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Upgrade version of MongoDB Sharded Database

This guide will show you how to use KubeDB Enterprise operator to upgrade the version of MongoDB Sharded 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:

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.

Prepare MongoDB Sharded Database Database

Now, we are going to deploy a MongoDB sharded database with version 3.6.8.

Deploy MongoDB Sharded Database

In this section, we are going to deploy a MongoDB sharded database. Then, in the next section we will upgrade the version 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: 3.6.8-v1
  shardTopology:
    configServer:
      replicas: 2
      storage:
        resources:
          requests:
            storage: 1Gi
        storageClassName: standard
    mongos:
      replicas: 2
    shard:
      replicas: 2
      shards: 3
      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/v2021.04.16/docs/examples/mongodb/upgrading/mg-shard.yaml
mongodb.kubedb.com/mg-sharding created

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

$ k get mongodb -n demo                                                                                                                                             
NAME          VERSION    STATUS    AGE
mg-sharding   3.6.8-v1   Ready     2m9s

We are now ready to apply the MongoDBOpsRequest CR to upgrade this database.

Upgrade MongoDB Version

Here, we are going to upgrade MongoDB sharded database from 3.6.8 to 4.0.5.

Create MongoDBOpsRequest

In order to upgrade the sharded database, we have to create a MongoDBOpsRequest CR with your desired version that is supported by KubeDB. Below is the YAML of the MongoDBOpsRequest CR that we are going to create,

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-shard-upgrade
  namespace: demo
spec:
  type: Upgrade
  databaseRef:
    name: mg-sharding
  upgrade:
    targetVersion: 4.0.5-v3

Here,

spec.databaseRef.name specifies that we are performing operation on mg-sharding MongoDB database.
spec.type specifies that we are going to perform Upgrade on our database.
spec.upgrade.targetVersion specifies the expected version of the database 4.0.5.

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

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2021.04.16/docs/examples/mongodb/upgrading/mops-upgrade-shard.yaml
mongodbopsrequest.ops.kubedb.com/mops-shard-upgrade created

Verify MongoDB version upgraded successfully

If everything goes well, KubeDB Enterprise operator will update the image 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-shard-upgrade   Upgrade   Successful   2m31s

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 upgrade the database.

$ kubectl describe mongodbopsrequest -n demo mops-shard-upgrade

Name:         mops-shard-upgrade
Namespace:    demo
Labels:       <none>
Annotations:  API Version:  ops.kubedb.com/v1alpha1
Kind:         MongoDBOpsRequest
Metadata:
  Creation Timestamp:  2020-08-24T15:17:47Z
  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:upgrade:
          .:
          f:targetVersion:
    Manager:      kubectl
    Operation:    Update
    Time:         2020-08-24T15:17:47Z
    API Version:  ops.kubedb.com/v1alpha1
    Fields Type:  FieldsV1
    fieldsV1:
      f:metadata:
        f:finalizers:
      f:status:
        .:
        f:conditions:
        f:observedGeneration:
        f:phase:
    Manager:         kubedb-enterprise
    Operation:       Update
    Time:            2020-08-24T15:19:51Z
  Resource Version:  4830892
  Self Link:         /apis/ops.kubedb.com/v1alpha1/namespaces/demo/mongodbopsrequests/mops-shard-upgrade
  UID:               9683d8ed-35fa-4782-990d-0fb64160cd4a
Spec:
  Database Ref:
    Name:  mg-sharding
  Type:    Upgrade
  Upgrade:
    Target Version:  4.0.5-v3
Status:
  Conditions:
    Last Transition Time:  2020-08-24T15:17:47Z
    Message:               MongoDB ops request is starting to process
    Observed Generation:   1
    Reason:                UpgradingVersion
    Status:                True
    Type:                  UpgradingVersion
    Last Transition Time:  2020-08-24T15:17:48Z
    Message:               Successfully halted mongodb: mg-sharding
    Observed Generation:   1
    Reason:                HaltDatabase
    Status:                True
    Type:                  HaltDatabase
    Last Transition Time:  2020-08-24T15:17:50Z
    Message:               Succesfully stopped mongodb load balancer
    Observed Generation:   1
    Reason:                StoppingBalancer
    Status:                True
    Type:                  StoppingBalancer
    Last Transition Time:  2020-08-24T15:17:50Z
    Message:               Successfully updated statefulsets update strategy type
    Observed Generation:   1
    Reason:                UpdateStatefulSets
    Status:                True
    Type:                  UpdateStatefulSets
    Last Transition Time:  2020-08-24T15:18:15Z
    Message:               Successfully updated ConfigServer images
    Observed Generation:   1
    Reason:                UpdateConfigServerImage
    Status:                True
    Type:                  UpdateConfigServerImage
    Last Transition Time:  2020-08-24T15:19:25Z
    Message:               Successfully updated Shard images
    Observed Generation:   1
    Reason:                UpdateShardImage
    Status:                True
    Type:                  UpdateShardImage
    Last Transition Time:  2020-08-24T15:19:50Z
    Message:               Successfully updated Mongos images
    Observed Generation:   1
    Reason:                UpdateMongosImage
    Status:                True
    Type:                  UpdateMongosImage
    Last Transition Time:  2020-08-24T15:19:51Z
    Message:               Successfully Started mongodb load balancer
    Observed Generation:   1
    Reason:                StartingBalancer
    Status:                True
    Type:                  StartingBalancer
    Last Transition Time:  2020-08-24T15:19:51Z
    Message:               Succefully Resumed mongodb: mg-sharding
    Observed Generation:   1
    Reason:                ResumeDatabase
    Status:                True
    Type:                  ResumeDatabase
    Last Transition Time:  2020-08-24T15:19:51Z
    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            3m23s  KubeDB Enterprise Operator  Pausing Mongodb mg-sharding in Namespace demo
  Normal  HaltDatabase            3m23s  KubeDB Enterprise Operator  Successfully Halted Mongodb mg-sharding in Namespace demo
  Normal  StoppingBalancer         3m23s  KubeDB Enterprise Operator  Stopping Balancer
  Normal  StoppingBalancer         3m21s  KubeDB Enterprise Operator  Successfully Stopped Balancer
  Normal  Updating                 3m21s  KubeDB Enterprise Operator  Updating StatefulSets
  Normal  Updating                 3m21s  KubeDB Enterprise Operator  Successfully Updated StatefulSets
  Normal  UpdateConfigServerImage  3m21s  KubeDB Enterprise Operator  Updating ConfigServer Images
  Normal  UpdateConfigServerImage  3m11s  KubeDB Enterprise Operator  Successfully Updated Images of Pod mg-sharding-configsvr-1
  Normal  UpdateConfigServerImage  2m56s  KubeDB Enterprise Operator  Successfully Updated Images of Pod (master): mg-sharding-configsvr-0
  Normal  UpdateConfigServerImage  2m56s  KubeDB Enterprise Operator  Successfully Updated ConfigServer Images
  Normal  UpdateShardImage         2m56s  KubeDB Enterprise Operator  Updating Shard Images
  Normal  UpdateShardImage         2m36s  KubeDB Enterprise Operator  Successfully Updated Images of Pod mg-sharding-shard0-1
  Normal  UpdateShardImage         2m21s  KubeDB Enterprise Operator  Successfully Updated Images of Pod (master): mg-sharding-shard0-0
  Normal  UpdateShardImage         2m16s  KubeDB Enterprise Operator  Successfully Updated Images of Pod mg-sharding-shard1-1
  Normal  UpdateShardImage         2m6s   KubeDB Enterprise Operator  Successfully Updated Images of Pod (master): mg-sharding-shard1-0
  Normal  UpdateShardImage         116s   KubeDB Enterprise Operator  Successfully Updated Images of Pod mg-sharding-shard2-1
  Normal  UpdateShardImage         106s   KubeDB Enterprise Operator  Successfully Updated Images of Pod (master): mg-sharding-shard2-0
  Normal  UpdateShardImage         106s   KubeDB Enterprise Operator  Successfully Updated Shard Images
  Normal  UpdateMongosImage        106s   KubeDB Enterprise Operator  Updating Mongos Images
  Normal  UpdateMongosImage        86s    KubeDB Enterprise Operator  Successfully Updated Images of Pod (master): mg-sharding-mongos-0
  Normal  UpdateMongosImage        81s    KubeDB Enterprise Operator  Successfully Updated Images of Pod (master): mg-sharding-mongos-1
  Normal  UpdateMongosImage        81s    KubeDB Enterprise Operator  Successfully Updated Mongos Images
  Normal  Updating                 81s    KubeDB Enterprise Operator  Starting Balancer
  Normal  StartingBalancer         80s    KubeDB Enterprise Operator  Successfully Started Balancer
  Normal  ResumeDatabase           80s    KubeDB Enterprise Operator  Resuming MongoDB
  Normal  ResumeDatabase           80s    KubeDB Enterprise Operator  Successfully Started Balancer
  Normal  Successful               80s    KubeDB Enterprise Operator  Successfully Updated Database

Now, we are going to verify whether the MongoDB and the related StatefulSets of Mongos, Shard and ConfigeServer and their Pods have the new version image. Let’s check,

$ kubectl get mg -n demo mg-sharding -o=jsonpath='{.spec.version}{"\n"}'
4.0.5-v3

$ kubectl get sts -n demo mg-sharding-configsvr -o=jsonpath='{.spec.template.spec.containers[0].image}{"\n"}'
kubedb/mongo:4.0.5-v3

$ kubectl get sts -n demo mg-sharding-shard0 -o=jsonpath='{.spec.template.spec.containers[0].image}{"\n"}'
kubedb/mongo:4.0.5-v3

$ kubectl get sts -n demo mg-sharding-mongos -o=jsonpath='{.spec.template.spec.containers[0].image}{"\n"}'
kubedb/mongo:4.0.5-v3

$ kubectl get pods -n demo mg-sharding-configsvr-0 -o=jsonpath='{.spec.containers[0].image}{"\n"}'
kubedb/mongo:4.0.5-v3

$ kubectl get pods -n demo mg-sharding-shard0-0 -o=jsonpath='{.spec.containers[0].image}{"\n"}'
kubedb/mongo:4.0.5-v3

$ kubectl get pods -n demo mg-sharding-mongos-0 -o=jsonpath='{.spec.containers[0].image}{"\n"}'
kubedb/mongo:4.0.5-v3

You can see from above, our MongoDB sharded database has been updated with the new version. So, the upgrade process is successfully completed.

Cleaning Up

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

kubectl delete mg -n demo mg-sharding
kubectl delete mongodbopsrequest -n demo mops-shard-upgrade

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