CSI external-snapshotter
Status and Releases
Git Repository: https://github.com/kubernetes-csi/external-snapshotter
Status: GA v4.0.0+
CSI External-Snapshotter Sidecar
| Latest stable release | Branch | Min CSI Version | Max CSI Version | Container Image | Min K8s Version | Max K8s Version | Recommended K8s Version |
|---|---|---|---|---|---|---|---|
| external-snapshotter v4.0.0 | release-4.0 | v1.0.0 | - | k8s.gcr.io/sig-storage/csi-snapshotter:v4.0.0, | v1.20 | - | v1.20 |
| external-snapshotter v3.0.3 (beta) | release-3.0 | v1.0.0 | - | k8s.gcr.io/sig-storage/csi-snapshotter:v3.0.3, | v1.17 | - | v1.17 |
| external-snapshotter v2.1.4 (beta) | release-2.1 | v1.0.0 | - | quay.io/k8scsi/csi-snapshotter:v2.1.4 | v1.17 | - | v1.17 |
| external-snapshotter v1.2.2 (alpha) | release-1.2 | v1.0.0 | - | quay.io/k8scsi/csi-snapshotter:v1.2.2 | v1.13 | v1.16 | v1.14 |
| external-snapshotter v0.4.2 (alpha) | release-0.4 | v0.3.0 | v0.3.0 | quay.io/k8scsi/csi-snapshotter:v0.4.2 | v1.12 | v1.16 | v1.12 |
To use the snapshot beta and GA feature, a snapshot controller is also required. For more information, see this snapshot-controller page.
Snapshot Beta/GA
Description
Starting with the Beta version, the snapshot controller will be watching the Kubernetes API server for VolumeSnapshot and VolumeSnapshotContent CRD objects. The CSI external-snapshotter sidecar only watches the Kubernetes API server for VolumeSnapshotContent CRD objects. The CSI external-snapshotter sidecar is also responsible for calling the CSI RPCs CreateSnapshot, DeleteSnapshot, and ListSnapshots.
VolumeSnapshotClass Parameters
When provisioning a new volume snapshot, the CSI external-snapshotter sets the map<string, string> parameters field in the CSI CreateSnapshotRequest call to the key/values specified in the VolumeSnapshotClass it is handling.
The CSI external-snapshotter also reserves the parameter keys prefixed with csi.storage.k8s.io/. Any VolumeSnapshotClass keys prefixed with csi.storage.k8s.io/ are not passed to the CSI driver as an opaque parameter.
The following reserved VolumeSnapshotClass parameter keys trigger behavior in the CSI external-snapshotter:
csi.storage.k8s.io/snapshotter-secret-name(v1.0.1+)csi.storage.k8s.io/snapshotter-secret-namespace(v1.0.1+)csi.storage.k8s.io/snapshotter-list-secret-name(v2.1.0+)csi.storage.k8s.io/snapshotter-list-secret-namespace(v2.1.0+)
For more information on how secrets are handled see Secrets & Credentials.
VolumeSnapshot and VolumeSnapshotContent Parameters
The CSI external-snapshotter (v4.0.0+) introduces the --extra-create-metadata flag, which automatically sets the following map<string, string> parameters in the CSI CreateSnapshotRequest:
csi.storage.k8s.io/volumesnapshot/namecsi.storage.k8s.io/volumesnapshot/namespacecsi.storage.k8s.io/volumesnapshotcontent/name
These parameters are internally generated using the name and namespace of the source VolumeSnapshot and VolumeSnapshotContent.
For detailed snapshot beta design changes, see the design doc here.
For detailed information about volume snapshot and restore functionality, see Volume Snapshot & Restore.
Usage
CSI drivers that support provisioning volume snapshots and the ability to provision new volumes using those snapshots should use this sidecar container, and advertise the CSI CREATE_DELETE_SNAPSHOT controller capability.
For detailed information (binary parameters, RBAC rules, etc.), see https://github.com/kubernetes-csi/external-snapshotter/blob/release-2.0/README.md.
Deployment
The CSI external-snapshotter is deployed as a sidecar controller. See deployment section for more details.
For an example deployment, see this example which deploys external-snapshotter and external-provisioner with the Hostpath CSI driver.
Snapshot Alpha
Description
The CSI external-snapshotter is a sidecar container that watches the Kubernetes API server for VolumeSnapshot and VolumeSnapshotContent CRD objects.
The creation of a new VolumeSnapshot object referencing a SnapshotClass CRD object corresponding to this driver causes the sidecar container to trigger a CreateSnapshot operation against the specified CSI endpoint to provision a new snapshot. When a new snapshot is successfully provisioned, the sidecar container creates a Kubernetes VolumeSnapshotContent object to represent the new snapshot.
The deletion of a VolumeSnapshot object bound to a VolumeSnapshotContent corresponding to this driver with a delete deletion policy causes the sidecar container to trigger a DeleteSnapshot operation against the specified CSI endpoint to delete the snapshot. Once the snapshot is successfully deleted, the sidecar container also deletes the VolumeSnapshotContent object representing the snapshot.
Usage
CSI drivers that support provisioning volume snapshots and the ability to provision new volumes using those snapshots should use this sidecar container, and advertise the CSI CREATE_DELETE_SNAPSHOT controller capability.
For detailed information (binary parameters, RBAC rules, etc.), see https://github.com/kubernetes-csi/external-snapshotter/blob/release-1.2/README.md.
Deployment
The CSI external-snapshotter is deployed as a controller. See deployment section for more details.
For an example deployment, see this example which deploys external-snapshotter and external-provisioner with the Hostpath CSI driver.