Backup and Restore Volumes of a Deployment

This guide will show you how to use Stash to backup and restore volumes of a Deployment.

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 Stash in your cluster following the steps here.

  • You should be familiar with the following Stash 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/examples/guides/latest/workloads directory of stashed/docs repository.

Backup Volumes of a Deployment

This section will show you how to use Stash to backup volumes of a Deployment. Here, we are going to deploy a Deployment with a PVC and generate some sample data in it. Then, we are going to backup this sample data using Stash.

Prepare Workload

At first, we are going to create a PVC then we are going to create a Deployment that will use this PVC.

Create PVC:

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

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

Let’s create the PVC we have shown above,

$ kubectl apply -f https://github.com/stashed/docs/raw/v2020.08.27/docs/examples/guides/latest/workloads/deployment/pvc.yaml
persistentvolumeclaim/stash-sample-data created

Deploy Deployment:

Now, we are going to deploy a Deployment that uses the above PVC. This Deployment will automatically generate sample data (data.txt file) in /source/data directory where we have mounted the PVC.

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

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: stash-demo
  name: stash-demo
  namespace: demo
spec:
  replicas: 3
  selector:
    matchLabels:
      app: stash-demo
  template:
    metadata:
      labels:
        app: stash-demo
      name: busybox
    spec:
      containers:
      - args: ["echo sample_data > /source/data/data.txt && sleep 3000"]
        command: ["/bin/sh", "-c"]
        image: busybox
        imagePullPolicy: IfNotPresent
        name: busybox
        volumeMounts:
        - mountPath: /source/data
          name: source-data
      restartPolicy: Always
      volumes:
      - name: source-data
        persistentVolumeClaim:
          claimName: stash-sample-data

Let’s create the Deployment we have shown above.

$ kubectl apply -f https://github.com/stashed/docs/raw/v2020.08.27/docs/examples/guides/latest/workloads/deployment/deployment.yaml
deployment.apps/stash-demo created

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

$ kubectl get pod -n demo
NAME                         READY   STATUS    RESTARTS   AGE
stash-demo-8cfcbcc89-2z6mq   1/1     Running   0          30s
stash-demo-8cfcbcc89-j9wbc   1/1     Running   0          30s
stash-demo-8cfcbcc89-q8xfd   1/1     Running   0          30s

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

$ kubectl exec -n demo stash-demo-8cfcbcc89-2z6mq -- cat /source/data/data.txt
sample_data

Prepare Backend

We are going to store our backed up data into a GCS bucket. We have to create a Secret with necessary credentials and a Repository crd to use this backend. 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, Stash 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 called gcs-secret with access credentials to our desired GCS bucket,

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

Create Repository:

Now, create a Repository using this secret. Below is the YAML of Repository crd we are going to create,

apiVersion: stash.appscode.com/v1alpha1
kind: Repository
metadata:
  name: gcs-repo
  namespace: demo
spec:
  backend:
    gcs:
      bucket: appscode-qa
      prefix: /source/data/sample-deployment
    storageSecretName: gcs-secret

Let’s create the Repository we have shown above,

$ kubectl apply -f https://github.com/stashed/docs/raw/v2020.08.27/docs/examples/guides/latest/workloads/deployment/repository.yaml
repository.stash.appscode.com/gcs-repo created

Now, we are ready to backup our sample data into this backend.

Backup

We have to create a BackupConfiguration crd targeting the stash-demo Deployment that we have deployed earlier. Stash will inject a sidecar container into the target. It will also create a CronJob to take periodic backup of /source/data directory of the target.

Create BackupConfiguration:

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

apiVersion: stash.appscode.com/v1beta1
kind: BackupConfiguration
metadata:
  name: deployment-backup
  namespace: demo
spec:
  repository:
    name: gcs-repo
  schedule: "*/5 * * * *"
  target:
    ref:
      apiVersion: apps/v1
      kind: Deployment
      name: stash-demo
    volumeMounts:
    - name: source-data
      mountPath: /source/data
    paths:
    - /source/data
  retentionPolicy:
    name: 'keep-last-5'
    keepLast: 5
    prune: true

Here,

  • spec.repository refers to the Repository object gcs-repo that holds backend information.
  • spec.schedule is a cron expression that indicates BackupSession will be created at 5 minute interval.
  • spec.target.ref refers to the stash-demo Deployment.
  • spec.target.volumeMounts specifies a list of volumes and their mountPath that contain the target paths.
  • spec.target.paths specifies list of file paths to backup.

Let’s create the BackupConfiguration crd we have shown above,

$ kubectl apply -f https://github.com/stashed/docs/raw/v2020.08.27/docs/examples/guides/latest/workloads/deployment/backupconfiguration.yaml
backupconfiguration.stash.appscode.com/deployment-backup created

Verify Sidecar:

If everything goes well, Stash will inject a sidecar container into the stash-demo Deployment to take backup of /source/data directory. Let’s check that the sidecar has been injected successfully,

$ kubectl get pod -n demo
NAME                          READY   STATUS        RESTARTS   AGE
stash-demo-856896bd95-4gfbh   2/2     Running       0          12s
stash-demo-856896bd95-njr8x   2/2     Running       0          17s
stash-demo-856896bd95-ttbq4   2/2     Running       0          15s

Look at the pod. It now has 2 containers. If you view the resource definition of this pod, you will see that there is a container named stash which is running run-backup command.

$ kubectl get pod -n demo stash-demo-856896bd95-4gfbh -o yaml
apiVersion: v1
kind: Pod
metadata:
  name: stash-demo-856896bd95-4gfbh
  namespace: demo
 ...
spec:
  containers:
  - args:
    - echo sample_data > /source/data/data.txt && sleep 3000
    command:
    - /bin/sh
    - -c
    image: busybox
    imagePullPolicy: IfNotPresent
    name: busybox
    resources: {}
    terminationMessagePath: /dev/termination-log
    terminationMessagePolicy: File
    volumeMounts:
    - mountPath: /source/data
      name: source-data
    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: default-token-4tzgg
      readOnly: true
  - args:
    - run-backup
    - --backup-configuration=deployment-backup
    - --secret-dir=/etc/stash/repository/secret
    - --enable-cache=true
    - --max-connections=0
    - --metrics-enabled=true
    - --pushgateway-url=http://stash-operator.kube-system.svc:56789
    - --enable-status-subresource=true
    - --use-kubeapiserver-fqdn-for-aks=true
    - --enable-analytics=true
    - --logtostderr=true
    - --alsologtostderr=false
    - --v=3
    - --stderrthreshold=0
    env:
    - name: NODE_NAME
      valueFrom:
        fieldRef:
          apiVersion: v1
          fieldPath: spec.nodeName
    - name: POD_NAME
      valueFrom:
        fieldRef:
          apiVersion: v1
          fieldPath: metadata.name
    volumeMounts:
    - mountPath: /etc/stash
      name: stash-podinfo
    - mountPath: /etc/stash/repository/secret
      name: stash-secret-volume
    - mountPath: /tmp
      name: tmp-dir
    - mountPath: /source/data
      name: source-data
    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: default-token-4tzgg
      readOnly: true
  volumes:
  - name: source-data
    persistentVolumeClaim:
      claimName: stash-sample-data
  - emptyDir: {}
    name: tmp-dir
  - downwardAPI:
      defaultMode: 420
      items:
      - fieldRef:
          apiVersion: v1
          fieldPath: metadata.labels
        path: labels
    name: stash-podinfo
  - name: stash-secret-volume
    secret:
      defaultMode: 420
      secretName: gcs-secret
  - name: default-token-4tzgg
    secret:
      defaultMode: 420
      secretName: default-token-4tzgg
  ...
...

Verify CronJob:

It will also create a CronJob with the schedule specified in spec.schedule field of BackupConfiguration crd.

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

$ kubectl get cronjob -n demo
NAME                SCHEDULE      SUSPEND   ACTIVE   LAST SCHEDULE   AGE
deployment-backup   */1 * * * *   False     0        35s             64s

Wait for BackupSession:

The deployment-backup CronJob will trigger a backup on each scheduled slot by creating a BackupSession crd. The sidecar container watches for the BackupSession crd. When it finds one, it will take backup immediately.

Wait for the next schedule for backup. Run the following command to watch BackupSession crd,

$ watch -n 2 kubectl get backupsession -n demo
Every 1.0s: kubectl get backupsession -n demo     suaas-appscode: Mon Jun 24 10:23:08 2019

NAME                           INVOKER-TYPE          INVOKER-NAME        PHASE       AGE
deployment-backup-1561350125   BackupConfiguration   deployment-backup   Succeeded   63s

We can see from the above output that the backup session has succeeded. Now, we are going to verify whether the backed up data has been stored in the backend.

Verify Backup:

Once a backup is complete, Stash will update the respective Repository crd to reflect the backup. Check that the repository gcs-repo has been updated by the following command,

$ kubectl get repository -n demo gcs-repo
NAME       INTEGRITY   SIZE   SNAPSHOT-COUNT   LAST-SUCCESSFUL-BACKUP   AGE
gcs-repo   true        0 B    5                58s                      18m

Now, if we navigate to the GCS bucket, we are going to see backed up data has been stored in source/data/sample-deployment directory as specified by spec.backend.gcs.prefix field of Repository crd.

  Backup data in GCS Bucket
Fig: Backup data in GCS Bucket

Note: Stash keeps all the backed up data encrypted. So, data in the backend will not make any sense until they are decrypted.

Restore the Backed up Data

This section will show you how to restore the backed up data from the backend we have taken in the earlier section.

Stop Taking Backup of the Old Deployment:

At first, let’s stop taking any further backup of the old Deployment so that no backup is taken during the restore process. We are going to pause the BackupConfiguration that we created to backup the stash-demo Deployment. Then, Stash will stop taking any further backup for this Deployment. You can learn more how to pause a scheduled backup here

Let’s pause the deployment-backup BackupConfiguration,

$ kubectl patch backupconfiguration -n demo deployment-backup --type="merge" --patch='{"spec": {"paused": true}}'
backupconfiguration.stash.appscode.com/deployment-backup patched

Now, wait for a moment. Stash will pause the BackupConfiguration. Verify that the BackupConfiguration has been paused,

$ kubectl get backupconfiguration -n demo
NAME                TASK   SCHEDULE      PAUSED   AGE
deployment-backup          */1 * * * *   true     26m

Notice the PAUSED column. Value true for this field means that the BackupConfiguration has been paused.

Deploy Deployment:

We are going to create a new Deployment named stash-recovered and restore the backed up data inside it.

Below are the YAMLs of the Deployment and PVC that we are going to create,

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: demo-pvc
  namespace: demo
spec:
  accessModes:
  - ReadWriteOnce
  storageClassName: standard
  resources:
    requests:
      storage: 1Gi
---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: stash-recovered
  name: stash-recovered
  namespace: demo
spec:
  replicas: 3
  selector:
    matchLabels:
      app: stash-recovered
  template:
    metadata:
      labels:
        app: stash-recovered
      name: busybox
    spec:
      containers:
      - args:
        - sleep
        - "3600"
        image: busybox
        imagePullPolicy: IfNotPresent
        name: busybox
        volumeMounts:
        - mountPath: /source/data
          name: source-data
      restartPolicy: Always
      volumes:
      - name: source-data
        persistentVolumeClaim:
          claimName: demo-pvc

Let’s create the Deployment and PVC we have shown above.

$ kubectl apply -f https://github.com/stashed/docs/raw/v2020.08.27/docs/examples/guides/latest/workloads/deployment/recovered_deployment.yaml
persistentvolumeclaim/demo-pvc created
deployment.apps/stash-recovered created

Create RestoreSession:

Now, we need to create a RestoreSession crd targeting the stash-recovered Deployment to restore the backed up data inside it.

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

apiVersion: stash.appscode.com/v1beta1
kind: RestoreSession
metadata:
  name: deployment-restore
  namespace: demo
spec:
  repository:
    name: gcs-repo
  target: # target indicates where the recovered data will be stored
    ref:
      apiVersion: apps/v1
      kind: Deployment
      name: stash-recovered
    volumeMounts:
    - name:  source-data
      mountPath:  /source/data
    rules:
    - paths:
      - /source/data/

Here,

  • spec.repository.name specifies the Repository crd that holds the backend information where our backed up data has been stored.
  • spec.target.ref refers to the target workload where the recovered data will be stored.
  • spec.target.volumeMounts specifies a list of volumes and their mountPath where the data will be restored.
    • mountPath must be same mountPath as the original volume because Stash stores absolute path of the backed up files. If you use different mountPath for the restored volume the backed up files will not be restored into your desired volume.

Let’s create the RestoreSession crd we have shown above,

$ kubectl apply -f https://github.com/stashed/docs/raw/v2020.08.27/docs/examples/guides/latest/workloads/deployment/restoresession.yaml
restoresession.stash.appscode.com/deployment-restore created

Once, you have created the RestoreSession crd, Stash will inject init-container into stash-recovered Deployment. Deployment will restart and the init-container will restore the desired data on start-up.

Verify Init-Container:

Wait until the init-container has been injected into the stash-recovered Deployment. Let’s describe the Deployment to verify that init-container has been injected successfully.

$ kubectl describe deployment -n demo stash-recovered
Name:                   stash-recovered
Namespace:              demo
Labels:                 app=stash-recovered
Selector:               app=stash-recovered
Replicas:               3 desired | 3 updated | 3 total | 3 available |
...
Pod Template:
  Labels:       app=stash-recovered
  Annotations:  stash.appscode.com/last-applied-restoresession-hash: 14443247646000846167
  Init Containers:
   stash-init:
    Image:      suaas21/stash:vs_linux_amd64
    Port:       <none>
    Host Port:  <none>
    Args:
      restore
      --restore-session=deployment-restore
      --secret-dir=/etc/stash/repository/secret
      --enable-cache=true
      --max-connections=0
      --metrics-enabled=true
      --pushgateway-url=http://stash-operator.kube-system.svc:56789
      --enable-status-subresource=true
      --use-kubeapiserver-fqdn-for-aks=true
      --enable-analytics=true
      --logtostderr=true
      --alsologtostderr=false
      --v=3
      --stderrthreshold=0
    Environment:
      NODE_NAME:   (v1:spec.nodeName)
      POD_NAME:    (v1:metadata.name)
    Mounts:
      /etc/stash/repository/secret from stash-secret-volume (rw)
      /source/data from source-data (rw)
      /tmp from tmp-dir (rw)
  Containers:
   busybox:
    Image:      busybox
    Port:       <none>
    Host Port:  <none>
    Args:
      sleep
      3600
    Environment:  <none>
    Mounts:
      /source/data from source-data (rw)
  Volumes:
   source-data:
    Type:       PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
    ClaimName:  demo-pvc
    ReadOnly:   false
   tmp-dir:
    Type:       EmptyDir (a temporary directory that shares a pod's lifetime)
    Medium:
    SizeLimit:  <unset>
   stash-podinfo:
    Type:  DownwardAPI (a volume populated by information about the pod)
    Items:
      metadata.labels -> labels
   stash-secret-volume:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  gcs-secret
    Optional:    false
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  stash-recovered-7478988f57 (3/3 replicas created)
NewReplicaSet:   <none>
...

Notice the Init-Containers section. We can see that the init-container stash-init has been injected which is running restore command.

Wait for RestoreSession to Succeeded:

Run the following command to watch RestoreSession phase,

$ watch -n 2 kubectl get restoresession -n demo
Every 5.0s: kubectl get restoresession -n demo           suaas-appscode: Mon Jun 24 10:33:57 2019

NAME                 REPOSITORY-NAME   PHASE       AGE
deployment-restore   gcs-repo          Succeeded   2m56s

So, we can see from the output of the above command that the restore process succeeded.

Note: If you want to restore the backed up data inside the same Deployment whose volumes were backed up, you have to remove the corrupted data from the Deployment. Then, you have to create a RestoreSession targeting the Deployment.

Verify Restored Data:

In this section, we are going to verify that the desired data has been restored successfully.

At first, check if the stash-recovered pods of the Deployment has gone into Running state by the following command,

$ kubectl get pod -n demo
NAME                               READY   STATUS    RESTARTS   AGE
stash-recovered-867688ddd5-67xr8   1/1     Running   0          21m
stash-recovered-867688ddd5-rfsw4   1/1     Running   0          21m
stash-recovered-867688ddd5-zswhs   1/1     Running   0          22m

Verify that the sample data has been restored in /source/data directory of the stash-recovered pods of the Deployment using the following command,

$ kubectl exec -n demo stash-recovered-867688ddd5-67xr8 -- cat /source/data/data.txt
sample_data

Cleaning Up

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

kubectl delete -n demo deployment stash-demo
kubectl delete -n demo deployment stash-recovered
kubectl delete -n demo backupconfiguration deployment-backup
kubectl delete -n demo restoresession deployment-restore
kubectl delete -n demo repository gcs-repo
kubectl delete -n demo pvc --all