Kubernetes v1.34: Moving Volume Group Snapshots to v1beta2

By Xing Yang (VMware by Broadcom) |

Volume group snapshots were introduced as an Alpha feature with the Kubernetes 1.27 release and moved to Beta in the Kubernetes 1.32 release. The recent release of Kubernetes v1.34 moved that support to a second beta. The support for volume group snapshots relies on a set of extension APIs for group snapshots. These APIs allow users to take crash consistent snapshots for a set of volumes. Behind the scenes, Kubernetes uses a label selector to group multiple PersistentVolumeClaims for snapshotting. A key aim is to allow you restore that set of snapshots to new volumes and recover your workload based on a crash consistent recovery point.

This new feature is only supported for CSI volume drivers.

What's new in Beta 2?

While testing the beta version, we encountered an issue where the restoreSize field is not set for individual VolumeSnapshotContents and VolumeSnapshots if CSI driver does not implement the ListSnapshots RPC call. We evaluated various options here and decided to make this change releasing a new beta for the API.

Specifically, a VolumeSnapshotInfo struct is added in v1beta2, it contains information for an individual volume snapshot that is a member of a volume group snapshot. VolumeSnapshotInfoList, a list of VolumeSnapshotInfo, is added to VolumeGroupSnapshotContentStatus, replacing VolumeSnapshotHandlePairList. VolumeSnapshotInfoList is a list of snapshot information returned by the CSI driver to identify snapshots on the storage system. VolumeSnapshotInfoList is populated by the csi-snapshotter sidecar based on the CSI CreateVolumeGroupSnapshotResponse returned by the CSI driver's CreateVolumeGroupSnapshot call.

The existing v1beta1 API objects will be converted to the new v1beta2 API objects by a conversion webhook.

What’s next?

Depending on feedback and adoption, the Kubernetes project plans to push the volume group snapshot implementation to general availability (GA) in a future release.

How can I learn more?

How do I get involved?

This project, like all of Kubernetes, is the result of hard work by many contributors from diverse backgrounds working together. On behalf of SIG Storage, I would like to offer a huge thank you to the contributors who stepped up these last few quarters to help the project reach beta:

For those interested in getting involved with the design and development of CSI or any part of the Kubernetes Storage system, join the Kubernetes Storage Special Interest Group (SIG). We always welcome new contributors.

We also hold regular Data Protection Working Group meetings. New attendees are welcome to join our discussions.