Back Up and Restore Stateful App with Namespace (CSI Edition)

This topic describes how to use Velero to back up and restore a stateful application with namespace using the Container Storage Interface (CSI).

Overview

This topic describes how to use Velero to back up and restore a stateful application with namespace using the Container Storage Interface (CSI) instead of the proprietary VMware Cloud Provider (vCP).

To test Velero back up and restore for stateful applications, use the Guestbook application with a persistent volume.

When restoring the stateful application using Velero, the Storage Class that was used by the PVC in the application must be present on the Kubernetes cluster. If the PVC is using the default storage class, then the default storage class must also be present prior to initiating the restore operation with Velero.

Prerequisites

Install and configure Minio and Velero.

Download the Guestbook app YAML files to a local known directory:

redis-leader-deployment.yaml
redis-leader-service.yaml
redis-follower-deployment.yaml
redis-follower-service.yaml
frontend-deployment.yaml
frontend-service.yaml

Create CSI Storage Class

Create the following storage class named guestbook-storageclass.yaml. Note that the generic CSI provisioner is used (csi.vsphere.vmware.com), as opposed to the proprietary vCP provisioner (kubernetes.io/vsphere-volume).

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: guestbook-sc-csi
  annotations:
    storageclass.kubernetes.io/is-default-class: "true"
provisioner: csi.vsphere.vmware.com
parameters:
  datastoreurl: "ds:///vmfs/volumes/vsan:52d8eb4842dbf493-41523be9cd4ff7b7/"

Apply the YAML file:

kubectl apply -f 0-guestbook-storageclass.yaml

storageclass.storage.k8s.io/guestbook-sc-csi created

Verify:

kubectl get sc

NAME                         PROVISIONER              RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
guestbook-sc-csi (default)   csi.vsphere.vmware.com   Delete          Immediate           false                  4s

Deploy Guestbook App

Create Guestbook namespace:

kubectl create ns guestbook-csi

namespace/guestbook-csi created

Deploy the Guestbook app:

kubectl apply -f . -n guestbook-csi

storageclass.storage.k8s.io/guestbook-sc-csi unchanged
persistentvolumeclaim/redis-leader-claim created
persistentvolumeclaim/redis-follower-claim created
service/redis-leader created
deployment.apps/redis-leader created
service/redis-follower created
deployment.apps/redis-follower created
service/frontend created
deployment.apps/frontend created

Verify:

kubectl get all -n guestbook-csi

kubectl get pvc,pv -n guestbook-csi

Access the Guestbook app at http://10.199.41.14/.

Guestbook App

Add many messages so they can be stored in the PV.

Guestbook App

Back Up the Guestbook App Using Namespace

Because this app is stateful, you need to add annotations for the stateful pods with the volume name.

Get the volume names:

kubectl get pod -n guestbook-csi

The volume name is redis-leader-data for pod redis-leader-64fb8775bf-wg5tk.

The volume name is redis-follower-data for pod redis-follower-779b6d8f79-mqcrx.

Annotate the pods:

kubectl -n guestbook-csi annotate pod redis-leader-64fb8775bf-wg5tk backup.velero.io/backup-volumes=redis-leader-data
pod/redis-leader-64fb8775bf-wg5tk annotated

kubectl -n guestbook-csi annotate pod redis-follower-779b6d8f79-mqcrx backup.velero.io/backup-volumes=redis-follower-data
pod/redis-follower-779b6d8f79-mqcrx annotated

Verify:

kubectl -n guestbook-csi describe pod redis-leader-64fb8775bf-wg5tk | grep Annotations
Annotations:  backup.velero.io/backup-volumes: redis-leader-data

kubectl -n guestbook-csi describe pod redis-follower-779b6d8f79-mqcrx | grep Annotations
Annotations:  backup.velero.io/backup-volumes: redis-follower-data

Perform the Velero back up:

velero backup create guestbook-csi-backup --include-namespaces guestbook-csi

Backup request "guestbook-csi-backup" submitted successfully.
Run `velero backup describe guestbook-csi-backup` or `velero backup logs guestbook-csi-backup` for more details.

Verify the backup that was created.

velero backup get

NAME                   STATUS      ERRORS   WARNINGS   CREATED                         EXPIRES   STORAGE LOCATION   SELECTOR
guestbook-csi-backup   Completed   0        0          2020-07-30 13:36:13 -0700 PDT   29d       default            <none>

Verify backup details:

velero backup describe guestbook-csi-backup --details

Use Velero Kubernetes CustomResourceDefinition (CRD) commands to further verify:

kubectl get backups.velero.io -n velero

NAME                    AGE
guestbook-csi-backup    4m58s

kubectl describe backups.velero.io guestbook-csi-backup -n velero

Restore the Guestbook App

To test the restoration of the Guestbook app, delete it.

Delete the namespace:

kubectl delete ns guestbook-csi

namespace "guestbook-csi" deleted

Verify namespace deletion:

kubectl get ns

kubectl get pvc,pv --all-namespaces

Make sure the storage class used by the application is still present:

kubectl get sc

NAME                         PROVISIONER              RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
guestbook-sc-csi (default)   csi.vsphere.vmware.com   Delete          Immediate           false                  11m

Restore the app:

velero restore create --from-backup guestbook-csi-backup

Restore request "guestbook-csi-backup-20200730134254" submitted successfully.
Run `velero restore describe guestbook-csi-backup-20200730134254` or `velero restore logs guestbook-csi-backup-20200730134254` for more details.

Verify that the app is restored:

velero restore describe guestbook-csi-backup-20200730134254

Run the following commands to verify:

velero restore get

NAME                                  BACKUP                 STATUS      ERRORS   WARNINGS   CREATED                         SELECTOR
guestbook-csi-backup-20200730134254   guestbook-csi-backup   Completed   0        0          2020-07-30 13:42:54 -0700 PDT   <none>

kubectl get ns

NAME              STATUS   AGE
default           Active   22d
guestbook-csi     Active   71s
kube-node-lease   Active   22d
kube-public       Active   22d
kube-system       Active   22d
pks-system        Active   22d
velero            Active   8d

kubectl get all -n guestbook-csi

kubectl get pvc,pv -n guestbook-csi

Access the Guestbook app at http://10.199.41.10/.

Guestbook App

Conclusions

The Velero restore might not show the saved messages. This is not a Velero issue. The Guestbook app is using some kind of RAM cache for the messages so if those messages are not flushed into disk, the data is not available in the PV.

Key takeaways from the restore operation for this scenario:

Pod annotation is still required for Velero to back up a PV.
The namespace guestbook-csi was automatically re-created.
The Kubernetes service LB IP has changed, from 10.199.41.14 to .16.