Deploy a Replica Set

Supported with Cloud Manager and Ops Manager 4.0

You can use Kubernetes Operator to deploy MongoDB instances with Ops Manager version 4.0 or later and Cloud Manager. At any place in this guide that says Ops Manager, you can substitute Cloud Manager.

A replica set is a group of MongoDB deployments that maintain the same data set. Replica sets provide redundancy and high availability and are the basis for all production deployments.

To learn more about replica sets, see the Replication Introduction in the MongoDB manual.

Use this procedure to deploy a new replica set that Ops Manager manages. After deployment, use Ops Manager to manage the replica set, including such operations as adding, removing, and reconfiguring members.


To deploy a replica set using an object, you need to complete the following procedures:


Starting in MongoDB Enterprise Kubernetes Operator version 1.3.0, you can only have one MongoDB resource per project. To learn how to migrate your project to a single-cluster configuration, see Migrate to One Resource per Project (Required for Version 1.3.0).



Copy the highlighted section of this replica set resource.

Change the highlighted settings of this YAML file to match your desired replica set configuration.

kind: MongoDB
  name: <my-replica-set>
  namespace: <configMap.metadata.namespace>
             # Must match metadata.namespace in ConfigMap file
  members: 3
  version: 4.2.1
      name: <>
            # Must match in ConfigMap file
  credentials: <mycredentials>
  type: ReplicaSet
  persistent: true

Paste the copied example to create a new replica set resource.

Open your preferred text editor and paste the object specification into a new text file.


Change the highlighted settings to your preferred values.

Key Type Description Example string

Label for this Kubernetes replica set object.

See also

metadata.namespace string

Scope of object names. Kubernetes namespace where this MongoDB Kubernetes resource and other objects are created.

Using two different namespaces allows you to delete your standalone or all of the resources in the namespace without affecting your Kubernetes Operator.

See also

spec.members integer Number of members of the replica set. 3
spec.version string

Version of MongoDB that this replica set should run.

The format should be X.Y.Z for the Community edition and X.Y.Z-ent for the Enterprise edition.

To learn more about MongoDB versioning, see MongoDB Versioning in the MongoDB Manual.


Name of the ConfigMap with the Ops Manager connection configuration. The setting is an alias for this setting and can be used in its place.

Value must match namespace and name of ConfigMap

This value must match the value you provided for in your Ops Manager project ConfigMap.

If this MongoDB Kubernetes resource is in a different namespace than the project ConfigMap, you should set this value to the namespace and name of the ConfigMap in this format: <metadata.namespace>/<>

Operator manages changes to the ConfigMap

The Kubernetes Operator tracks any changes to the ConfigMap and reconciles the state of the MongoDB Kubernetes resource.

<myconfigmap> or <namespace>/<myconfigmap>
spec.credentials string

Name of the Kubernetes secret you created as Ops Manager API authentication credentials for the Kubernetes Operator to communicate with Ops Manager.

Value must use namespace and name of Secret

This value must match the value you provided for namespace and name for your Ops Manager Kubernetes Secret.

If this object is in a different namespace than the Secret, you should set this value to the namespace and name of the Secret in this format: <namespace>/<name>

Operator manages changes to the Secret

The Kubernetes Operator tracks any changes to the Secret and reconciles the state of the MongoDB Kubernetes resource.

<mycredentials> or <namespace>/<mycredentials>
spec.type string Type of MongoDB Kubernetes resource to create. ReplicaSet
spec.persistent string


Flag indicating if this MongoDB Kubernetes resource should use Persistent Volumes for storage. Persistent volumes are not deleted when the MongoDB Kubernetes resource is stopped or restarted.

If this value is true, then spec.podSpec.persistence.single is set to its default value of 16G.

To change your Persistent Volume Claims configuration, configure the following collections to meet your deployment requirements:


Your containers must have permissions to write to your Persistent Volume. The Kubernetes Operator sets fsGroup = 2000 in securityContext This makes Kubernetes try to fix write permissions for the Persistent Volume. If redeploying the deployment item does not fix issues with your Persistent Volumes, contact MongoDB Support.


If you do not use Persistent Volumes, the Disk Usage and Disk IOPS charts cannot be displayed in either the Processes tab on the Deployment page or in the Metrics page when reviewing the data for this deployment.


Add any additional accepted settings for a replica set deployment.

You can also add any of the following optional settings to the object specification file for a replica set deployment:


You must set spec.clusterName if your Kubernetes cluster has a default domain different from default cluster.local. If you neither use the default nor set this option, the Kubernetes Operator may not function as expected.


Save this replica set config file with a .yaml file extension.


Start your replica set deployment.

Invoke the following Kubernetes command to create your replica set:

kubectl apply -f <replica-set-conf>.yaml

Track the status of your replica set deployment.

To check the status of your MongoDB Kubernetes resource, invoke the following command:

kubectl get mdb <resource-name> -n <namespace> -o yaml -w

The -w flag means “watch”. With the “watch” flag set, the output refreshes immediately when something changes until the status phase achieves the Running state.

If the deployment fails, see Troubleshooting the Kubernetes Operator.