> For the complete MongoDB documentation index, see www.mongodb.com/docs/llms.txt

# Migrate a Flex cluster to a Dedicated cluster

Atlas Kubernetes Operator doesn't support Atlas Infinite Database clusters in public preview. To learn which features Atlas Infinite Database supports in public preview, see [Atlas Infinite Database Edition](https://www.mongodb.com/docs/atlas/infinite/atlas-infinite-landing/). To learn more about preview features, see [Preview Features](https://www.mongodb.com/docs/preview-features/).

Atlas Kubernetes Operator supports migrating from a Flex cluster to a Dedicated cluster in place. This enables you to scale your database infrastructure directly from your Kubernetes environment.

## Prerequisites

Before you begin, you must have the following:

- An existing Flex cluster-tier `AtlasDeployment` managed by Atlas Kubernetes Operator.

- Permissions to modify the Flex cluster-tier `AtlasDeployment` resource in your Kubernetes cluster.

- Billing enabled for your Atlas project. Upgrading will result in charges to your Atlas account.

## Procedure

1. Find the Flex cluster configuration you want to upgrade.

   You can find your Flex cluster configuration in the `AtlasDeployment` resource managed by Atlas Kubernetes Operator.

   The following example shows a Flex cluster configuration on AWS in the `us-east-1` region.

   ```text
   # my-cluster.yaml
   apiVersion: atlas.mongodb.com/v1
   kind: AtlasDeployment
   metadata:
      name: my-flex-cluster
   spec:
      projectRef:
         name: my-atlas-project
      flexSpec:
         name: my-cluster
         providerSettings:
            backingProviderName: AWS
            regionName: US_EAST_1
   ```

2. Add the `spec.upgradeToDedicated` field and the full configuration for the target Dedicated cluster.

   Add the `spec.upgradeToDedicated` field to your `AtlasDeployment` resource. This field is a boolean flag that, when set to `true`, initiates an in-place upgrade from a Flex cluster to a Dedicated cluster.

   In the `spec.deploymentSpec` block, provide the full configuration for the target Dedicated cluster. This includes details such as the provider, region, instance size, and any other necessary parameters.

   Use the same name for your Dedicated cluster as your original Flex cluster.

   **Note:**

   If you use a different name for the Dedicated cluster, the migration fails.

   The following example shows how to modify the Flex cluster configuration to initiate the migration to a Dedicated cluster.

   ```text
   # my-cluster.yaml
   apiVersion: atlas.mongodb.com/v1
   kind: AtlasDeployment
   metadata:
     # The name MUST remain the same
     name: my-flex-cluster
   spec:
     projectRef:
       name: my-atlas-project

     # Add the upgrade flag
     upgradeToDedicated: true

     # Add the full configuration for the target Dedicated-cluster
     deploymentSpec:
         name: "my-cluster" # The name MUST remain the same
         clusterType: REPLICASET
         backupEnabled: true
         replicationSpecs:
            - regionConfigs:
               - providerName: AWS
                 regionName: US_EAST_1
                 priority: 7
                 electableSpecs:
                    instanceSize: M10
                    nodeCount: 3
   ```

3. Apply the change to your Kubernetes cluster.

   Use the `kubectl apply` command to apply the changes to your Kubernetes cluster.

   ```text
   kubectl apply -f my-cluster.yaml
   ```

4. Monitor the migration process.

   Atlas Kubernetes Operator immediately starts the migration process. You can monitor the progress using the `kubectl describe` command.

   ```text
   kubectl describe atlasdeployment my-flex-cluster
   ```

   Initially, the `DeploymentReady` condition appears as the following:

   ```text
   Status:
      Conditions:
        ...
        - Last Transition Time:  2025-06-18T10:00:00Z
          Message:             Cluster upgrade to dedicated instance initiated in Atlas...
          Reason:              FlexToDedicatedMigrationProgressing
          Status:              "False"
          Type:                DeploymentReady
   ```

   Once the migration is complete, the `DeploymentReady` condition updates to:

   ```text
   Status:
      Conditions:
         ...
         - Last Transition Time:  2025-06-18T10:15:00Z
           Message:             Cluster upgrade successful. You can now remove the 'upgradeToDedicated' flag from the spec.
           Status:              "True"
           Type:                DeploymentReady
   ```

   You also see a `Normal` event in the output after the upgrade completes. If the migration fails, the `DeploymentReady` condition shows an error message and the `Reason`. If you already migrated the cluster to Dedicated cluster, nothing changes.

5. Cleanup after migration.

   After the migration is complete, you can remove the `upgradeToDedicated` flag from your `AtlasDeployment` resource and apply it again. This step is optional but recommended to keep your configuration clean and prevent accidental re-triggering of the migration.

   The final `AtlasDeployment` resource looks like the following example:

   ```text
   # my-cluster.yaml
   apiVersion: atlas.mongodb.com/v1
   kind: AtlasDeployment
   metadata:
     name: my-flex-cluster
   spec:
     projectRef:
       name: my-atlas-project
     deploymentSpec:
         name: "my-cluster" # The name MUST remain the same
         clusterType: REPLICASET
         backupEnabled: true
         replicationSpecs:
            - regionConfigs:
               - providerName: AWS
                 regionName: US_EAST_1
                 priority: 7
                 electableSpecs:
                    instanceSize: M10
                    nodeCount: 3
   ```

6. Migration complete.

   You successfully migrated your Flex cluster to a Dedicated cluster. Your cluster is now a Dedicated cluster M10 instance. Manage it as a Dedicated cluster using Atlas Kubernetes Operator. Your application connection strings now point to the new Dedicated cluster.