# Migrate Kubernetes Objects Using Storage Version Migration

Migrate Kubernetes Objects Using Storage Version MigrationFEATURE STATE: Kubernetes v1.30 [alpha] (enabled by default: false)Kubernetes relies on API data being actively re-written, to support some maintenance activities related to at rest storage. Two prominent examples are the versioned schema of stored resources (that is, the preferred storage schema changing from v1 to v2 for a given resource) and encryption at rest (that is, rewriting stale data based on a change in how the data should be encrypted).Before you beginInstall kubectl.You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a cluster, you can create one by using minikube or you can use one of these Kubernetes playgrounds:iximiuz LabsKillercodaKodeKloudPlay with KubernetesYour Kubernetes server must be at or later than version v1.30.To check the version, enter kubectl version.Ensure that your cluster has the StorageVersionMigrator and InformerResourceVersion feature gates enabled. You will need control plane administrator access to make that change.Enable storage version migration REST api by setting runtime config storagemigration.k8s.io/v1alpha1 to true for the API server. For more information on how to do that, read enable or disable a Kubernetes API.Re-encrypt Kubernetes secrets using storage version migrationTo begin with, configure KMS provider to encrypt data at rest in etcd using following encryption configuration.kind: EncryptionConfiguration apiVersion: apiserver.config.k8s.io/v1 resources: - resources: - secrets providers: - aescbc: keys: - name: key1 secret: c2VjcmV0IGlzIHNlY3VyZQ== Make sure to enable automatic reload of encryption configuration file by setting --encryption-provider-config-automatic-reload to true.Create a Secret using kubectl.kubectl create secret generic my-secret --from-literal=key1=supersecret Verify the serialized data for that Secret object is prefixed with k8s:enc:aescbc:v1:key1.Update the encryption configuration file as follows to rotate the encryption key.kind: EncryptionConfiguration apiVersion: apiserver.config.k8s.io/v1 resources: - resources: - secrets providers: - aescbc: keys: - name: key2 secret: c2VjcmV0IGlzIHNlY3VyZSwgaXMgaXQ/ - aescbc: keys: - name: key1 secret: c2VjcmV0IGlzIHNlY3VyZQ== To ensure that previously created secret my-secret is re-encrypted with new key key2, you will use Storage Version Migration.Create a StorageVersionMigration manifest named migrate-secret.yaml as follows:kind: StorageVersionMigration apiVersion: storagemigration.k8s.io/v1alpha1 metadata: name: secrets-migration spec: resource: group: "" version: v1 resource: secrets Create the object using kubectl as follows:kubectl apply -f migrate-secret.yaml Monitor migration of Secrets by checking the .status of the StorageVersionMigration. A successful migration should have its Succeeded condition set to true. Get the StorageVersionMigration object as follows:kubectl get storageversionmigration.storagemigration.k8s.io/secrets-migration -o yaml The output is similar to:kind: StorageVersionMigration apiVersion: storagemigration.k8s.io/v1alpha1 metadata: name: secrets-migration uid: 628f6922-a9cb-4514-b076-12d3c178967c resourceVersion: "90" creationTimestamp: "2024-03-12T20:29:45Z" spec: resource: group: "" version: v1 resource: secrets status: conditions: - type: Running status: "False" lastUpdateTime: "2024-03-12T20:29:46Z" reason: StorageVersionMigrationInProgress - type: Succeeded status: "True" lastUpdateTime: "2024-03-12T20:29:46Z" reason: StorageVersionMigrationSucceeded resourceVersion: "84" Verify the stored secret is now prefixed with k8s:enc:aescbc:v1:key2.Update the preferred storage schema of a CRDConsider a scenario where a CustomResourceDefinition (CRD) is created to serve custom resources (CRs) and is set as the preferred storage schema. When it's time to introduce v2 of the CRD, it can be added for serving only with a conversion webhook. This enables a smoother transition where users can create CRs using either the v1 or v2 schema, with the webhook in place to perform the necessary schema conversion between them. Before setting v2 as the preferred storage schema version, it's important to ensure that all existing CRs stored as v1 are migrated to v2. This migration can be achieved through Storage Version Migration to migrate all CRs from v1 to v2.Create a manifest for the CRD, named test-crd.yaml, as follows:apiVersion: apiextensions.k8s.io/v1 kind: CustomResourceDefinition metadata: name: selfierequests.stable.example.com spec: group: stable.example.com names: plural: SelfieRequests singular: SelfieRequest kind: SelfieRequest listKind: SelfieRequestList scope: Namespaced versions: - name: v1 served: true storage: true schema: openAPIV3Schema: type: object properties: hostPort: type: string conversion: strategy: Webhook webhook: clientConfig: url: "https://127.0.0.1:9443/crdconvert" caBundle: <CABundle info> conversionReviewVersions: - v1 - v2 Create CRD using kubectl:kubectl apply -f test-crd.yaml Create a manifest for an example testcrd. Name the manifest cr1.yaml and use these contents:apiVersion: stable.example.com/v1 kind: SelfieRequest metadata: name: cr1 namespace: default Create CR using kubectl:kubectl apply -f cr1.yaml Verify that CR is written and stored as v1 by getting the object from etcd.ETCDCTL_API=3 etcdctl get /kubernetes.io/stable.example.com/testcrds/default/cr1 [...] | hexdump -C where [...] contains the additional arguments for connecting to the etcd server.Update the CRD test-crd.yaml to include v2 version for serving and storage and v1 as serving only, as follows:apiVersion: apiextensions.k8s.io/v1 kind: CustomResourceDefinition metadata: name: selfierequests.stable.example.com spec: group: stable.example.com names: plural: SelfieRequests singular: SelfieRequest kind: SelfieRequest listKind: SelfieRequestList scope: Namespaced versions: - name: v2 served: true storage: true schema: openAPIV3Schema: type: object properties: host: type: string port: type: string - name: v1 served: true storage: false schema: openAPIV3Schema: type: object properties: hostPort: type: string conversion: strategy: Webhook webhook: clientConfig: url: "https://127.0.0.1:9443/crdconvert" caBundle: <CABundle info> conversionReviewVersions: - v1 - v2 Update CRD using kubectl:kubectl apply -f test-crd.yaml Create CR resource file with name cr2.yaml as follows:apiVersion: stable.example.com/v2 kind: SelfieRequest metadata: name: cr2 namespace: default Create CR using kubectl:kubectl apply -f cr2.yaml Verify that CR is written and stored as v2 by getting the object from etcd.ETCDCTL_API=3 etcdctl get /kubernetes.io/stable.example.com/testcrds/default/cr2 [...] | hexdump -C where [...] contains the additional arguments for connecting to the etcd server.Create a StorageVersionMigration manifest named migrate-crd.yaml, with the contents as follows:kind: StorageVersionMigration apiVersion: storagemigration.k8s.io/v1alpha1 metadata: name: crdsvm spec: resource: group: stable.example.com version: v1 resource: SelfieRequest Create the object using kubectl as follows:kubectl apply -f migrate-crd.yaml Monitor migration of secrets using status. Successful migration should have Succeeded condition set to "True" in the status field. Get the migration resource as follows:kubectl get storageversionmigration.storagemigration.k8s.io/crdsvm -o yaml The output is similar to:kind: StorageVersionMigration apiVersion: storagemigration.k8s.io/v1alpha1 metadata: name: crdsvm uid: 13062fe4-32d7-47cc-9528-5067fa0c6ac8 resourceVersion: "111" creationTimestamp: "2024-03-12T22:40:01Z" spec: resource: group: stable.example.com version: v1 resource: testcrds status: conditions: - type: Running status: "False" lastUpdateTime: "2024-03-12T22:40:03Z" reason: StorageVersionMigrationInProgress - type: Succeeded status: "True" lastUpdateTime: "2024-03-12T22:40:03Z" reason: StorageVersionMigrationSucceeded resourceVersion: "106" Verify that previously created cr1 is now written and stored as v2 by getting the object from etcd.ETCDCTL_API=3 etcdctl get /kubernetes.io/stable.example.com/testcrds/default/cr1 [...] | hexdump -C where [...] contains the additional arguments for connecting to the etcd server.