controllers

csi-volumegroupsnapshotter Controller

The csi-volumegroupsnapshotter controller processes reconcile requests for VolumeGroupSnapshot events. This README describes the basic controller logic.

Reconcile Logic for VolumeGroupSnapshot Create Event

Reconciliation steps:

1. Find all PVC instances with volume-group label as defined in pvcLabel attribute in volume group snapshot

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: pvol0
  namespace: helmtest-vxflexos
  labels:
    volume-group: volumeGroup1
spec:
  accessModes:
  - ReadWriteOnce
  volumeMode: Filesystem
  resources:
    requests:
      storage: 8Gi
  storageClassName: vxflexos

1. Get volumeHandle for all corresponding PersistentVolume instances for this set of PVCs.
2. Call CreateVolumeGroupSnapshot() CSI API extension method of CSI driver with list of volume handles and volume group snapshot name.
3. Once driver responds with list of Snapshot objects create VolumeSnapshot and VolumeSnapshotContent instances for group members in Kubernetes. As a result, VolumeSnapshot and VolumeSnapshotContent instances are created for each snapshot in the group. To associate VolumeSnapshot instances with parent group, these objects are labeled with VolumeGroupSnapshot name.
4. Update status of VolumeGroupSnapshot to set groupID, creationTime and list of VolumeSnapshot member names.

Reconcile Logic for VolumeGroupSnapshot Delete Event

Reconciliation steps:

1. Process member VolumeSnapshot instances based on the value of Deletion Policy in volumesnapshotclass that vgs specifies. For Delete call Kubernetes API to delete each VolumeSnapshot instance. Kubernetes will also delete the corresponding VolumeSnapshotContent instance. For Retain keep VolumeSnapshot instances.

CSI Extension for Volume Group Snapshot Operations in Drivers

The CSI extension API is defined here under volumeGroupSnapshot.