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The backup-controller is a Kubernetes operator that uses the CSI Volume Snapshot API to manage backups of your Persistent Volumes.

The backup-controller works by allowing you to specify a backup frequency, retention period, and whether or not you want to automatically set the PersistentVolumeClaim to use the latest snapshot when it is created. This ensures a painless and error free workflow for managing backups of stateful services in Kubernetes.

Installation

To install, deploy the manifest:

kubectl apply -f deploy.yaml

Usage

To use, set the following annotations on any PersistentVolumeClaim that should be backed up:

  • snapshot-frequency: if set, snapshots will automatically be taken at the interval specified (as a duration: 1d6h30m).
  • snapshot-retention: if set, snapshots will automatically be deleted when they are older than the specified expiration (as a duration: 1d6h30m).
  • restore-latest: if present, when the PersistentVolumeClaim is created, the operator will automatically set the dataSource to the latest snapshot.

An example PersistentVolumeClaim:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: csi-do-test-pvc
  annotations:
    restore-latest: "true"
    snapshot-frequency: 2m
    snapshot-retention: 10m
spec:
  storageClassName: do-block-storage
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi

The backup-controller will create a snapshot of the volume every two minutes. Any snapshots older than ten minutes will be deleted.

To see snapshots, list them with kubectl:

➜  ~ kubectl get volumesnapshots
NAME                                                   AGE
csi-do-test-pvc-31fac8c7-e8b6-449c-90da-b0e8f0cd8f6d   6m
csi-do-test-pvc-3749454d-5f45-405d-b1fc-94d080f85f59   2m
csi-do-test-pvc-4d18af84-5d68-4f69-8996-f1e6fefbb724   8m
csi-do-test-pvc-e86b3ae4-2700-4b81-8e3f-30832f7076b9   4m
csi-do-test-pvc-eb9d99af-95cc-4fc2-a0af-70fe29b02729   6s
➜  ~

Because restore-latest is set, if the PersistentVolumeClaim is deleted and recreated it will automatically have the dataSource field set to the most recently created snapshot:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: csi-do-test-pvc
  annotations:
    restore-latest: "true"
    snapshot-frequency: 2m
    snapshot-retention: 10m
spec:
  storageClassName: do-block-storage
  accessModes:
    - ReadWriteOnce
  dataSource:
    name: csi-do-test-pvc-eb9d99af-95cc-4fc2-a0af-70fe29b02729
    kind: VolumeSnapshot
    apiGroup: snapshot.storage.k8s.io
  resources:
    requests:
      storage: 5Gi

This feature ensures that your PersistentVolumeClaims can always be restored from the most recent snapshot without any modification to the manifest (e.g., the latest snapshot id does not have to be present).

Without backup-controller, in order to restore a PersistentVolumeClaim to a snapshot it must first be deleted and then be recreated with the dataSource field set to the VolumeSnapshot to restore from. backup-controller ensures portable configuration by automatically setting the dataSource on PersistentVolumeClaims to the most recent backup using an Mutating Admission Controller.

Combined with Flux any PersistentVolumeClaim that is deleted will automatically be restored from the most recent snapshot.

To fully ensure that your snapshots are safe, also ensure that your VolumeSnapshots and VolumeSnapshotContents are backed up.