Back Up and Restore StatefulSet App with Label

This topic describes how to use Velero to back up and restore a StatefulSet application with label.

Overview

This example demonstrates Velero back up and restore for a StatefulSet application with label selector. The Cassandra database app is used for demonstrating stateful back up 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 Cassandra database StatefulSet app. Download the Cassandra Database 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 Cassandra Database App

By default all the objects related to Cassandra database 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 Cassandra database app:

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

statefulset.apps/cassandra created

Verify the Cassandra database 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 Cassandra database 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:

• Cassandra DB instance 1

  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;
  
   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)
  

• Cassandra DB instance 2

  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;
  
   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)
  

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

Back Up the Cassandra Database App Using Label

Perform the Velero back up:

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: <none included>

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

Use Velero Kubernetes CustomResourceDefinition (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

Restore the Cassandra Database App

Restore the Cassandra database 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 Cassandra database 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   <none>

velero restore describe cassandra-label-backup-20200729095415

Name:         cassandra-label-backup-20200729095415
Namespace:    velero
Labels:       <none>
Annotations:  <none>

Phase:  Completed

Backup:  cassandra-label-backup

Namespaces:
  Included:  all namespaces found in the backup
  Excluded:  <none>

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

Namespace mappings:  <none>

Label selector:  <none>

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:

• Cassandra DB instance 0

  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;
  
   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
  

• Cassandra DB instance 1

  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;
  
   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)
  

• Cassandra DB instance 2

  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;
  
   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)