Populating volumes of a Deployment

This guide will show you how to use KubeStash to populate the volumes of a Deployment. We’ll walk through backing up the volumes of a Deployment and then restoring the backed up data to new PVCs in a Kubernetes-native way with KubeStash.

Before You Begin

At first, you need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using kind.
Install KubeStash in your cluster following the steps here.
You should be familiar with the following KubeStash concepts:

To keep everything isolated, we are going to use a separate namespace called demo throughout this tutorial.

$ kubectl create ns demo
namespace/demo created

Note: YAML files used in this tutorial are stored in docs/guides/volumes/pvc/examples directory of kubestash/docs repository.

Prepare Workload

At first, we are going to deploy a Deployment with two PVCs and generate some sample data in it.

Create PersistentVolumeClaim :

At first, let’s create two sample PVCs. We are going to mount these PVCs in our targeted Deployment.

Below is the YAML of the sample PVCs,

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: source-data
  namespace: demo
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: source-config
  namespace: demo
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi

Let’s create the PVCs we have shown above.

$ kubectl apply -f https://github.com/kubestash/docs/raw/v2024.8.14/docs/guides/volume-populator/deployment/examples/backup-pvcs.yaml
persistentvolumeclaim/source-data created
persistentvolumeclaim/source-config created

Deploy Deployment :

Now, we are going to deploy a Deployment that uses the above PVCs. This Deployment will automatically create data.txt and config.cfg file in /source/data and /source/config directory.

Below is the YAML of the Deployment that we are going to create,

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: kubestash-demo
  name: kubestash-deployment
  namespace: demo
spec:
  replicas: 2
  selector:
    matchLabels:
      app: kubestash-demo
  template:
    metadata:
      labels:
        app: kubestash-demo
      name: busybox
    spec:
      containers:
      - args: ["echo sample_data > /source/data/data.txt; echo sample_config > /source/config/config.cfg  && sleep 3000"]
        command: ["/bin/sh", "-c"]
        image: busybox
        imagePullPolicy: IfNotPresent
        name: busybox
        volumeMounts:
        - mountPath: /source/data
          name: source-data
        - mountPath: /source/config
          name: source-config
      restartPolicy: Always
      volumes:
      - name: source-data
        persistentVolumeClaim:
         claimName: source-data
      - name: source-config
        persistentVolumeClaim:
          claimName: source-config

Let’s create the deployment that we have shown above.

$ kubectl apply -f https://github.com/kubestash/docs/raw/v2024.8.14/docs/guides/volume-populator/deployment/examples/backup-deployment.yaml
deployment.apps/kubestash-deployment created

Now, wait for the pod of the Deployment to go into the Running state.

$ kubectl get pods -n demo
NAME                              READY   STATUS    RESTARTS   AGE
kubestash-deployment-745d49c4cd-vsj8m   1/1     Running   0          62s
kubestash-deployment-745d49c4cd-wwj8w   1/1     Running   0          62s

Verify that the sample data has been created in /source/data and /source/config directory using the following command,

$ kubectl exec -n demo kubestash-deployment-745d49c4cd-vsj8m -- cat /source/data/data.txt
sample_data
$ kubectl exec -n demo kubestash-deployment-745d49c4cd-vsj8m -- cat /source/config/config.cfg
config_data

Prepare Backend

Now, we are going to backup the Deployment kubestash-deployment to a GCS bucket using KubeStash. For this, we have to create a Secret with necessary credentials and a BackupStorage object. If you want to use a different backend, please read the respective backend configuration doc from here.

For GCS backend, if the bucket does not exist, KubeStash needs Storage Object Admin role permissions to create the bucket. For more details, please check the following guide.

Create Secret:

Let’s create a Secret named gcs-secret with access credentials of our desired GCS backend,

$ echo -n '<your-project-id>' > GOOGLE_PROJECT_ID
$ cat /path/to/downloaded/sa_key_file.json > GOOGLE_SERVICE_ACCOUNT_JSON_KEY
$ kubectl create secret generic -n demo gcs-secret \
    --from-file=./GOOGLE_PROJECT_ID \
    --from-file=./GOOGLE_SERVICE_ACCOUNT_JSON_KEY
secret/gcs-secret created

Create BackupStorage:

Now, create a BackupStorage custom resource specifying the desired bucket, and directory inside the bucket where the backed up data will be stored.

Below is the YAML of BackupStorage object that we are going to create,

apiVersion: storage.kubestash.com/v1alpha1
kind: BackupStorage
metadata:
  name: gcs-storage
  namespace: demo
spec:
  storage:
    provider: gcs
    gcs:
      bucket: kubestash-qa
      prefix: demo
      secretName: gcs-secret
  usagePolicy:
    allowedNamespaces:
      from: All
  default: true 
  deletionPolicy: WipeOut

Let’s create the BackupStorage object that we have shown above,

$ kubectl apply -f https://github.com/kubestash/docs/raw/v2024.8.14/docs/guides/volume-populator/deployment/examples/backupstorage.yaml
backupstorage.storage.kubestash.com/gcs-storage created

Now, we are ready to backup our target volume to this backend.

Create RetentionPolicy:

Now, we have to create a RetentionPolicy object to specify how the old Snapshots should be cleaned up.

Below is the YAML of the RetentionPolicy object that we are going to create,

apiVersion: storage.kubestash.com/v1alpha1
kind: RetentionPolicy
metadata:
  name: demo-retention
  namespace: demo
spec:
  default: true
  failedSnapshots:
    last: 2
  maxRetentionPeriod: 2mo
  successfulSnapshots:
    last: 5
  usagePolicy:
    allowedNamespaces:
      from: Same

Notice the spec.usagePolicy that allows referencing the RetentionPolicy from all namespaces.For more details on configuring it for specific namespaces, please refer to the following RetentionPolicy usage policy.

Let’s create the RetentionPolicy object that we have shown above,

$ kubectl apply -f https://github.com/kubestash/docs/raw/v2024.8.14/docs/guides/volume-populator/deployment/examples/retentionpolicy.yaml
retentionpolicy.storage.kubestash.com/demo-retention created

Backup

We have to create a BackupConfiguration custom resource targeting the kubestash-demo Deployment that we have created earlier.

We also have to create another Secret with an encryption key RESTIC_PASSWORD for Restic. This secret will be used by Restic for both encrypting and decrypting the backup data during backup & restore.

Create Secret:

Let’s create a secret named encrypt-secret with the Restic password.

$ echo -n 'changeit' > RESTIC_PASSWORD
$ kubectl create secret generic -n demo encrypt-secret \
    --from-file=./RESTIC_PASSWORD 
secret/encrypt-secret created

Create BackupConfiguration :

Below is the YAML of the BackupConfiguration that we are going to create,

apiVersion: core.kubestash.com/v1alpha1
kind: BackupConfiguration
metadata:
  name: sample-backup-dep
  namespace: demo
spec:
  target:
    apiGroup: apps
    kind: Deployment
    name:  kubestash-deployment
    namespace: demo
  backends:
    - name: gcs-backend
      storageRef:
        namespace: demo
        name: gcs-storage
      retentionPolicy:
        name: demo-retention
        namespace: demo
  sessions:
    - name: frequent-backup
      sessionHistoryLimit: 3
      scheduler:
        schedule: "*/5 * * * *"
        jobTemplate:
          backoffLimit: 1
      repositories:
        - name: gcs-repository
          backend: gcs-backend
          directory: /dep
          encryptionSecret:
            name: encrypt-secret # some addon may not support encryption
            namespace: demo
          deletionPolicy: WipeOut
      addon:
        name: workload-addon
        tasks:
          - name: logical-backup
            params:
              paths: /source/data,/source/config
              exclude: /source/data/lost+found,/source/config/lost+found

Let’s create the BackupConfiguration object we have shown above.

$ kubectl apply -f https://github.com/kubestash/docs/raw/v2024.8.14/docs/guides/volume-populator/deployment/examples/backupconfiguration.yaml
backupconfiguration.core.kubestash.com/sample-backup-dep created

Verify Backup Setup Successful:

If everything goes well, the phase of the BackupConfiguration should be in Ready state. The Ready phase indicates that the backup setup is successful.

Let’s check the Phase of the BackupConfiguration,

$ kubectl get backupconfiguration -n demo
NAME                PHASE   PAUSED   AGE
sample-backup-dep   Ready            2m50s

Verify Repository:

Verify that the Repository specified in the BackupConfiguration has been created using the following command,

$ kubectl get repositories -n demo
NAME             INTEGRITY   SNAPSHOT-COUNT   SIZE   PHASE   LAST-SUCCESSFUL-BACKUP   AGE
gcs-repository                                       Ready                            28s

KubeStash keeps the backup for Repository YAMLs. If we navigate to the GCS bucket, we will see the Repository YAML stored in the kubestash-qa/demo/dep directory.

Verify CronJob:

Verify that KubeStash has created a CronJob with the schedule specified in spec.sessions[*].scheduler.schedule field of BackupConfiguration object.

Check that the CronJob has been created using the following command,

$ kubectl get cronjob -n demo
NAME                                                 SCHEDULE      SUSPEND   ACTIVE   LAST SCHEDULE   AGE
trigger-sample-backup-dep-frequent-backup               */5 * * * *   False     0        <none>          20s

Wait for BackupSession:

Now, wait for the next backup schedule. You can watch for BackupSession CR using the following command,

$ watch -n 1 kubectl get backupsession -n demo -l=kubestash.com/invoker-name=sample-backup-dep

Every 1.0s: kubectl get backupsession -n demo -l=kubestash.com/invoker-name=sample-backup-dep                                       anisur: Wed Jan 17 15:20:09 2024

NAME                                                    INVOKER-TYPE          INVOKER-NAME                 PHASE     DURATION   AGE
sample-backup-dep-frequent-backup-1705483201            BackupConfiguration   sample-backup-dep            Running              9s

Here, the phase Succeeded means that the backup process has been completed successfully.

Verify Backup:

When backup session is complete, KubeStash will update the respective Repository object to reflect the backup. Check that the repository gcs-repository has been updated by the following command,

$ kubectl get repository -n demo gcs-demo-repo
NAME              INTEGRITY   SNAPSHOT-COUNT   SIZE    PHASE   LAST-SUCCESSFUL-BACKUP   AGE
gcs-repository    true        1                806 B   Ready   8m27s                    9m18s

At this moment we have one Snapshot. Run the following command to check the respective Snapshot.

Verify created Snapshot object by the following command,

$ kubectl get snapshots -n demo -l=kubestash.com/repo-name=gcs-repository
NAME                                                          REPOSITORY      SESSION        SNAPSHOT-TIME          DELETION-POLICY   PHASE       AGE
gcs-repository-sample-backup-dep-frequent-backup-1706015400   gcs-demo-repo   demo-session   2024-01-23T13:10:54Z   Delete            Succeeded   16h

When a backup is triggered according to schedule, KubeStash will create a Snapshot with the following labels kubestash.com/app-ref-kind: PersistentVolumeClaim, kubestash.com/app-ref-name: <pvc-name>, kubestash.com/app-ref-namespace: <pvc-namespace> and kubestash.com/repo-name: <repository-name>. We can use these labels to watch only the Snapshot of our desired Workload or Repository.

Now, lets retrieve the YAML for the Snapshot, and inspect the spec.status section to see the backup up components of the Deployment.

$ kubectl get snapshots -n demo gcs-repository-sample-backup-dep-frequent-backup-1706015400 -oyaml

apiVersion: storage.kubestash.com/v1alpha1
kind: Snapshot
metadata:
  labels:
    kubestash.com/app-ref-kind: Deployment
    kubestash.com/app-ref-name: kubestash-deployment
    kubestash.com/app-ref-namespace: demo
    kubestash.com/repo-name: gcs-repository
  name: gcs-repository-sample-backup-dep-frequent-backup-1706015400
  namespace: demo
spec:
  ...
status:
  components:
    dump:
      driver: Restic
      duration: 7.534461497s
      integrity: true
      path: repository/v1/frequent-backup/dump
      phase: Succeeded
      resticStats:
      - hostPath: /source/data
        id: f28441a36b2167d64597d66d1046573181cad81aa8ff5b0998b64b31ce16f077
        size: 11 B
        uploaded: 1.049 KiB
      - hostPath: /source/config
        id: f28441a36b2167d64597d66d1046573181cad81aa8ff5b0998b64b31ce16f077
        size: 11 B
        uploaded: 1.049 KiB
      size: 806 B
  ...

For Deployment, KubeStash takes backup from only one pod of the Deployment. So, only one component has been taken backup. The component name is dump.

Populate Volumes

This section will show you how to populate the volumes of a Deployment with data from the Snapshot of the previous backup using KubeStash.

Create PersistentVolumeClaim :

Now, we need to create two new Persistent Volume Claims (PVCs) with the spec.dataSourceRef set to reference our Snapshot object.

Below is the YAML of the PVCs,

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: restored-source-data
  namespace: demo
  annotations:
        populator.kubestash.com/app-name: kubestash-restored-deployment
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
  dataSourceRef:
    apiGroup: storage.kubestash.com
    kind: Snapshot
    name: gcs-repository-sample-backup-dep-frequent-backup-1706015400
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: restored-source-data
  namespace: demo
  annotations:
        populator.kubestash.com/app-name: kubestash-restored-deployment
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
  dataSourceRef:
    apiGroup: storage.kubestash.com
    kind: Snapshot
    name: gcs-repository-sample-backup-dep-frequent-backup-1706015400

Here,

spec.dataSourceRef specifies that which snapshot we want to use for restoring and populating the volume. We have referenced the Snapshot object that was backed up in the previous section
metadata.annotations.populator.kubestash.com/app-name field is mandatory for any volume population of a deployment through KubeStash.
- This field denotes the deployment that will be attached those volumes via mount paths. The volume population will only be successful if the mount path of this volume matches the mount paths of the backup deployment.
- For example, you backed up a deployment with volumes named source-data and source-config, each with corresponding mount paths /source/data and /source/config. Now you wish to populate volumes named restore-source-data and restore-source-config attached to a deployment named restored-kubestash-deployment, then this deployment must have mount paths set to /source/data and /source/config, respectively.

Let’s create the PVCs YAMl that we have shown above.

$ kubectl apply -f https://github.com/kubestash/docs/raw/v2024.8.14/docs/guides/volume-populator/deployment/examples/populated-pvcs.yaml
persistentvolumeclaim/restored-source-data created
persistentvolumeclaim/restored-source-config created

Deploy Deployment :

Now, we are going to deploy a Deployment that uses the above PVCs. This Deployment has mount paths /source/data and /source/config corresponding to volumes named restored-source-data and restored-source-config respectively.

Below is the YAML of the Deployment that we are going to create,

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: kubestash-demo
  name: restored-kubestash-deployment
  namespace: demo
spec:
  replicas: 1
  selector:
    matchLabels:
      app: kubestash-demo
  template:
    metadata:
      labels:
        app: kubestash-demo
      name: busybox
    spec:
      containers:
      - command: ["/bin/sh", "-c"]
        image: busybox
        imagePullPolicy: IfNotPresent
        name: busybox
        volumeMounts:
        - mountPath: /source/data
          name: source-data
        - mountPath: /source/config
          name: source-config
      restartPolicy: Always
      volumes:
      - name: restored-source-data
        persistentVolumeClaim:
         claimName: source-data
      - name: restored-source-config
        persistentVolumeClaim:
          claimName: source-config

Let’s create the deployment we have shown above.

$ kubectl apply -f https://github.com/kubestash/docs/raw/v2024.8.14/docs/guides/volume-populator/deployment/examples/restore-deployment.yaml
deployment.apps/restored-kubestash-deployment created

Wait for Populate Volume:

When you create two PVCs with spec.dataSourceRef that refers our Snapshot object, KubeStash automatically creates a populator Job. Now, just wait for the volume population process to finish.

You can watch the PVCs status using the following command,

$ watch kubectl get pvc -n demo 

Every 2.0s: kubectl get pvc -n demo                                                                   anisur: Tue Feb 13 18:37:26 2024

NAME                     STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
restored-source-config   Bound    pvc-27a19e86-0ed5-4b18-9263-c8a66459aeb0   1Gi        RWO            standard-rwo   2m50s
restored-source-data     Bound    pvc-d210787e-5137-40b7-89e7-73d982716b40   1Gi        RWO            standard-rwo   2m51s

The output of the command shows the PVCs status as Bound, indicating successful completion of the volume population.

Verify Restored Data :

We are going to exec a pod of restored-dep deployment to verify whether the restored data.

Now, wait for the deployment pod to go into the Running state.

$ kubectl get pods -n demo 
NAME                                             READY   STATUS    RESTARTS   AGE
restored-kubestash-deployment-84b974dfb5-4jzjd   1/1     Running   0          2m48s

Verify that the backed up data has been restored into /source/data and /source/config directory of above pod using the following command,

$ kubectl exec -it -n demo restored-kubestash-deployment-84b974dfb5-4jzjd -- cat /source/data/data.txt
sample_data

$ kubectl exec -it -n demo restored-kubestash-deployment-84b974dfb5-4jzjd -- cat /source/config/config.cfg
sample_config

Cleaning Up

To clean up the Kubernetes resources created by this tutorial, run:

kubectl delete backupconfiguration -n demo sample-backup-dep
kubectl delete backupstorage -n demo gcs-storage
kubectl delete retentionPolicy -n demo demo-retention
kubectl delete secret -n demo gcs-secret
kubectl delete secret -n demo encrypt-secret
kubectl delete deploy -n demo kubestash-deployment restored-kubestash-deployment
kubectl delete pvc -n demo --all

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