Backup & Restore Stateful Applications on AKS using Velero

A reference implementation for using Velero in AKS cluster to backup and restore persistent volumes using CSI storage drivers.

Overview

Velero provides capabilities to back up and restore your Kubernetes cluster resources and persistent volumes.

Velero lets you:

• Take backups of your cluster and restore in case of loss.
• Migrate cluster resources to other clusters.
• Replicate your production cluster to development and testing clusters.

Velero consists of:

• A server that runs on your cluster
• A command-line client that runs locally

Intalling Velero on AKS cluster

The Velero backup tool consists of a client installed on your local computer and a server that runs in your Kubernetes cluster. To begin, we’ll install the local Velero client from here. Add Velero client to PATH.

Verify that you can run the velero client by executing the binary:

velero help

Output:
Velero is a tool for managing disaster recovery, specifically for Kubernetes
cluster resources. It provides a simple, configurable, and operationally robust
way to back up your application state and associated data.

Prepare Credentials File

Edit the credentials with subscription and storage account used for backup.

$ cat << EOF  > ./credentials-velero
AZURE_SUBSCRIPTION_ID='<your-azure-subscription>'
AZURE_TENANT_ID='<azure-tenant-id>'
AZURE_CLIENT_ID='<azure-client-id>'
AZURE_CLIENT_SECRET='<azure-client-secret>'
AZURE_RESOURCE_GROUP='<managed-aks-resource-group (starts with MC_)>'
AZURE_CLOUD_NAME=AzurePublicCloud
EOF

Installing Velero

A Velero installation consists of a number of Kubernetes objects that all work together to create, schedule, and manage backups. The velero executable that you just downloaded can generate and install these objects for you. The velero install command will perform the preliminary set-up steps to get your cluster ready for backups. Specifically, it will:

• Create a velero Namespace.
• Add the velero Service Account.
• Configure role-based access control (RBAC) rules to grant permissions to the velero Service Account.
• Install Custom Resource Definitions (CRDs) for the Velero-specific resources: Backup, Schedule, Restore, Config.
• Register Velero Plugins to manage Block snapshots and Spaces storage.

Run the velero install command with some non-default configuration options.

$ velero install \
--image velero:v1.4.0 \
--provider azure \
--plugins velero-plugin-for-microsoft-azure:v1.1.0 \
--velero-pod-cpu-limit 1 \
--velero-pod-mem-limit 1Gi \
--bucket <blob-container-name> \
--secret-file ./credentials-velero \
--backup-location-config resourceGroup=<storage-account-resourcegroup>,storageAccount=<storage-account-name>,subscriptionId=<storage-account-subscription-id> \
--snapshot-location-config apiTimeout=5m,resourceGroup=<snapshot-resourcegroup>,subscriptionId=<snapshot-subscription-id>

Testing Backup and Restore Procedure

Now that we’ve successfully installed and configured Velero, we can create a test azure-vote deployment, with a Persistent Volume and Service. Once the Deployment is running we will run through a backup and restore drill to ensure that Velero is configured and working properly.

Deploy Voting App

We will be deploying a sample Voting App for testing Velero backup/restore capabilities. Voting App consists of two microservices:

1. voting-frontend - A python based web app
2. voting-backend - A redis store with persistent volume

Create a namespace azure-vote where the application will be deployed.

$ kubectl create namespace azure-vote

Create a TLS secret using certificate created from previous step in azure-vote namespace. Kubernetes Ingress Controller will be configured to use this certificate for securing endpoint using TLS.

kubectl create secret tls ingress-tls-cert -n azure-vote --key /path-to-key-file.key --cert /path-to-key-file.crt

Apply the manifest examples/azure-vote-deploy.yaml to deploy Voting App in azure-vote namespace.

$ kubectl apply -f examples/azure-vote-deploy.yaml

OUTPUT:

deployment.apps/voting-backend created
service/voting-backend created
deployment.apps/voting-frontend created
service/voting-frontend created

Check whether Voting App got deployed successfully.

$ kubectl get all -n azure-vote

OUTPUT:

NAME                                  READY   STATUS    RESTARTS   AGE
pod/voting-backend-854dd7cd8d-2qn7m   1/1    Running   0          11s
pod/voting-frontend-d4657b7bc-86xkx   1/1     Running   0          11s

NAME                      TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
service/voting-backend    ClusterIP   10.251.103.214   <none>        6379/TCP   11s
service/voting-frontend   ClusterIP   10.251.93.142    <none>        80/TCP     11s

NAME                              READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/voting-backend    1/1     1            1           12s
deployment.apps/voting-frontend   0/1     1            0           11s

NAME                                        DESIRED   CURRENT   READY   AGE
replicaset.apps/voting-backend-854dd7cd8d   1         1         1       12s
replicaset.apps/voting-frontend-d4657b7bc   1         1         0       11s

Verify whether the app is loading in the brower by entering host configured above.

Chrome: https:///

Back up persistent volumes of Voting App using Velero

We’ll create a backup called azure-vote-bkp using the velero command line client. --selector option identifies resources by label. --include-resources option limits backup of specified resource types. In our example, we will backup pv (persistenvolume) and pvc (persistentvolumeclaim) resources only.

$ velero backup create azure-vote-bkp --include-resources pvc,pv --selector app=azure-vote

Check whether backup was successful. Add --details for more information.

$ velero backup describe azure-vote-bkp

Output
Name:         azure-vote-bkp
Namespace:    velero
Labels:       velero.io/storage-location=default
Annotations:  velero.io/source-cluster-k8s-gitversion=v1.16.10
              velero.io/source-cluster-k8s-major-version=1
              velero.io/source-cluster-k8s-minor-version=16

Phase:  Completed

Errors:    0
Warnings:  0

Namespaces:
  Included:  *
  Excluded:  <none>

Resources:
  Included:        pvc, pv
  Excluded:        <none>
  Cluster-scoped:  auto

Label selector:  app=azure-vote

Storage Location:  default

Velero-Native Snapshot PVs:  auto

TTL:  720h0m0s

Hooks:  <none>

Backup Format Version:  1

Started:    2020-08-18 17:25:10 +0530 IST
Completed:  2020-08-18 17:25:22 +0530 IST

Expiration:  2020-09-17 17:25:10 +0530 IST

Total items to be backed up:  2
Items backed up:              2

Velero-Native Snapshots:  1 of 1 snapshots completed successfully (specify --details for more information)

We can now test the restore procedure.

Delete Voting App

Let’s first delete the azure-vote Namespace to simulate a failure. This will delete all resources in the Namespace, including the Persistent Volume:

$ kubectl delete namespace azure-vote

Verify that you can no longer access Voting App from the browser, and that the azure-vote resources are no longer running:

kubectl get all -n azure-vote

OUTPUT:

No resources found in azure-vote namespace.

We can now perform the restore procedure, using the velero client.

Restore Voting App using velero

Create the namespace azure-vote where the application will be restored.

$ kubectl create namespace azure-vote

Create a Velero Restore object from the azure-vote-bkp Backup object.

velero restore create --from-backup azure-vote-bkp

Verify whether persistent volume resources have been restored in azure-vote namespace.

kubectl get pvc,pv --namespace azure-vote

OUTPUT:

NAME                                    STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS      AGE
persistentvolumeclaim/azure-vote-back   Bound    pvc-c9b439a8-1962-4a23-a139-66a5114cb029   1Gi        RWO            managed-premium   109s

NAME                                                        CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                        STORAGECLASS      REASON   AGE
persistentvolume/pvc-c9b439a8-1962-4a23-a139-66a5114cb029   1Gi        RWO            Delete           Bound    azure-vote/azure-vote-back   managed-premium            109s

Redeploy Voting App

Deploy rest of the Voting App resources using kubectl apply:

$ kubectl apply -f examples/azure-vote-deploy.yaml

Check status of the pods.

$ kubectl get pods -n azure-vote

OUTPUT:

NAME                               READY   STATUS    RESTARTS   AGE
azure-vote-back-5b944bc5d5-l554m   1/1     Running   0          46s
azure-vote-front-d8ff6fccd-jbrf2   1/1     Running   0          45s

Verify whether the app is loading in brower by entering host url.

Chrome: https://

Cluster Level Backup/Restoration

To perform cluster level backup/restore, both cluster should have similar backup-location & snapshot-location. Also, The default sync interval is set as 1 minute. You could change the interval with the flag --backup-sync-period when creating a backup location.

While performing backup, after default sync-time, backup objects will be visible in both the clusters when running velero get backup command. Post which, restoration can be initiated. However, Restore & Schedule objects will be visible under respective clusters only, as they are cluster specific features.

Cleanup

Uninstall Voting App

kubectl delete namespace azure-vote

Uninstall Velero

The following commands will remove all resources created by velero install:

kubectl delete namespace/velero clusterrolebinding/velero
kubectl delete crds -l component=velero

Next Steps

• Velero can also be used to schedule regular backups of your Kubernetes cluster for disaster recovery. To do this, you can use the velero schedule command.