically Scaled Replicaset Resources
Normal ResumeDatabase 10s KubeDB Ops-manager Operator Resuming MongoDB demo/mg-replicaset
Normal ResumeDatabase 10s KubeDB Ops-manager Operator Successfully resumed MongoDB demo/mg-replicaset
Normal Successful 10s KubeDB Ops-manager Operator Successfully Vertically 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": "600m",
"memory": "1288490188800m"
},
"requests": {
"cpu": "600m",
"memory": "1288490188800m"
}
}
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