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Offline Backup

This tutorial will show you how to backup a Kubernetes deployment using Stash in offline mode. By default, stash takes backup in online mode where sidecar container is added to take periodic backups and check backups. But sometimes you need to ensure that source data is not being modified while taking the backup, that means running backup while keeping workload pod stopped. In such case, you can run the backup in offline mode. To do this you need to specify spec.type: offline in Restic crd.

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:
You will need an NFS server to store backed up data. If you already do not have an NFS server running, deploy one following the tutorial from here. For this tutorial, we have deployed NFS server in storage namespace and it is accessible through nfs-service.storage.svc.cluster.local dns.

To keep things 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/backup directory of stashed/docs repository.

Overview

The following diagram shows how Stash takes offline backup of a Kubernetes volume. Open the image in a new tab to see the enlarged version.

Stash Offline Backup Flow

The offline backup process consists of the following steps:

At first, a user creates a Secret. This secret holds the credentials to access the backend where backed up data will be stored. It also holds a password (RESTIC_PASSWORD) that will be used to encrypt the backed up data.
Then, the user creates a Restic crd which specifies the targeted workload for backup. It also specifies the backend information where the backed up data will be stored.
Stash operator watches for Restic crd. Once it sees a Restic crd, it identifies the targeted workload that matches the selector of this Restic.
Then, Stash operator injects an init-container named stash and mounts the target volume in it.
Stash operator creates a CronJob with name stash-scaledown-cron-{restic-name}.
The CronJob restarts workload on the scheduled interval.
Finally, stash init-container takes backup of the volume to the specified backend when pod restarts. It also creates a Repository crd during the first backup which represents the backend in a Kubernetes native way.

The CronJob restarts workloads according to the following rules:

If the workload is a StatefulSet or a DaemonSet, it will delete all pods of the workload. The workload will automatically re-creates the pods and each pod will take backup with their init-container.
If the workload is a Deployment, ReplicaSet or ReplicationController, it will scale down the workload to 0 replica. When all pods are terminated, it will scale up the workload to 1 replica. This single replica will take backup with init-container. When backup is complete, the init-container will scale up the workload to original replica. The rest of the replicas will not take backup even through they have init-container.

Backup

In order to take backup, we need some sample data. Stash has some sample data in appscode/stash-data repository. As gitRepo volume has been deprecated, we are not going to use this repository as volume directly. Instead, we are going to create a configMap from the stash-data repository and use that ConfigMap as data source.

Let’s create a ConfigMap from these sample data,

$ kubectl create configmap -n demo stash-sample-data \
	--from-literal=LICENSE="$(curl -fsSL https://github.com/stashed/stash-data/raw/master/LICENSE)" \
	--from-literal=README.md="$(curl -fsSL https://github.com/stashed/stash-data/raw/master/README.md)"
configmap/stash-sample-data created

Here, we are going to backup the /source/data folder of a busybox pod into an NFS volume. NFS volume is a type of local backend for Stash.

Deploy Workload:

Now, deploy the following Deployment. Here, we have mounted the ConfigMap stash-sample-data as data source volume.

Below, the YAML for the Deployment we are going to create.

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: stash-demo
  name: stash-demo
  namespace: demo
spec:
  replicas: 1
  selector:
    matchLabels:
      app: stash-demo
  template:
    metadata:
      labels:
        app: stash-demo
      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
        configMap:
          name: stash-sample-data

Let’s create the deployment we have shown above,

$ kubectl apply -f https://github.com/stashed/docs/raw/v2021.03.08/docs/examples/backup/deployment.yaml
deployment.apps/stash-demo created

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

$ kubectl get pod -n demo -l app=stash-demo
NAME                          READY   STATUS    RESTARTS   AGE
stash-demo-7ccd56bf5d-p9p2p   1/1     Running   0          2m29s

You can check that the /source/data/ directory of this pod is populated with data from the stash-sample-data ConfigMap using this command,

$ kubectl exec -n demo stash-demo-7ccd56bf5d-p9p2p -- ls -R /source/data
/source/data:
LICENSE
README.md

Now, we are ready to backup /source/data directory into an NFS backend.

Create Secret:

At first, we need to create a storage secret. To configure this backend, the following secret keys are needed:

Key	Description
`RESTIC_PASSWORD`	`Required`. Password used to encrypt snapshots by `restic`

Create the secret as below,

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

Verify that the secret has been created successfully.

$ kubectl get secret -n demo local-secret -o yaml

apiVersion: v1
data:
  RESTIC_PASSWORD: Y2hhbmdlaXQ=
kind: Secret
metadata:
  creationTimestamp: 2018-12-07T11:44:09Z
  name: local-secret
  namespace: demo
  resourceVersion: "36409"
  selfLink: /api/v1/namespaces/demo/secrets/local-secret
  uid: 68ab5960-fa15-11e8-8905-0800277ca39d
type: Opaque

Create Restic:

Now, we are going to create Restic crd to take backup /source/data directory of stash-demo deployment in offline mode.

Below, the YAML for Restic crd we are going to create for offline backup,

apiVersion: stash.appscode.com/v1alpha1
kind: Restic
metadata:
  name: offline-restic
  namespace: demo
spec:
  selector:
    matchLabels:
      app: stash-demo
  type: offline
  fileGroups:
  - path: /source/data
    retentionPolicyName: 'keep-last-5'
  backend:
    local:
      mountPath: /safe/data
      nfs:
        server: "nfs-service.storage.svc.cluster.local"
        path: "/"
    storageSecretName: local-secret
  schedule: '@every 5m'
  volumeMounts:
  - mountPath: /source/data
    name: source-data
  retentionPolicies:
  - name: 'keep-last-5'
    keepLast: 5
    prune: true

Here, we have set spec.type: offline. This tell Stash to take backup in offline mode.

Let’s create the Restic we have shown above,

$ kubectl apply -f https://github.com/stashed/docs/raw/v2021.03.08/docs/examples/backup/restic_offline.yaml
restic.stash.appscode.com/offline-restic created

If everything goes well, Stash will inject an init-container into the stash-demo deployment to take backup while pod starts.

Let’s check that init-container has been injected successfully,

$ kubectl get deployment -n demo stash-demo -o yaml

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  annotations:
    deployment.kubernetes.io/revision: "2"
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{},"labels":{"app":"stash-demo"},"name":"stash-demo","namespace":"demo"},"spec":{"replicas":1,"selector":{"matchLabels":{"app":"stash-demo"}},"template":{"metadata":{"labels":{"app":"stash-demo"},"name":"busybox"},"spec":{"containers":[{"args":["sleep","3600"],"image":"busybox","imagePullPolicy":"IfNotPresent","name":"busybox","volumeMounts":[{"mountPath":"/source/data","name":"source-data"}]}],"restartPolicy":"Always","volumes":[{"configMap":{"name":"stash-sample-data"},"name":"source-data"}]}}}}      
    restic.appscode.com/last-applied-configuration: |
      {"kind":"Restic","apiVersion":"stash.appscode.com/v1alpha1","metadata":{"name":"offline-restic","namespace":"demo","selfLink":"/apis/stash.appscode.com/v1alpha1/namespaces/demo/restics/offline-restic","uid":"f5b3abe7-fa15-11e8-8905-0800277ca39d","resourceVersion":"36693","generation":1,"creationTimestamp":"2018-12-07T11:48:05Z","annotations":{"kubectl.kubernetes.io/last-applied-configuration":"{\"apiVersion\":\"stash.appscode.com/v1alpha1\",\"kind\":\"Restic\",\"metadata\":{\"annotations\":{},\"name\":\"offline-restic\",\"namespace\":\"demo\"},\"spec\":{\"backend\":{\"local\":{\"mountPath\":\"/safe/data\",\"nfs\":{\"path\":\"/\",\"server\":\"nfs-service.storage.svc.cluster.local\"}},\"storageSecretName\":\"local-secret\"},\"fileGroups\":[{\"path\":\"/source/data\",\"retentionPolicyName\":\"keep-last-5\"}],\"retentionPolicies\":[{\"keepLast\":5,\"name\":\"keep-last-5\",\"prune\":true}],\"schedule\":\"@every 5m\",\"selector\":{\"matchLabels\":{\"app\":\"stash-demo\"}},\"type\":\"offline\",\"volumeMounts\":[{\"mountPath\":\"/source/data\",\"name\":\"source-data\"}]}}\n"}},"spec":{"selector":{"matchLabels":{"app":"stash-demo"}},"fileGroups":[{"path":"/source/data","retentionPolicyName":"keep-last-5"}],"backend":{"storageSecretName":"local-secret","local":{"nfs":{"server":"nfs-service.storage.svc.cluster.local","path":"/"},"mountPath":"/safe/data"}},"schedule":"@every 5m","volumeMounts":[{"name":"source-data","mountPath":"/source/data"}],"resources":{},"retentionPolicies":[{"name":"keep-last-5","keepLast":5,"prune":true}],"type":"offline"}}      
    restic.appscode.com/tag: e3
  creationTimestamp: 2018-12-07T11:40:30Z
  generation: 2
  labels:
    app: stash-demo
  name: stash-demo
  namespace: demo
  resourceVersion: "36735"
  selfLink: /apis/extensions/v1beta1/namespaces/demo/deployments/stash-demo
  uid: e6996fbd-fa14-11e8-8905-0800277ca39d
spec:
  progressDeadlineSeconds: 600
  replicas: 1
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: stash-demo
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
    type: RollingUpdate
  template:
    metadata:
      annotations:
        restic.appscode.com/resource-hash: "16527601205197612609"
      creationTimestamp: null
      labels:
        app: stash-demo
      name: busybox
    spec:
      containers:
      - args:
        - sleep
        - "3600"
        image: busybox
        imagePullPolicy: IfNotPresent
        name: busybox
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
        volumeMounts:
        - mountPath: /source/data
          name: source-data
      dnsPolicy: ClusterFirst
      initContainers:
      - args:
        - backup
        - --restic-name=offline-restic
        - --workload-kind=Deployment
        - --workload-name=stash-demo
        - --docker-registry=appscodeci
        - --image-tag=e3
        - --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
        - --enable-rbac=true
        env:
        - name: NODE_NAME
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: spec.nodeName
        - name: POD_NAME
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: metadata.name
        - name: APPSCODE_ANALYTICS_CLIENT_ID
          value: 90b12fedfef2068a5f608219d5e7904a
        image: appscodeci/stash:e3
        imagePullPolicy: IfNotPresent
        name: stash
        resources: {}
        securityContext:
          procMount: Default
          runAsUser: 0
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
        volumeMounts:
        - mountPath: /tmp
          name: stash-scratchdir
        - mountPath: /etc/stash
          name: stash-podinfo
        - mountPath: /source/data
          name: source-data
          readOnly: true
        - mountPath: /safe/data
          name: stash-local
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30
      volumes:
      - configMap:
          defaultMode: 420
          name: stash-sample-data
        name: source-data
      - emptyDir: {}
        name: stash-scratchdir
      - downwardAPI:
          defaultMode: 420
          items:
          - fieldRef:
              apiVersion: v1
              fieldPath: metadata.labels
            path: labels
        name: stash-podinfo
      - name: stash-local
        nfs:
          path: /
          server: nfs-service.storage.svc.cluster.local
status:
  availableReplicas: 1
  conditions:
  - lastTransitionTime: 2018-12-07T11:42:45Z
    lastUpdateTime: 2018-12-07T11:42:45Z
    message: Deployment has minimum availability.
    reason: MinimumReplicasAvailable
    status: "True"
    type: Available
  - lastTransitionTime: 2018-12-07T11:40:31Z
    lastUpdateTime: 2018-12-07T11:48:08Z
    message: ReplicaSet "stash-demo-684cd86f7b" has successfully progressed.
    reason: NewReplicaSetAvailable
    status: "True"
    type: Progressing
  observedGeneration: 2
  readyReplicas: 1
  replicas: 1
  updatedReplicas: 1

Notice that stash-demo deployment has an init-container named stash which is running backup command.

Stash operator also has created a CronJob with name format stash-scaledown-cron-{restic-name}. Verify that the CronJob has been created successfully,

$ kubectl get cronjob -n demo
NAME                                  SCHEDULE    SUSPEND   ACTIVE   LAST SCHEDULE   AGE
stash-scaledown-cron-offline-restic   @every 5m   False     0        <none>          2m34s

Verify Backup:

Stash will create a Repository crd with name deployment.stash-demo for the respective repository during the first backup run. To verify, run the following command,

$  kubectl get repository deployment.stash-demo -n demo
NAME                    BACKUP-COUNT  LAST-SUCCESSFUL-BACKUP   AGE
deployment.stash-demo   1             2m                       2m

Here, BACKUP-COUNT field indicates number of backup snapshot has taken in this repository.

Cleaning up

To cleanup the Kubernetes resources created by this tutorial, run:

$ kubectl delete -n demo deployment stash-demo
$ kubectl delete -n demo secret local-secret
$ kubectl delete -n demo restic offline-restic
$ kubectl delete -n demo repository deployment.stash-demo

$ kubectl delete namespace demo

If you would like to uninstall Stash operator, please follow the steps here.

Next Steps

Learn how to use Stash to backup a Kubernetes deployment here.
Learn about the details of Restic CRD here.
To restore a backup see here.
Learn about the details of Recovery CRD here.
See the list of supported backends and how to configure them here.
See working examples for supported workload types here.
Thinking about monitoring your backup operations? Stash works out-of-the-box with Prometheus.
Learn about how to configure RBAC roles.

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