Snapshot Restore API¶
snapshot.kubevirt.io API Group defines resources for snapshotting and restoring KubeVirt
KubeVirt leverages the
VolumeSnapshot functionality of Kubernetes CSI drivers for capturing persistent
VirtualMachine state. So, you should make sure that your
PersistentVolumeClaims backed by a
StorageClass that supports
VolumeSnapshots and a
VolumeSnapshotClass is properly configured for that
kubectl get volumesnapshotclass
Make sure the
provisioner property of your
StorageClass matches the
driver property of the
Even if you have no
VolumeSnapshotClasses in your cluster,
VirtualMachineSnapshots are not totally useless. They will still backup your
Snapshot Feature Gate¶
Snapshot/Restore support must be enabled in the feature gates to be supported. The
field in the KubeVirt CR must be expanded by adding the
Snapshot to it.
Snapshot a VirtualMachine¶
Snapshotting a virtualMachine is supported for online and offline vms.
When snapshotting a running vm the controller will check for qemu guest agent in the vm. If the agent exists it will freeze the vm filesystems before taking the snapshot and unfreeze after the snapshot. It is recommended to take online snapshots with the guest agent for a better snapshot, if not present a best effort snapshot will be taken.
Note To check if your vm has a qemu-guest-agent check for 'AgentConnected' in the vm status.
There will be an indication in the vmSnapshot status if the snapshot was taken online and with or without guest agent participation.
Note Currently online vm snapshot is not supported with hotplugged disks, in this case the vm has to be turned off in order to take the snapshot (or all hotplugged disks unplugged).
To snapshot a
larry, apply the following yaml.
apiVersion: snapshot.kubevirt.io/v1alpha1 kind: VirtualMachineSnapshot metadata: name: snap-larry spec: source: apiGroup: kubevirt.io kind: VirtualMachine name: larry
To wait for a snapshot to complete, execute:
kubectl wait vmsnapshot snap-larry --for condition=Ready
You can check the vmSnapshot phase in the vmSnapshot status. It can be one of the following: * InProgress * Succeeded * Failed.
The vmSnapshot has a default deadline of 5 minutes. If the vmSnapshot has not succeessfully completed before the deadline, it will be marked as Failed. The VM will be unfrozen and the created snapshot content will be cleaned up if necessary. The vmSnapshot object will remain in Failed state until deleted by the user. To change the default deadline add 'FailureDeadline' to the VirtualMachineSnapshot spec with a new value. The allowed format is a duration string which is a possibly signed sequence of decimal numbers, each with optional fraction and a unit suffix, such as "300ms", "-1.5h" or "2h45m"
apiVersion: snapshot.kubevirt.io/v1alpha1 kind: VirtualMachineSnapshot metadata: name: snap-larry spec: source: apiGroup: kubevirt.io kind: VirtualMachine name: larry failureDeadline: 1m
In order to set an infinite deadline you can set it to 0 (not recommended).
Restoring a VirtualMachine¶
To restore the
snap-larry, apply the following yaml.
apiVersion: snapshot.kubevirt.io/v1alpha1 kind: VirtualMachineRestore metadata: name: restore-larry spec: target: apiGroup: kubevirt.io kind: VirtualMachine name: larry virtualMachineSnapshotName: snap-larry
To wait for a restore to complete, execute:
kubectl wait vmrestore restore-larry --for condition=Ready
VirtualMachineSnapshots (and their corresponding
VirtualMachineSnapshotContents) around as long as you may want to restore from them again.
Feel free to delete
larry-restore as it is not needed once the restore is complete.