Snapshot single PVCs in OCP IBM Cloud

Summary and Key concepts

Summary:

This article provides instructions on how to create snapshots of PVCs backed by Portworx volumes in Kubernetes. It explains how to create snapshots within a single namespace and across multiple namespaces using Kubernetes manifests. The guide covers checking snapshot status with oc and storkctl commands, and includes an example of taking snapshots in one namespace and restoring them in another. The article also outlines using annotations to manage cross-namespace snapshot restoration and provides YAML examples for creating PVCs from snapshots.

Kubernetes Concepts:

• PersistentVolumeClaim (PVC): Used to request storage in Kubernetes, and can be snapshotted and restored.
• Annotations: Attach metadata to Kubernetes objects, like defining which namespaces can restore snapshots.
• Namespace: Used to isolate resources and manage PVC snapshots across different namespaces.

Portworx Concepts:

• Stork: A Kubernetes extension used for managing storage operations such as snapshots.

• VolumeSnapshot: Represents a snapshot of a Portworx volume for backup and restoration purposes.

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 oc:

   oc get -n jenkins volumesnapshot

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

   oc get -n jenkins volumesnapshotdatas

   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:

   oc 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