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
cassandrais 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)
