Working with snapshots

Managed Service for Kubernetes supports snapshots, which are a point-in-time copy of a PersistentVolume. For more information about snapshots, see the Kubernetes documentation.

To create a snapshot and then restore it:

1. Prepare a test environment.
2. Create a snapshot.
3. Restore objects from the snapshot.

If you no longer need the resources you created, delete them.

Getting startedGetting started

1. Create Kubernetes resources:

   Manually

   Terraform

   1. Create security groups for the Managed Service for Kubernetes cluster and its node groups.

      Warning

      The configuration of security groups determines the performance and availability of the cluster and the services and applications running in it.

   2. Create a Managed Service for Kubernetes cluster and a node group in any suitable configuration. When creating them, specify the security groups prepared earlier.

   1. If you do not have Terraform yet, install it.

   2. Get the authentication credentials. You can add them to environment variables or specify them later in the provider configuration file.

   3. Configure and initialize a provider. There is no need to create a provider configuration file manually, you can download it.

   4. Place the configuration file in a separate working directory and specify the parameter values. If you did not add the authentication credentials to environment variables, specify them in the configuration file.

   5. Download the k8s-cluster.tf cluster configuration file to the same working directory. The file describes:

      • Network.

      • Subnet.

      • Managed Service for Kubernetes cluster.

      • Service account required to create the Managed Service for Kubernetes cluster and node group.

      • Security groups which contain rules required for the Managed Service for Kubernetes cluster and its node groups.

        Warning

        The configuration of security groups determines the performance and availability of the cluster and the services and applications running in it.

   6. Specify the folder ID in the configuration file.

   7. Check that the Terraform configuration files are correct using this command:

      terraform validate
      

      If there are any errors in the configuration files, Terraform will point them out.

   8. Create the required infrastructure:

      1. Run the command to view planned changes:

         terraform plan
         

         If the resource configuration descriptions are correct, the terminal will display a list of the resources to modify and their parameters. This is a test step. No resources are updated.

      2. If you are happy with the planned changes, apply them:

         1. Run the command:

            terraform apply
            

         2. Confirm the update of resources.

         3. Wait for the operation to complete.

      All the required resources will be created in the specified folder. You can check resource availability and their settings in the management console.

2. Install kubectl and configure it to work with the created cluster.

Prepare a test environmentPrepare a test environment

To test snapshots, a PersistentVolumeClaim and a pod to simulate the workload will be created.

1. Create the 01-pvc.yaml file with the PersistentVolumeClaim manifest:

   ---
   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: pvc-dynamic
   spec:
     accessModes:
       - ReadWriteOnce
     storageClassName: yc-network-hdd
     resources:
       requests:
         storage: 5Gi
   

2. Create a PersistentVolumeClaim:

   kubectl apply -f 01-pvc.yaml
   

3. Make sure the PersistentVolumeClaim has been created and its status is Pending:

   kubectl get pvc pvc-dynamic
   

4. Create the 02-pod.yaml file with the pod-source pod manifest:

   ---
   apiVersion: v1
   kind: Pod
   metadata:
     name: pod-source
   spec:
     containers:
       - name: app
         image: ubuntu
         command: ["/bin/sh"]
         args:
           ["-c", "while true; do echo $(date -u) >> /data/out.txt; sleep 5; done"]
         volumeMounts:
           - name: persistent-storage
             mountPath: /data
     volumes:
       - name: persistent-storage
         persistentVolumeClaim:
           claimName: pvc-dynamic
   

   The pod container will write the current date and time to the /data/out.txt file.

5. Create a pod named pod-source:

   kubectl apply -f 02-pod.yaml
   

6. Make sure the pod has entered the Running state:

   kubectl get pod pod-source
   

7. Make sure the date and time are written to /data/out.txt. For this, run the following command on the pod:

   kubectl exec pod-source -- tail /data/out.txt
   

   Result:

   Thu Feb 3 04:55:21 UTC 2022
   Thu Feb 3 04:55:26 UTC 2022
   ...
   

Create a snapshotCreate a snapshot

1. Create the 03-snapshot.yaml file with the snapshot manifest:

   ---
   apiVersion: snapshot.storage.k8s.io/v1
   kind: VolumeSnapshot
   metadata:
     name: new-snapshot-test
   spec:
     volumeSnapshotClassName: yc-csi-snapclass
     source:
       persistentVolumeClaimName: pvc-dynamic
   

2. Create a snapshot:

   kubectl apply -f 03-snapshot.yaml
   

3. Check that the snapshot has been created:

   kubectl get volumesnapshots.snapshot.storage.k8s.io
   

4. Make sure the VolumeSnapshotContent has been created:

   kubectl get volumesnapshotcontents.snapshot.storage.k8s.io
   

Restore objects from the snapshotRestore objects from the snapshot

When restoring objects from the snapshot, the following items are created in the cluster:

• PersistentVolumeClaim object named pvc-restore.
• Pod named pod-restore with entries in /data/out.txt.

To restore the snapshot:

1. Create the 04-restore-snapshot.yaml file with the new PersistentVolumeClaim manifest:

   ---
   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: pvc-restore
   spec:
     storageClassName: yc-network-hdd
     dataSource:
       name: new-snapshot-test
       kind: VolumeSnapshot
       apiGroup: snapshot.storage.k8s.io
     accessModes:
       - ReadWriteOnce
     resources:
       requests:
         storage: 10Gi
   

   Tip

   You can resize the new PersistentVolumeClaim. To do this, specify its new size in the spec.resources.requests.storage setting value.

2. Create a new PersistentVolumeClaim:

   kubectl apply -f 04-restore-snapshot.yaml
   

3. Make sure the PersistentVolumeClaim has been created and its status is Pending:

   kubectl get pvc pvc-restore
   

4. Create the 05-pod-restore.yaml file with a manifest for the new pod, i.e., pod-restore:

   ---
   apiVersion: v1
   kind: Pod
   metadata:
     name: pod-restore
   spec:
     containers:
       - name: app-restore
         image: ubuntu
         command: ["/bin/sh"]
         args: ["-c", "while true; do sleep 5; done"]
         volumeMounts:
           - name: persistent-storage-r
             mountPath: /data
     volumes:
       - name: persistent-storage-r
         persistentVolumeClaim:
           claimName: pvc-restore
   

   The new pod container will not perform any actions with /data/out.txt.

5. Create a pod named pod-restore:

   kubectl apply -f 05-pod-restore.yaml
   

6. Make sure the pod has entered the Running state:

   kubectl get pod pod-restore
   

7. Make sure the new PersistentVolumeClaim has entered the Bound state:

   kubectl get pvc pvc-restore
   

8. Make sure the /data/out.txt file on the new pod contains records that the pod-source pod container added to the file before creating the snapshot:

   kubectl exec pod-restore -- tail /data/out.txt
   

   Result:

   Thu Feb 3 04:55:21 UTC 2022
   Thu Feb 3 04:55:26 UTC 2022
   ...
   

Delete the resources you createdDelete the resources you created

Delete the resources you no longer need to avoid paying for them:

1. Delete the Managed Service for Kubernetes cluster:

   Manually

   Terraform

   Delete the Managed Service for Kubernetes cluster.

   1. In the terminal window, go to the directory containing the infrastructure plan.

      Warning

      Make sure the directory has no Terraform manifests with the resources you want to keep. Terraform deletes all resources that were created using the manifests in the current directory.

   2. Delete resources:

      1. Run this command:

         terraform destroy
         

      2. Confirm deleting the resources and wait for the operation to complete.

      All the resources described in the Terraform manifests will be deleted.

2. Delete the cluster's public static IP address if you had reserved one.

3. Delete the disk snapshot.