Create a Backup via CSI
Backups in Longhorn are objects in an off-cluster backupstore, and the endpoint to access the backupstore is the backup target. For more information, see this section.
To programmatically create backups, you can use the generic Kubernetes CSI snapshot mechanism. To learn more about the CSI snapshot mechanism, click here.
Prerequisite: CSI snapshot support needs to be enabled on your cluster. If your kubernetes distribution does not provide the kubernetes snapshot controller as well as the snapshot related custom resource definitions, you need to manually deploy them. For more information, see Enable CSI Snapshot Support.
To create a backup using the CSI mechanism, create a Kubernetes VolumeSnapshot
object via kubectl
. An example is here.
Result:
A backup is created. The VolumeSnapshot
object creation leads to the creation of a VolumeSnapshotContent
Kubernetes object.
The VolumeSnapshotContent
refers to a Longhorn backup in its VolumeSnapshotContent.snapshotHandle
field with the name bs://backup-volume/backup-name
.
When the VolumeSnapshot object is created with kubectl, the VolumeSnapshot.uuid
field is used to identify a Longhorn snapshot and the associated VolumeSnapshotContent
object.
This creates a new Longhorn snapshot named snapshot-uuid
.
Then a backup of that snapshot is initiated, and the CSI request returns.
Afterwards a VolumeSnapshotContent
object named snapcontent-uuid
is created.
The CSI snapshotter sidecar periodically queries the Longhorn CSI plugin to evaluate the backup status.
Once the backup is completed, the VolumeSnapshotContent.readyToUse
flag is set to true.
To see the backup, click Backup in the top navigation bar and navigate to the backup-volume mentioned in the VolumeSnapshotContent.snapshotHandle
.
For information on how to restore a volume via a VolumeSnapshot
object,
refer to this page.
An example VolumeSnapshot
object is below. The source
needs to point to the PVC of the Longhorn volume for which a backup should be created.
The volumeSnapshotClassName
field points to a VolumeSnapshotClass
.
We create a default class named longhorn
, which uses Delete
as its deletionPolicy
.
apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshot
metadata:
name: test-snapshot-pvc
spec:
volumeSnapshotClassName: longhorn
source:
persistentVolumeClaimName: test-vol
If you want the associated backup for a volume to be retained when the VolumeSnapshot
is deleted, create a new VolumeSnapshotClass
with Retain
set as the deletionPolicy
.
For more information about snapshot classes, see the kubernetes documentation for VolumeSnapshotClasses.
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