Backup and Restore StatefulSet App with Label

This topic describes how to use Velero to backup and restore a statefulset application with label.

Overview

This example demonstrates Velero backup and restore for a statefulset application with label selector. The CassandraDB app is used for demonstrating stateful backup and restore with Velero.

When restoring a 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 was 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, Velero, and Restic.

The application we are going to use is the CassandraDB statefulset app. Download the CassandraDB YAML files to a local known directory:

cassandra-statefulset.yaml
cassandra-storageclass.yaml
headless-cassandra-service.yaml

Create the Storage Class

Modify the storage class cassandra-storageclass.yaml:

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: demo-sts-sc
provisioner: kubernetes.io/vsphere-volume
parameters:
  diskformat: thin

Apply the storage class YAML file:

kubectl apply -f cassandra-storageclass.yaml

storageclass.storage.k8s.io/demo-sts-sc created

Verify the storage class:

kubectl get sc
NAME          PROVISIONER                    RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE

demo-sts-sc   kubernetes.io/vsphere-volume   Delete          Immediate           false                  3s

Deploy CassandraDB App

By default all the objects related to CassandraDB app have the same and common label: app=cassandra. Unlike the Guestbook app, you do not need to create a new label that is common to all Kubernetes objects for this app.

Create the namespace:

kubectl create ns cassandra

namespace/cassandra created

Create the service:

kubectl apply -f headless-cassandra-service.yaml -n cassandra

service/cassandra created

Deploy CassandraDB app:

kubectl apply -f cassandra-statefulset.yaml -n cassandra

statefulset.apps/cassandra created

Verify the CassandraDB app:

kubectl get all -n cassandra --show-labels
NAME              READY   STATUS    RESTARTS   AGE     LABELS
pod/cassandra-0   1/1     Running   0          2m24s   app=cassandra,controller-revision-hash=cassandra-559df6f5c,statefulset.kubernetes.io/pod-name=cassandra-0
pod/cassandra-1   1/1     Running   0          103s    app=cassandra,controller-revision-hash=cassandra-559df6f5c,statefulset.kubernetes.io/pod-name=cassandra-1
pod/cassandra-2   0/1     Running   0          29s     app=cassandra,controller-revision-hash=cassandra-559df6f5c,statefulset.kubernetes.io/pod-name=cassandra-2

NAME                TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE     LABELS
service/cassandra   ClusterIP   None         <none>        <none>    2m28s   app=cassandra

NAME                         READY   AGE     LABELS
statefulset.apps/cassandra   2/3     2m24s   app=cassandra

Verify PVC and PV:

kubectl get pvc,pv -n cassandra

Make sure CassandraDB instances are fully participating in the cluster:

kubectl exec -it cassandra-0 -n cassandra -- nodetool status

Datacenter: Demo-DataCenter
===========================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address     Load       Tokens       Owns (effective)  Host ID                               Rack
UN  172.16.1.2  104.41 KiB  32           68.0%             06df61ac-135c-406c-a1f1-d9937de38b9d  Demo-Rack
UN  172.16.1.3  94.96 KiB  32           75.7%             a49a5c78-85be-411f-a0b9-e28ff35fd918  Demo-Rack
UN  172.16.1.4  81.1 KiB   32           56.4%             85d124ee-0217-49e8-b56c-e13736038f02  Demo-Rack

Create and Populate a Database and Table in Cassandra

Create the DB:

kubectl exec -it cassandra-0 -n cassandra -- cqlsh

Connected to Demo-Cluster at 127.0.0.1:9042.
[cqlsh 5.0.1 | Cassandra 3.9 | CQL spec 3.4.2 | Native protocol v4]
Use HELP for help.

Create and populate table:

cqlsh> CREATE KEYSPACE demodb WITH REPLICATION = { ‘class’ : ‘SimpleStrategy’, ‘replication_factor’ : 3 }; cqlsh> use demodb; cqlsh:demodb> CREATE TABLE emp(emp_id int PRIMARY KEY, emp_name text, emp_city text, emp_sal varint,emp_phone varint); cqlsh:demodb> INSERT INTO emp (emp_id, emp_name, emp_city, emp_phone, emp_sal) VALUES (100, ‘Tom’, ‘Cork’, 999, 1000000); cqlsh:demodb> INSERT INTO emp (emp_id, emp_name, emp_city, emp_phone, emp_sal) VALUES (101, ‘Andrew’, ‘NY’, 1000, 1000000); cqlsh:demodb> INSERT INTO emp (emp_id, emp_name, emp_city, emp_phone, emp_sal) VALUES (102, ‘Lara’, ‘Paris’, 1001, 1000000); cqlsh:demodb> select * from emp;


Verify:

emp_id | emp_city | emp_name | emp_phone | emp_sal ——–+———-+———-+———–+——— 100 | Cork | Tom | 999 | 1000000 102 | Paris | Lara | 1001 | 1000000 101 | NY | Andrew | 1000 | 1000000

(3 rows)


Verify that the other Cassandra DB instances have the same information:

kubectl exec -it cassandra-1 -n cassandra – cqlsh

Connected to Demo-Cluster at 127.0.0.1:9042. [cqlsh 5.0.1 | Cassandra 3.9 | CQL spec 3.4.2 | Native protocol v4] Use HELP for help. cqlsh> use demodb; cqlsh:demodb> select * from emp;

(3 rows)

kubectl exec -it cassandra-2 -n cassandra – cqlsh

Connected to Demo-Cluster at 127.0.0.1:9042. [cqlsh 5.0.1 | Cassandra 3.9 | CQL spec 3.4.2 | Native protocol v4] Use HELP for help. cqlsh> use demodb; cqlsh:demodb> select * from emp;

(3 rows)


## <a id='cassandra-annotations'></a> Add Annotations

Add annotations for the stateful pods with the volume name `cassandra-data`.

kubectl get pod -n cassandra

NAME READY STATUS RESTARTS AGE cassandra-0 1/1 Running 0 19m cassandra-1 1/1 Running 0 19m cassandra-2 1/1 Running 0 17m


The pods `cassandra-0`, `cassandra-1` and `cassandra-2` must be annotated with `cassandra-data`.

kubectl -n cassandra annotate pod/cassandra-0 backup.velero.io/backup-volumes=cassandra-data pod/cassandra-0 annotated

kubectl -n cassandra annotate pod/cassandra-1 backup.velero.io/backup-volumes=cassandra-data pod/cassandra-1 annotated

kubectl -n cassandra annotate pod/cassandra-2 backup.velero.io/backup-volumes=cassandra-data pod/cassandra-2 annotated


Verify the annotations:

kubectl -n cassandra describe pod/cassandra-0 | grep Annotations Annotations: backup.velero.io/backup-volumes: cassandra-data

kubectl -n cassandra describe pod/cassandra-1 | grep Annotations Annotations: backup.velero.io/backup-volumes: cassandra-data

kubectl -n cassandra describe pod/cassandra-2 | grep Annotations Annotations: backup.velero.io/backup-volumes: cassandra-data


## <a id='cassandra-backup'></a> Backup the CassandraDB App Using Label

Perform the Velero backup:

velero backup create cassandra-label-backup –selector app=cassandra Backup request “cassandra-label-backup” submitted successfully.

Run velero backup describe cassandra-label-backup or velero backup logs cassandra-label-backup for more details.


Verify the backup:

velero backup get

NAME STATUS ERRORS WARNINGS CREATED EXPIRES STORAGE LOCATION SELECTOR cassandra-label-backup Completed 0 0 2020-07-29 09:48:49 -0700 PDT 29d default app=cassandra


View backup details:

velero backup describe cassandra-label-backup –details

Name: cassandra-label-backup Namespace: velero Labels: velero.io/storage-location=default Annotations: velero.io/source-cluster-k8s-gitversion=v1.17.8+vmware.1 velero.io/source-cluster-k8s-major-version=1 velero.io/source-cluster-k8s-minor-version=17

Phase: Completed

…

Velero-Native Snapshots:

Restic Backups: Completed: cassandra/cassandra-0: cassandra-data cassandra/cassandra-1: cassandra-data cassandra/cassandra-2: cassandra-data


Use Velero CRD commands to further verify the backup:

kubectl get crd

kubectl get backups.velero.io -n velero

NAME AGE cassandra-label-backup 96s

kubectl describe backups.velero.io cassandra-label-backup -n velero


## <a id='cassandra-restore'></a> Restore the CassandraDB App

Restore the CassandraDB app from the Velero backup. Note the following about the restore operation:

- Pod annotation is required to restore a Velero backup of a persistent volume (PV)
- The namespace 'cassandra' is automatically recreated during the restoration


Delete the namespace:

kubectl delete ns cassandra namespace “cassandra” deleted


Confirm that Cassandra resources are deleted:

kubectl get ns

NAME STATUS AGE default Active 21d kube-node-lease Active 21d kube-public Active 21d kube-system Active 21d pks-system Active 21d velero Active 7d18h

kubectl get pvc,pv –all-namespaces

No resources found


Verify that the storage class used by the application is still present:

kubectl get sc

NAME PROVISIONER RECLAIMPOLICY VOLUMEBINDINGMODE ALLOWVOLUMEEXPANSION AGE demo-sts-sc kubernetes.io/vsphere-volume Delete Immediate false 36m


Restore the CassandraDB app from the Velero backup:

velero restore create –from-backup cassandra-label-backup

Restore request “cassandra-label-backup-20200729095415” submitted successfully. Run velero restore describe cassandra-label-backup-20200729095415 or velero restore logs cassandra-label-backup-20200729095415 for more details.


Verify that the app is restored:

velero restore get

NAME BACKUP STATUS ERRORS WARNINGS CREATED SELECTOR cassandra-label-backup-20200729095415 cassandra-label-backup Completed 0 0 2020-07-29 09:54:15 -0700 PDT

velero restore describe cassandra-label-backup-20200729095415

Name: cassandra-label-backup-20200729095415 Namespace: velero Labels: Annotations:

Phase: Completed

Backup: cassandra-label-backup

Namespaces: Included: all namespaces found in the backup Excluded:

Resources: Included: * Excluded: nodes, events, events.events.k8s.io, backups.velero.io, restores.velero.io, resticrepositories.velero.io Cluster-scoped: auto

Namespace mappings:

Label selector:

Restore PVs: auto

Restic Restores (specify –details for more information): Completed: 3

kubectl get ns

NAME STATUS AGE cassandra Active 79s default Active 21d kube-node-lease Active 21d kube-public Active 21d kube-system Active 21d pks-system Active 21d velero Active 7d19h

kubectl get all -n cassandra –show-labels


Verify the persistent volume:

kubectl get pvc,pv -n cassandra –show-labels


Check the content of each Cassandra DB instance:

kubectl exec -it cassandra-0 -n cassandra – cqlsh

Connected to Demo-Cluster at 127.0.0.1:9042. [cqlsh 5.0.1 | Cassandra 3.9 | CQL spec 3.4.2 | Native protocol v4] Use HELP for help. cqlsh> use demodb; cqlsh:demodb> select * from emp;

kubectl exec -it cassandra-1 -n cassandra – cqlsh

Connected to Demo-Cluster at 127.0.0.1:9042. [cqlsh 5.0.1 | Cassandra 3.9 | CQL spec 3.4.2 | Native protocol v4] Use HELP for help. cqlsh> use demodb; cqlsh:demodb> select * from emp;

(3 rows)

kubectl exec -it cassandra-2 -n cassandra – cqlsh

Connected to Demo-Cluster at 127.0.0.1:9042. [cqlsh 5.0.1 | Cassandra 3.9 | CQL spec 3.4.2 | Native protocol v4] Use HELP for help. cqlsh> use demodb; cqlsh:demodb> select * from emp;

(3 rows)