Snapshot single PVCs in Tanzu

Summary and Key concepts

Summary:

This article demonstrates how to create and manage snapshots of Persistent Volume Claims (PVCs) backed by Portworx volumes in Kubernetes. It provides steps to create snapshots within a single namespace and across multiple namespaces. The guide shows how to manage snapshots using Kubernetes manifests, annotations, and the storkctl command-line tool. Additionally, it includes an example of creating a PVC from a snapshot in another namespace and offers methods to verify snapshots using both kubectl and storkctl commands. The article also explains how to specify cross-namespace snapshot restoration through annotations.

Kubernetes Concepts:

• PersistentVolumeClaim (PVC): A request for storage in Kubernetes, can be snapshotted and restored.
• Namespace: Used for isolating resources such as PVCs and snapshots within Kubernetes clusters.
• StorageClass: Defines how storage is dynamically provisioned for PVCs.
• Annotations: Attach metadata to objects, such as defining snapshot sources and cross-namespace restoration.

Portworx Concepts:

• Stork: A storage orchestration tool that manages snapshots, backups, and cross-namespace restoration in Kubernetes.

• VolumeSnapshot: A snapshot of a Portworx volume, allowing for point-in-time data restoration.

• storkctl: A CLI tool for managing Portworx storage operations like snapshots and backups.

This document will show you how to create a snapshot of a PVC backed by a Portworx volume.

Creating snapshot within a single namespace

1. If you have a PVC called jenkins-home-jenkins-master-0, in the jenkins namespace, you can create a snapshot for that PVC by using the following spec:

   apiVersion: volumesnapshot.external-storage.k8s.io/v1
   kind: VolumeSnapshot
   metadata:
     name: jenkins-home-jenkins-master-0
     namespace: jenkins
   spec:
     persistentVolumeClaimName: jenkins-home-jenkins-master-0

2. Once you apply the above object you can check the status of the snapshots using kubectl:

   kubectl get volumesnapshot.volumesnapshot.external-storage.k8s.io -n jenkins

   NAME                                                      AGE
   jenkins-jobs-jenkins-master-0-snapshot-2019-03-20-snap1   6m

   kubectl get volumesnapshot.volumesnapshotdatas.external-storage.k8s.io -n jenkins 

   NAME                                                       AGE
   k8s-volume-snapshot-xxxxxxxx-xxxx-xxxx-xxxx-0242ac110002   8m

3. The creation of the volumesnapshotdatas object indicates that the snapshot has been created. If you describe the volumesnapshotdatas object you can see the Portworx Volume Snapshot ID and the PVC for which the snapshot was created:

kubectl describe volumesnapshotdatas

Name:         k8s-volume-snapshot-xxxxxxxx-xxxx-xxxx-xxxx-0242ac110002
Namespace:
Labels:       <none>
Annotations:  <none>
API Version:  volumesnapshot.external-storage.k8s.io/v1
Kind:         VolumeSnapshotData
Metadata:
  Creation Timestamp:  2019-03-20T22:22:37Z
  Generation:          1
  Resource Version:    56596513
  Self Link:           /apis/volumesnapshot.external-storage.k8s.io/v1/volumesnapshotdatas/k8s-volume-snapshot-xxxxxxxx-xxxx-xxxx-xxxx-0242ac110002
  UID:                 xxxxxxxx-xxxx-xxxx-xxxx-0cc47ab5f9a2
Spec:
  Persistent Volume Ref:
    Kind:  PersistentVolume
    Name:  pvc-xxxxxxxx-xxxx-xxxx-xxxx-0cc47ab5f9a2
  Portworx Volume:
    Snapshot Id:    411710013297550893
    Snapshot Type:  local
  Volume Snapshot Ref:
    Kind:  VolumeSnapshot
     Name:  jenkins/jenkins-jobs-jenkins-master-0-snapshot-2019-03-20-snap1-xxxxxxxx-xxxx-xxxx-xxxx-0cc47ab5f9a2
Status:
  Conditions:
    Last Transition Time:  2019-03-20T22:22:37Z
    Message:               Snapshot created successfully and it is ready
    Reason:
    Status:                True
    Type:                  Ready
  Creation Timestamp:      <nil>
Events:                    <none>

4. You can use the storkctl command to verify that the snapshot was created successfully:

   storkctl -n jenkins get snap

   NAME                                                      PVC                             STATUS    CREATED               COMPLETED             TYPE
   jenkins-jobs-jenkins-master-0-snapshot-2019-03-20-snap1   jenkins-jobs-jenkins-master-0   Ready     20 Mar 19 15:22 PDT   20 Mar 19 15:22 PDT   local

For details about how you can restore a snapshot to a new PVC or the original PVC, see the Restore snapshots section.

Creating snapshots across namespaces

When creating snapshots, you can provide comma separated regexes with stork.libopenstorage.org/snapshot-restore-namespaces annotation to specify which namespaces the snapshot can be restored to. When creating PVC from snapshots, if a snapshot exists in another namespace, the snapshot namespace should be specified with stork.libopenstorage.org/snapshot-source-namespace annotation.

Let's take an example where we have 2 namespaces dev and prod. We will create a PVC and snapshot in the dev namespace and then create a PVC in the prod namespace from the snapshot.

1. Create the namespaces

   apiVersion: v1
   kind: Namespace
   metadata:
     name: dev
     labels:
       name: dev
   ---
   apiVersion: v1
   kind: Namespace
   metadata:
     name: prod
     labels:
       name: prod

2. Create the PVC

   kind: PersistentVolumeClaim
   apiVersion: v1
   metadata:
     name: mysql-data
     namespace: dev
     annotations:
       volume.beta.kubernetes.io/storage-class: px-mysql-sc
   spec:
     accessModes:
       - ReadWriteOnce
     resources:
       requests:
         storage: 2Gi
   ---
   kind: StorageClass
   apiVersion: storage.k8s.io/v1
   metadata:
     name: px-mysql-sc
   provisioner: pxd.portworx.com
   parameters:
     repl: "2"

3. Create the snapshot

   apiVersion: volumesnapshot.external-storage.k8s.io/v1
   kind: VolumeSnapshot
   metadata:
     name: mysql-snapshot
     namespace: dev
     annotations:
       stork.libopenstorage.org/snapshot-restore-namespaces: "prod"
   spec:
     persistentVolumeClaimName: mysql-data
   

4. Create a PVC in a different namespace from the snapshot

   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: mysql-clone
     namespace: prod
     annotations:
       snapshot.alpha.kubernetes.io/snapshot: mysql-snapshot
       stork.libopenstorage.org/snapshot-source-namespace: dev
   spec:
     accessModes:
       - ReadWriteOnce
     storageClassName: stork-snapshot-sc
     resources:
       requests:
         storage: 2Gi