README.md

Data Backup and restore in SAP BTP, Kyma runtime

Overview

This sample demonstrates how to take volume snapshots (backups) for a stateful application deployed on SAP BTP, Kyma runtime.

As a next step, it demonstrates restoring the data from a volume snapshot.

Prerequisites

• SAP BTP, Kyma runtime instance
• Kubernetes tooling

Set up the app

• Create a dev namespace

  kubectl create namespace dev
  
  kubectl label namespaces dev istio-injection=enabled

• Create a stateful application. For this demo, we will deploy a busybox based StatefulSet that has a PersistentVolumeClaim attached.

  kubectl -n dev apply -f k8s/statefulset.yaml

• Wait for the stateful application to get up and running

  kubectl -n dev get po -l app=example-stateful-app

• Let's store some data in the stateful app

  kubectl -n dev exec example-stateful-app-0 -c example-stateful-app -- /bin/sh -c "echo 'my crucial data' >> /data/1.txt"

• Verify that data is there

  kubectl -n dev exec example-stateful-app-0 -c example-stateful-app -- /bin/sh -c "cat /data/1.txt"

Take Snapshot

• Create a snapshot class. The driver specified driver: disk.csi.azure.com depends upon the hyperscaler used. Please refer to this Kyma open source documentation, Gardener Section to provide the appropriate value.

  kubectl apply -f k8s/snapshot-class.yaml

• Take a snapshot of the persistent volume

  kubectl -n dev apply -f k8s/snapshot.yaml

• Wait until the volume snapshot status is Ready to use.

  kubectl -n dev get volumesnapshot

Simulate a disaster

Let's simulate a disaster scenario.

• Remove the app as well as the persistent volume claim.

  kubectl -n dev delete -f k8s/statefulset.yaml
  
  kubectl -n dev delete pvc storage-example-stateful-app-0

Recovery

Lets deploy the app and also recover the data using the snapshot.

We will restore the statefuleset and provide a datasource as the snapshot previously created.

```yaml
volumeClaimTemplates:
- metadata:
    name: pvc-restored
    spec:
    accessModes:
    - ReadWriteOnce
    dataSource:
        kind: VolumeSnapshot
        name: snapshot
        apiGroup: snapshot.storage.k8s.io
    resources:
        requests:
        storage: 1Gi
```

• Restore the data and application

  kubectl -n dev apply -f k8s/restored-statefulset.yaml

• Wait for the pod to be up and running

  kubectl -n dev get po -l app=example-stateful-app

• Verify that the data is restored

  kubectl -n dev exec example-stateful-app-0 -c example-stateful-app -- /bin/sh -c "cat /data/1.txt"