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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 Sharded Database
Here, we are going to deploy a MongoDB sharded database using a supported version by KubeDB operator. Then we are going to apply vertical scaling on it.
Prepare MongoDB Sharded Database
Now, we are going to deploy a MongoDB sharded database with version 4.2.3.
Deploy MongoDB Sharded Database
In this section, we are going to deploy a MongoDB sharded database. Then, in the next sections we will update the resources of various components (mongos, shard, configserver etc.) 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-sharding
namespace: demo
spec:
version: 4.2.3
shardTopology:
configServer:
replicas: 3
storage:
resources:
requests:
storage: 1Gi
storageClassName: standard
mongos:
replicas: 2
shard:
replicas: 3
shards: 2
storage:
resources:
requests:
storage: 1Gi
storageClassName: standard
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-shard.yaml
mongodb.kubedb.com/mg-sharding created
Now, wait until mg-sharding has status Ready. i.e,
$ kubectl get mg -n demo
NAME VERSION STATUS AGE
mg-sharding 4.2.3 Ready 8m51s
Let’s check the Pod containers resources of various components (mongos, shard, configserver etc.) of the database,
$ kubectl get pod -n demo mg-sharding-mongos-0 -o json | jq '.spec.containers[].resources'
{
"limits": {
"cpu": "500m",
"memory": "1Gi"
},
"requests": {
"cpu": "500m",
"memory": "1Gi"
}
}
$ kubectl get pod -n demo mg-sharding-configsvr-0 -o json | jq '.spec.containers[].resources'
{
"limits": {
"cpu": "500m",
"memory": "1Gi"
},
"requests": {
"cpu": "500m",
"memory": "1Gi"
}
}
$ kubectl get pod -n demo mg-sharding-shard0-0 -o json | jq '.spec.containers[].resources'
{
"limits": {
"cpu": "500m",
"memory": "1Gi"
},
"requests": {
"cpu": "500m",
"memory": "1Gi"
}
}
You can see all the Pod of mongos, configserver and shard has default resources which is assigned by Kubedb operator.
We are now ready to apply the MongoDBOpsRequest CR to update the resources of mongos, configserver and shard nodes of this database.
Vertical Scaling of Shard
Here, we are going to update the resources of the shard of the database to meet the desired resources after scaling.
Create MongoDBOpsRequest for shard
In order to update the resources of the shard nodes, 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-shard
namespace: demo
spec:
type: VerticalScaling
databaseRef:
name: mg-sharding
verticalScaling:
shard:
requests:
memory: "1100Mi"
cpu: "0.55"
limits:
memory: "1100Mi"
cpu: "0.55"
configServer:
requests:
memory: "1100Mi"
cpu: "0.55"
limits:
memory: "1100Mi"
cpu: "0.55"
mongos:
requests:
memory: "1100Mi"
cpu: "0.55"
limits:
memory: "1100Mi"
cpu: "0.55"
readinessCriteria:
oplogMaxLagSeconds: 20
objectsCountDiffPercentage: 10
timeout: 5m
apply: IfReady
Here,
spec.databaseRef.namespecifies that we are performing vertical scaling operation onmops-vscale-sharddatabase.spec.typespecifies that we are performingVerticalScalingon our database.spec.VerticalScaling.shardspecifies the desired resources after scaling for the shard nodes.spec.VerticalScaling.configServerspecifies the desired resources after scaling for the configServer nodes.spec.VerticalScaling.mongosspecifies the desired resources after scaling for the mongos nodes.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.
Note: If you don’t want to scale all the components together, you can only specify the components (shard, configServer and mongos) that you want to scale.
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-shard.yaml
mongodbopsrequest.ops.kubedb.com/mops-vscale-shard created
Verify MongoDB Shard resources updated successfully
If everything goes well, KubeDB Ops-manager operator will update the resources of MongoDB object and related StatefulSets and Pods of shard nodes.
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-shard VerticalScaling Successful 8m21s
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-shard
Name: mops-vscale-shard
Namespace: demo
Labels: <none>
Annotations: <none>
API Version: ops.kubedb.com/v1alpha1
Kind: MongoDBOpsRequest
Metadata:
Creation Timestamp: 2022-10-26T10:45:56Z
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:configServer:
.:
f:limits:
.:
f:cpu:
f:memory:
f:requests:
.:
f:cpu:
f:memory:
f:mongos:
.:
f:limits:
.:
f:cpu:
f:memory:
f:requests:
.:
f:cpu:
f:memory:
f:shard:
.:
f:limits:
.:
f:cpu:
f:memory:
f:requests:
.:
f:cpu:
f:memory:
Manager: kubectl-client-side-apply
Operation: Update
Time: 2022-10-26T10:45:56Z
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: 2022-10-26T10:52:28Z
Resource Version: 613274
UID: a186cc72-3629-4034-bbf8-988839f6ec23
Spec:
Apply: IfReady
Database Ref:
Name: mg-sharding
Readiness Criteria:
Objects Count Diff Percentage: 10
Oplog Max Lag Seconds: 20
Timeout: 5m
Type: VerticalScaling
Vertical Scaling:
Config Server:
Limits:
Cpu: 0.55
Memory: 1100Mi
Requests:
Cpu: 0.55
Memory: 1100Mi
Mongos:
Limits:
Cpu: 0.55
Memory: 1100Mi
Requests:
Cpu: 0.55
Memory: 1100Mi
Shard:
Limits:
Cpu: 0.55
Memory: 1100Mi
Requests:
Cpu: 0.55
Memory: 1100Mi
Status:
Conditions:
Last Transition Time: 2022-10-26T10:48:06Z
Message: MongoDB ops request is vertically scaling database
Observed Generation: 1
Reason: VerticalScaling
Status: True
Type: VerticalScaling
Last Transition Time: 2022-10-26T10:49:37Z
Message: Successfully Vertically Scaled ConfigServer Resources
Observed Generation: 1
Reason: UpdateConfigServerResources
Status: True
Type: UpdateConfigServerResources
Last Transition Time: 2022-10-26T10:50:07Z
Message: Successfully Vertically Scaled Mongos Resources
Observed Generation: 1
Reason: UpdateMongosResources
Status: True
Type: UpdateMongosResources
Last Transition Time: 2022-10-26T10:52:28Z
Message: Successfully Vertically Scaled Shard Resources
Observed Generation: 1
Reason: UpdateShardResources
Status: True
Type: UpdateShardResources
Last Transition Time: 2022-10-26T10:52:28Z
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 4m51s KubeDB Ops-manager Operator Successfully paused MongoDB demo/mg-sharding
Normal Starting 4m51s KubeDB Ops-manager Operator Updating Resources of StatefulSet: mg-sharding-configsvr
Normal UpdateConfigServerResources 4m51s KubeDB Ops-manager Operator Successfully updated configServer Resources
Normal Starting 4m51s KubeDB Ops-manager Operator Updating Resources of StatefulSet: mg-sharding-configsvr
Normal UpdateConfigServerResources 4m51s KubeDB Ops-manager Operator Successfully updated configServer Resources
Normal PauseDatabase 4m51s KubeDB Ops-manager Operator Pausing MongoDB demo/mg-sharding
Normal UpdateConfigServerResources 3m20s KubeDB Ops-manager Operator Successfully Vertically Scaled ConfigServer Resources
Normal Starting 3m20s KubeDB Ops-manager Operator Updating Resources of StatefulSet: mg-sharding-mongos
Normal UpdateMongosResources 3m20s KubeDB Ops-manager Operator Successfully updated Mongos Resources
Normal UpdateShardResources 2m50s KubeDB Ops-manager Operator Successfully updated Shard Resources
Normal Starting 2m50s KubeDB Ops-manager Operator Updating Resources of StatefulSet: mg-sharding-shard0
Normal Starting 2m50s KubeDB Ops-manager Operator Updating Resources of StatefulSet: mg-sharding-shard1
Normal UpdateMongosResources 2m50s KubeDB Ops-manager Operator Successfully Vertically Scaled Mongos Resources
Normal UpdateShardResources 29s KubeDB Ops-manager Operator Successfully Vertically Scaled Shard Resources
Normal ResumeDatabase 29s KubeDB Ops-manager Operator Resuming MongoDB demo/mg-sharding
Normal ResumeDatabase 29s KubeDB Ops-manager Operator Successfully resumed MongoDB demo/mg-sharding
Normal Successful 29s KubeDB Ops-manager Operator Successfully Vertically Scaled Database
Normal UpdateShardResources 28s KubeDB Ops-manager Operator Successfully Vertically Scaled Shard Resources
Now, we are going to verify from one of the Pod yaml whether the resources of the shard nodes has updated to meet up the desired state, Let’s check,
$ kubectl get pod -n demo mg-sharding-shard0-0 -o json | jq '.spec.containers[].resources'
{
"limits": {
"cpu": "550m",
"memory": "1100Mi"
},
"requests": {
"cpu": "550m",
"memory": "1100Mi"
}
}
$ kubectl get pod -n demo mg-sharding-configsvr-0 -o json | jq '.spec.containers[].resources'
{
"limits": {
"cpu": "550m",
"memory": "1100Mi"
},
"requests": {
"cpu": "550m",
"memory": "1100Mi"
}
}
$ kubectl get pod -n demo mg-sharding-mongos-0 -o json | jq '.spec.containers[].resources'
{
"limits": {
"cpu": "550m",
"memory": "1100Mi"
},
"requests": {
"cpu": "550m",
"memory": "1100Mi"
}
}
The above output verifies that we have successfully scaled the resources of all components of the MongoDB sharded database.
Cleaning Up
To clean up the Kubernetes resources created by this tutorial, run:
kubectl delete mg -n demo mg-shard
kubectl delete mongodbopsrequest -n demo mops-vscale-shard