This project is a POC that enables the end user to take a backup of a database instance in a cluster and later use that snapshot to recover the database instance when it restarts from scratch. VolumeSnapshotContent and VolumeSnapshot API resources are provided to create volume snapshots for users and administrators.

Prerequisites

1. This project is in development mode run in a local kubernetes cluster. For this purpose, I have used kind application to generate local cluster.
2. This project also relies extensively on VolumeSnapshot kind to actually do the heavy lifting of taking backkups and restoration.
3. Mysql database run as a POD and provisioned volume onto which data persists and intended to be backed up

Theory

In order to take snapshots following resource needs to be created in cluster:

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: csi-do-test-snapshot
spec:
  source:
    persistentVolumeClaimName: csi-do-test-pvc

In order to restore the snapshots, following persistent volume claim need to be generated:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: csi-do-test-pvc-restore
spec:
  dataSource:
    name: csi-do-test-snapshot
    kind: VolumeSnapshot
    apiGroup: snapshot.storage.k8s.io
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi

VolumeSnapshotContent is a snapshot taken from a volume in the cluster that has been provisioned by an administrator. It is a resource in the cluster just like a PersistentVolume is a cluster resource.

A VolumeSnapshot is a request for snapshot of a volume by a user. It is similar to a PersistentVolumeClaim.

Note: Installation of the CRDs is the responsibility of the Kubernetes distribution. Without the required CRDs present, the creation of a VolumeSnapshotClass fails.

Furthermore, the default storage provider in kind does not implement the CSI interface and thus is NOT capable of creating/handling volume snapshots. For that, you must first deploy a CSI driver.

You can use the following CSI snapshot CRDs and drivers from https://github.com/kubernetes-csi/external-snapshotter/tree/release-3.0

Steps

• Deply the custom CRD to inform the cluster about the incoming CRs
• Create a cr to take user input, the controller will detect it and it will spin up a cr for snapshot
• To restore, we need create a pv where source has to be kept as snapshot, and then deployment has to modified and run again
• For restore we can do it in the same crd using boolean for now.