Create group snapshots using VolumeSnapshots in OCP IBM Cloud

Summary and Key concepts

Summary:

This article provides a guide on creating group snapshots of Portworx volumes in Kubernetes using annotations or Portworx volume group IDs. It explains prerequisites such as installing Stork and details how to create group snapshots for PVCs that match certain annotations or belong to a specific namespace. The article outlines how to manage, track, and delete group snapshots using Kubernetes commands like oc or kubectl. An example is provided that shows how to take group snapshots of all PVCs in a namespace and how to monitor the status of these snapshots.

Kubernetes Concepts:

• PersistentVolumeClaim (PVC): A request for storage in Kubernetes, which can be snapshotted as part of a group.
• Annotations: Metadata used for selecting PVCs and managing group snapshots.
• Namespace: Used to divide resources in Kubernetes, which can also be used to group PVCs for snapshots.

Portworx Concepts:

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

• VolumeSnapshot: Represents a snapshot of a Portworx volume in Kubernetes.

• Volume Group Snapshot: A feature that allows the creation of snapshots for multiple PVCs at once using annotations or group IDs.

This document will show you how to create group snapshots of Portworx volumes and how you can clone those snapshots to use them in pods.

Pre-requisites

Installing Stork

This requires that you already have Stork installed and running on your Kubernetes cluster. If you fetched the Portworx specs from the Portworx spec generator in Portworx Central and used the default options, Stork is already installed.

Creating group snapshots

To take group snapshots, one either specifies annotations that will match PVCs for the group or a Portworx volume group ID.

The group snapshot method supports the following annotations:

• portworx/snapshot-type: Indicates the type of snapshot. For group snapshots, the value should be local.
• portworx.selector/<key>: <value>: When this annotation is provided, Portworx will select all PVCs with labels <key>:<value> and create a group snapshot. Example: portworx.selector/stack: wordpress.
• portworx.selector/group-id: Group ID of the Portworx volumes if they were created using the --group parameter. Portworx will select all volumes that match this group ID and create a group snapshot.

If both annotations and group ID are specified above, all PVCs that match annotations and group ID will be snapshotted.

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

Examples

Creating snapshots of all PVCs that match certain annotations

In below example, we are taking a group snapshot that will snap all PVCs in the default namespace and that have labels tier: prod and type: db. The prefix portworx.selector/ before the annotation keys indiciate these are annotations that Stork will process to select PVCs.

Portworx will quiesce I/O on all volumes before triggering their snapshots.

apiVersion: volumesnapshot.external-storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: mysql-snapshot
  namespace: default
  annotations:
    portworx/snapshot-type: local
    portworx.selector/tier: prod
    portworx.selector/type: db
spec:
  persistentVolumeClaimName: mysql-data

persistentVolumeClaimName in the above spec can be a name of any single PVC that will get matched using the selector or the group ID.

Once you apply the above object you can check the status of the snapshots using the oc get volumesnapshot.volumesnapshot.external-storage.k8s.io/ command with the name of your snapshot appended:

oc get volumesnapshot.volumesnapshot.external-storage.k8s.io/mysql-snapshot

NAME                                              AGE
volumesnapshots/mysql-data-1-779368893912016693   14s
volumesnapshots/mysql-data-2-314922951056863611   14s
volumesnapshots/mysql-snapshot                    16s

oc get volumesnapshotdatas

NAME                                                                                            AGE
volumesnapshotdatas/k8s-snapshotdata-xxxxxxxx-xxxx-xxxx-xxxx-5a6317d9d914                    14s
volumesnapshotdatas/k8s-snapshotdata-xxxxxxxx-xxxx-xxxx-xxxx-5a6317d9d914                    14s
volumesnapshotdatas/k8s-snapshotdata-xxxxxxxx-xxxx-xxxx-xxxx-5a6317d9d914                    14s

Above we can see that creation of mysql-snapshot created 2 more volumesnapshots mysql-data-1-779368893912016693 and mysql-data-2-314922951056863611. Each of these would correspond to the PVCs that matched the annotations/group-id specified in the mysql-snapshot volumesnapshot.

The creation of the volumesnapshotdatas object indicates that the snapshot has been created. If you describe the volumesnapshotdatas object you can see the Portworx Snapshot IDs and the PVCs for which the snapshot was created.

oc describe volumesnapshotdatas

Name:         k8s-snapshotdata-xxxxxxxx-xxxx-xxxx-xxxx-5a6317d9d914
Namespace:
Labels:       <none>
Annotations:  <none>
API Version:  volumesnapshot.external-storage.k8s.io/v1
Kind:         VolumeSnapshotData
Metadata:
  Cluster Name:
  Creation Timestamp:  2018-04-29T00:19:55Z
  Resource Version:    1501612
  Self Link:           /apis/volumesnapshot.external-storage.k8s.io/v1/k8s-snapshotdata-xxxxxxxx-xxxx-xxxx-xxxx-5a6317d9d914
  UID:                 xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
Spec:
  Persistent Volume Ref:
    Kind:  PersistentVolume
    Name:  pvc-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
  Portworx Volume:
    Snapshot Data:  k8s-snapshotdata-xxxxxxxx-xxxx-xxxx-xxxx-5a6317d9d914,k8s-snapshotdata-xxxxxxxx-xxxx-xxxx-xxxx-5a6317d9d914
    Snapshot Id:    779368893912016693,314922951056863611
    Snapshot Type:  local
  Volume Snapshot Ref:
    Kind:  VolumeSnapshot
    Name:  default/mysql-snapshot
Status:
  Conditions:
    Last Transition Time:  <nil>
    Message:               Snapshot created successfully and it is ready
    Reason:
    Status:                True
    Type:                  Ready
  Creation Timestamp:      <nil>
Events:                    <none>

Name:         k8s-snapshotdata-xxxxxxxx-xxxx-xxxx-xxxx-5a6317d9d914
Namespace:
Labels:       namespace=default
Annotations:  <none>
API Version:  volumesnapshot.external-storage.k8s.io/v1
Kind:         VolumeSnapshotData
Metadata:
  Cluster Name:
  Creation Timestamp:  2018-04-29T00:19:55Z
  Resource Version:    1501608
  Self Link:           /apis/volumesnapshot.external-storage.k8s.io/v1/k8s-snapshotdata-xxxxxxxx-xxxx-xxxx-xxxx-5a6317d9d914
  UID:                 xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
Spec:
  Persistent Volume Ref:  <nil>
  Portworx Volume:
    Snapshot Id:    779368893912016693
    Snapshot Type:  local
  Volume Snapshot Ref:
    Kind:  VolumeSnapshot
    Name:  default/mysql-data-1-779368893912016693
Status:
  Conditions:
    Last Transition Time:  <nil>
    Message:               Snapshot created successfully and it is ready
    Reason:
    Status:                True
    Type:                  Ready
  Creation Timestamp:      <nil>
Events:                    <none>

Name:         k8s-snapshotdata-xxxxxxxx-xxxx-xxxx-xxxx-5a6317d9d914
Namespace:
Labels:       namespace=default
Annotations:  <none>
API Version:  volumesnapshot.external-storage.k8s.io/v1
Kind:         VolumeSnapshotData
Metadata:
  Cluster Name:
  Creation Timestamp:  2018-04-29T00:19:55Z
  Resource Version:    1501610
  Self Link:           /apis/volumesnapshot.external-storage.k8s.io/v1/k8s-snapshotdata-xxxxxxxx-xxxx-xxxx-xxxx-5a6317d9d914
  UID:                 xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
Spec:
  Persistent Volume Ref:  <nil>
  Portworx Volume:
    Snapshot Id:    314922951056863611
    Snapshot Type:  local
  Volume Snapshot Ref:
    Kind:  VolumeSnapshot
    Name:  default/mysql-data-2-314922951056863611
Status:
  Conditions:
    Last Transition Time:  <nil>
    Message:               Snapshot created successfully and it is ready
    Reason:
    Status:                True
    Type:                  Ready
  Creation Timestamp:      <nil>
Events:                    <none>

Creating snapshots of all PVCs in a namespace

Below spec will take snapshots of all PVCs in the dev namespace.

Portworx will quiesce I/O on all volumes before triggering their snapshots.

apiVersion: volumesnapshot.external-storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: mysql-snapshot-all-dev
  namespace: dev
  annotations:
    portworx/snapshot-type: local
    portworx.selector/namespace: dev
spec:
  persistentVolumeClaimName: mysql-data

Deleting group snapshots

To delete group snapshots, you need to delete the VolumeSnapshot that was used to create the group snapshots. Stork will delete all other volumesnapshots that were created for this group snapshot.