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Version: 3.2

Cloud backups for a group of PVCs in OpenShift vSphere

Summary and Key concepts

Summary

This article provides instructions on how to create and manage group cloud snapshots of Portworx volumes in Kubernetes. It covers prerequisites such as installing Stork and configuring cloud credentials for connecting to cloud storage providers like S3. The article details the process of creating group cloud snapshots using the GroupVolumeSnapshot Custom Resource Definition (CRD), tracking the status of snapshots, and restoring data from snapshots. It also explains how to set pre- and post-snapshot rules and manage retries for failed snapshots. The guide includes an example of taking a group cloud snapshot of Cassandra PVCs and restoring the data in pods.

Kubernetes Concepts

  • PersistentVolumeClaim (PVC): Requests for storage in Kubernetes, which can be snapshotted and restored.
  • Annotations: Metadata used to manage group snapshots and specify cloud backup options.
  • Namespace: Used to isolate Kubernetes resources, and group snapshots can be restored across multiple namespaces.

Portworx Concepts

  • Stork: A Kubernetes extension for managing Portworx snapshots, backups, and restores.

  • GroupVolumeSnapshot: A Portworx CRD for taking snapshots of multiple PVCs as a group, including support for cloud backups.

  • VolumeSnapshot: A snapshot of a Portworx volume, which can be used for restoring data.

  • VolumeSnapshotRestore: A resource used for restoring volumes from snapshots, including in-place restores with Stork.

This document will show you how to create group cloud snapshots of Portworx volumes and how you can clone those snapshots to use them in pods.

Pre-requisites​

Installing Stork​

This requires that you already have Stork installed and running on your Kubernetes cluster. If you fetched the Portworx specs from the Portworx spec generator in Portworx Central and used the default options, Stork is already installed.

Configuring cloud secrets​

To create cloud snapshots, one needs to setup secrets with Portworx which will get used to connect and authenticate with the configured cloud provider.

Follow instructions on the create and configure credentials section to setup secrets.

Creating group cloud snapshots​

To take group snapshots, you need to use the GroupVolumeSnapshot CRD object and pass in portworx/snapshot-type as cloud. Here is a simple example:

apiVersion: stork.libopenstorage.org/v1alpha1
kind: GroupVolumeSnapshot
metadata:
  name: cassandra-group-cloudsnapshot
spec:
  pvcSelector:
    matchLabels:
      app: cassandra
  options:
    portworx/snapshot-type: cloud

Above spec will take a group snapshot of all PVCs that match labels app=cassandra.

The Examples section has a more detailed end-to-end example.

note

Above spec backs up the snapshots to a cloud S3 endpoint. If you intend on taking snapshots just local tot he cluster, refer to Create local group snapshots.

The GroupVolumeSnapshot object also supports specifying pre and post rules that are run on the application pods using the volumes being snapshotted. This allows users to quiesce the applications before the snapshot is taken and resume I/O after the snapshot is taken. Refer to 3D Snapshots for more detailed documentation on that.

Checking status of group cloud snapshots​

A new VolumeSnapshot object will get created for each PVC that matches the given pvcSelector. For example, if the label selector app: cassandra matches 3 PVCs, you will have 3 volumesnapshot objects.

You can track the status of the group volume snapshots using:

oc describe groupvolumesnapshot <group-snapshot-name>

This will show the latest status and will also list the VolumeSnapshot objects once it's complete. Below is an example of the status section of the cassandra group snapshot.

Status:
  Stage:   Final
  Status:  Successful
  Volume Snapshots:
    Conditions:
      Last Transition Time:  2019-01-14T20:30:49Z
      Message:               Snapshot created successfully and it is ready
      Reason:
      Status:                True
      Type:                  Ready
    Data Source:
      Portworx Volume:
        Snapshot Id:       xxxxxxxx-xxxx-xxxx-xxxx-4b6f09463a98/763613271174793816-922960401583326548
        Snapshot Type:     cloud
    Parent Volume ID:      763613271174793816
    Task ID:               xxxxxxxx-xxxx-xxxx-xxxx-66490f4172c7
    Volume Snapshot Name:  cassandra-group-cloudsnapshot-cassandra-data-cassandra-2-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
    Conditions:
      Last Transition Time:  2019-01-14T20:30:49Z
      Message:               Snapshot created successfully and it is ready
      Reason:
      Status:                True
      Type:                  Ready
    Data Source:
      Portworx Volume:
        Snapshot Id:       xxxxxxxx-xxxx-xxxx-xxxx-4b6f09463a98/1081147806034223862-518034075073409747
        Snapshot Type:     cloud
    Parent Volume ID:      1081147806034223862
    Task ID:               xxxxxxxx-xxxx-xxxx-xxxx-b62951dcca0e
    Volume Snapshot Name:  cassandra-group-cloudsnapshot-cassandra-data-cassandra-0-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
    Conditions:
      Last Transition Time:  2019-01-14T20:30:49Z
      Message:               Snapshot created successfully and it is ready
      Reason:
      Status:                True
      Type:                  Ready
    Data Source:
      Portworx Volume:
        Snapshot Id:       xxxxxxxx-xxxx-xxxx-xxxx-4b6f09463a98/237262101530372284-299546281563771622
        Snapshot Type:     cloud
    Parent Volume ID:      237262101530372284
    Task ID:               xxxxxxxx-xxxx-xxxx-xxxx-ee3b13f7c03f
    Volume Snapshot Name:  cassandra-group-cloudsnapshot-cassandra-data-cassandra-1-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
  • You can see 3 volume snapshots which are part of the group snapshot. The name of the volume snapshot is in the Volume Snapshot Name field. For more details on the volumesnapshot, you can do:

oc get volumesnapshot.volumesnapshot.external-storage.k8s.io/<volume-snapshot-name> -o yaml

Retries of group cloud snapshots​

If a cloud groupvolumesnapshot fails to trigger, it will be retried. However, by default, if a cloud groupvolumesnapshot fails after it has been triggered/started successfully, it will be marked as Failed and will not be retried

If you want to change this behavior, you can set the maxRetries field in the spec. In below example, we will perform 3 retries on failures.

apiVersion: stork.libopenstorage.org/v1alpha1
kind: GroupVolumeSnapshot
metadata:
  name: cassandra-group-cloudsnapshot
spec:
  pvcSelector:
    matchLabels:
      app: cassandra
  maxRetries: 3
  options:
    portworx/snapshot-type: cloud

When maxRetries are enabled, NumRetries in the status of the groupvolumesnapshot will indicate the number of retries performed.

Snapshots across namespaces​

When creating a group snapshot, you can specify a list of namespaces to which the group snapshot can be restored. Below is an example of a group cloud snapshot which can be restored into prod-01 and prod-02 namespaces.

apiVersion: stork.libopenstorage.org/v1alpha1
kind: GroupVolumeSnapshot
metadata:
  name: cassandra-groupsnapshot
spec:
  pvcSelector:
    matchLabels:
      app: cassandra
  options:
    portworx/snapshot-type: cloud
  restoreNamespaces:
   - prod-01
   - prod-02

Restoring from group cloud snapshots​

Previous section describes how to list the volume snapshots that are part of a group snapshot. Once you have the names the VolumeSnapshot objects, you can use them to create PVCs from them.

When you perform an in-place restore to a PVC, Stork takes the pods using that PVC offline, restores the volume from the snapshot, then brings the pods back online.

note

In-place restore using VolumeSnapshotRestore works only for applications deployed using the stork scheduler. If you're not using the Stork scheduler, Portworx displays the following error when describing the VolumeSnapshotRestore resource:

Events:
  Type     Reason  Age               From   Message
  ----     ------  ----              ----   -------
  Warning  Failed  5s (x2 over 15s)  stork  application not scheduled by stork scheduler

  1. Create a VolumeSnapshotRestore YAML file specifying the following:

    • apiVersion as stork.libopenstorage.org/v1alpha1
    • kind as VolumeSnapshotRestore
    • metadata.name with the name of the object that performs the restore
    • metadata.namespace with the name of the target namespace
    • spec.sourceName with the name of the snapshot you want to restore
    • spec.sourceNamespace with the namespace in which the snapshot resides

    The following example restores data from a snapshot called mysql-snapshot which was created in the mysql-snap-restore-splocal namespace to a PVC called mysql-snap-inrestore in the default namespace:

    apiVersion: stork.libopenstorage.org/v1alpha1
    kind: VolumeSnapshotRestore
    metadata:
      name: mysql-snap-inrestore
      namespace: default
    spec:
      sourceName: mysql-snapshot
      sourceNamespace: mysql-snap-restore-splocal

  2. Place the spec into a file called mysql-cloud-snapshot-restore.yaml and apply it:

    oc apply -f mysql-cloud-snapshot-restore.yaml

  3. You can enter the following command to see the status of the restore process:

    storkctl get volumesnapshotrestore
    NAME                   SOURCE-SNAPSHOT   SOURCE-SNAPSHOT-NAMESPACE   STATUS          VOLUMES   CREATED
    mysql-snap-inrestore   mysql-snapshot    default                     Successful      1         23 Sep 19 21:55 EDT

    You can also use the oc describe command to retrieve more detailed information about the status of the restore process. Example:

    oc describe volumesnapshotrestore mysql-snap-inrestore

    Name:         mysql-snap-inrestore
    Namespace:    default
    Labels:       <none>
    Annotations:  kubectl.kubernetes.io/last-applied-configuration:
                    {"apiVersion":"stork.libopenstorage.org/v1alpha1","kind":"VolumeSnapshotRestore","metadata":{"annotations":{},"name":"mysql-snap-inrestore...
    API Version:  stork.libopenstorage.org/v1alpha1
    Kind:         VolumeSnapshotRestore
    Metadata:
      Creation Timestamp:  2019-09-23T17:24:30Z
      Generation:          5
      Resource Version:    904014
      Self Link:           /apis/stork.libopenstorage.org/v1alpha1/namespaces/default/volumesnapshotrestores/mysql-snap-inrestore
      UID:                 xxxxxxxx-xxxx-xxxx-xxxx-000c295d6364
    Spec:
      Group Snapshot:    false
      Source Name:       mysql-snapshot
      Source Namespace:  default
    Status:
      Status:  Successful
      Volumes:
        Namespace:  default
        Pvc:        mysql-data
        Reason:     Restore is successful
        Snapshot:   k8s-volume-snapshot-xxxxxxxx-xxxx-xxxx-xxxx-320ff611f4ca
        Status:     Successful
        Volume:     pvc-xxxxxxxx-xxxx-xxxx-xxxx-000c295d6364
    Events:
      Type    Reason      Age   From   Message
      ----    ------      ----  ----   -------
      Normal  Successful  0s    stork  Snapshot in-Place  Restore completed

When you install Stork, it also creates a storage class called stork-snapshot-sc. This storage class can be used to create PVCs from snapshots.

To create a PVC from a snapshot, add the snapshot.alpha.kubernetes.io/snapshot annotation to refer to the snapshot name. If the snapshot exists in another namespace, you should specify the snapshot namespace with the stork.libopenstorage.org/snapshot-source-namespace annotation in the PVC.

The Retain policy is important if you need to keep the volume in place, even after removing the Kubernetes objects from a cluster.

note
  • As shown in the following example, the storageClassName should be the Stork StorageClass stork-snapshot-sc.
  • When using this storage class the PVC is creating with delete as Retain policy. However, if the source PVC is having the policy as retain, then this will not be inherited to the restored PVC. After the restore, you should manually verify the retain policy and change it if needed.
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-snap-clone
  annotations:
    snapshot.alpha.kubernetes.io/snapshot: mysql-snapshot
spec:
  accessModes:
     - ReadWriteOnce
  storageClassName: stork-snapshot-sc
  resources:
    requests:
      storage: 2Gi

Once you apply the above spec, you will see a PVC created by Stork. This PVC will be backed by a Portworx volume clone of the snapshot created above.

oc get pvc

NAMESPACE   NAME                                   STATUS    VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS                AGE
default     mysql-data                             Bound     pvc-xxxxxxxx-xxxx-xxxx-xxxx-0214683e8447   2Gi        RWO            px-mysql-sc                 2d
default     mysql-snap-clone                       Bound     pvc-xxxxxxxx-xxxx-xxxx-xxxx-0214683e8447   2Gi        RWO            stork-snapshot-sc           2s

Examples​

Group cloud snapshot for all cassandra PVCs​

In below example, we will take a group snapshot for all PVCs in the default namespace and that have labels app: cassandra and back it up to the configured cloud S3 endpoint in the Portworx cluster.

Step 1: Deploy cassandra statefulset and PVCs​

Following spec creates a replica 3 cassandra statefulset. Each replica pod will use its own PVC.

##### Portworx storage class
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: portworx-repl2
provisioner: pxd.portworx.com
parameters:
  repl: "2"
---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: cassandra
  name: cassandra
spec:
  clusterIP: None
  ports:
    - port: 9042
  selector:
    app: cassandra

---

apiVersion: "apps/v1"
kind: StatefulSet
metadata:
  name: cassandra
spec:
  selector:
    matchLabels:
      app: cassandra
  serviceName: cassandra
  replicas: 3
  template:
    metadata:
      labels:
        app: cassandra
    spec:
      containers:
      - name: cassandra
        image: gcr.io/google-samples/cassandra:v12
        imagePullPolicy: Always
        ports:
        - containerPort: 7000
          name: intra-node
        - containerPort: 7001
          name: tls-intra-node
        - containerPort: 7199
          name: jmx
        - containerPort: 9042
          name: cql
        resources:
          limits:
            cpu: "500m"
            memory: 1Gi
          requests:
           cpu: "500m"
           memory: 1Gi
        securityContext:
          capabilities:
            add:
              - IPC_LOCK
        lifecycle:
          preStop:
            exec:
              command: ["/bin/sh", "-c", "PID=$(pidof java) && kill $PID && while ps -p $PID > /dev/null; do sleep 1; done"]
        env:
          - name: MAX_HEAP_SIZE
            value: 512M
          - name: HEAP_NEWSIZE
            value: 100M
          - name: CASSANDRA_SEEDS
            value: "cassandra-0.cassandra.default.svc.cluster.local"
          - name: CASSANDRA_CLUSTER_NAME
            value: "K8Demo"
          - name: CASSANDRA_DC
            value: "DC1-K8Demo"
          - name: CASSANDRA_RACK
            value: "Rack1-K8Demo"
          - name: CASSANDRA_AUTO_BOOTSTRAP
            value: "false"
          - name: POD_IP
            valueFrom:
              fieldRef:
                fieldPath: status.podIP
          - name: POD_NAMESPACE
            valueFrom:
              fieldRef:
                fieldPath: metadata.namespace
        readinessProbe:
          exec:
            command:
            - /bin/bash
            - -c
            - /ready-probe.sh
          initialDelaySeconds: 15
          timeoutSeconds: 5
        # These volume mounts are persistent. They are like inline claims,
        # but not exactly because the names need to match exactly one of
        # the stateful pod volumes.
        volumeMounts:
        - name: cassandra-data
          mountPath: /cassandra_data
  # These are converted to volume claims by the controller
  # and mounted at the paths mentioned above.
  volumeClaimTemplates:
  - metadata:
      name: cassandra-data
      labels:
        app: cassandra
      annotations:
        volume.beta.kubernetes.io/storage-class: portworx-repl2
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 2Gi

Step 2: Wait for all cassandra pods to be running​

List the cassandra pods:

oc get pods -l app=cassandra

NAME          READY     STATUS    RESTARTS   AGE
cassandra-0   1/1       Running   0          3m
cassandra-1   1/1       Running   0          2m
cassandra-2   1/1       Running   0          1m

Once you see all the 3 pods, you can also list the cassandra PVCs.

oc get pvc -l app=cassandra

NAME                         STATUS    VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS        AGE
cassandra-data-cassandra-0   Bound     pvc-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7   2Gi        RWO            stork-snapshot-sc   3m
cassandra-data-cassandra-1   Bound     pvc-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7   2Gi        RWO            stork-snapshot-sc   2m
cassandra-data-cassandra-2   Bound     pvc-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7   2Gi        RWO            stork-snapshot-sc   1m

Step 3: Take the group cloud snapshot​

Apply the following spec to take the cassandra group snapshot. Portworx will quiesce I/O on all volumes before triggering their snapshots.

apiVersion: stork.libopenstorage.org/v1alpha1
kind: GroupVolumeSnapshot
metadata:
  name: cassandra-group-cloudsnapshot
spec:
  pvcSelector:
    matchLabels:
      app: cassandra
  options:
    portworx/snapshot-type: cloud

Once you apply the above object you can check the status of the snapshots using oc:

oc describe groupvolumesnapshot cassandra-group-cloudsnapshot

While the group snapshot is in progress, the status will reflect as InProgress. Once complete, you should see a status stage as Final and status as Successful.

Name:         cassandra-group-cloudsnapshot
Namespace:    default
Labels:       <none>
Annotations:  kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"stork.libopenstorage.org/v1alpha1","kind":"GroupVolumeSnapshot","metadata":{"annotations":{},"name":"cassandra-group-cloudsnapshot","nam...
API Version:  stork.libopenstorage.org/v1alpha1
Kind:         GroupVolumeSnapshot
Metadata:
  Cluster Name:
  Creation Timestamp:  2019-01-14T20:30:13Z
  Generation:          0
  Resource Version:    18212101
  Self Link:           /apis/stork.libopenstorage.org/v1alpha1/namespaces/default/groupvolumesnapshots/cassandra-group-cloudsnapshot
  UID:                 xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
Spec:
  Options:
    Portworx / Snapshot - Type:  cloud
  Post Snapshot Rule:
  Pre Snapshot Rule:
  Pvc Selector:
    Match Labels:
      App:  cassandra
Status:
  Stage:   Final
  Status:  Successful
  Volume Snapshots:
    Conditions:
      Last Transition Time:  2019-01-14T20:30:49Z
      Message:               Snapshot created successfully and it is ready
      Reason:
      Status:                True
      Type:                  Ready
    Data Source:
      Portworx Volume:
        Snapshot Id:       xxxxxxxx-xxxx-xxxx-xxxx-4b6f09463a98/763613271174793816-922960401583326548
        Snapshot Type:     cloud
    Parent Volume ID:      763613271174793816
    Task ID:               xxxxxxxx-xxxx-xxxx-xxxx-66490f4172c7
    Volume Snapshot Name:  cassandra-group-cloudsnapshot-cassandra-data-cassandra-2-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
    Conditions:
      Last Transition Time:  2019-01-14T20:30:49Z
      Message:               Snapshot created successfully and it is ready
      Reason:
      Status:                True
      Type:                  Ready
    Data Source:
      Portworx Volume:
        Snapshot Id:       xxxxxxxx-xxxx-xxxx-xxxx-4b6f09463a98/1081147806034223862-518034075073409747
        Snapshot Type:     cloud
    Parent Volume ID:      1081147806034223862
    Task ID:               xxxxxxxx-xxxx-xxxx-xxxx-b62951dcca0e
    Volume Snapshot Name:  cassandra-group-cloudsnapshot-cassandra-data-cassandra-0-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
    Conditions:
      Last Transition Time:  2019-01-14T20:30:49Z
      Message:               Snapshot created successfully and it is ready
      Reason:
      Status:                True
      Type:                  Ready
    Data Source:
      Portworx Volume:
        Snapshot Id:       xxxxxxxx-xxxx-xxxx-xxxx-4b6f09463a98/237262101530372284-299546281563771622
        Snapshot Type:     cloud
    Parent Volume ID:      237262101530372284
    Task ID:               xxxxxxxx-xxxx-xxxx-xxxx-ee3b13f7c03f
    Volume Snapshot Name:  cassandra-group-cloudsnapshot-cassandra-data-cassandra-1-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
Events:                    <none>

Above we can see that creation of cassandra-group-snapshot created 3 volumesnapshots:

  1. cassandra-group-cloudsnapshot-cassandra-data-cassandra-0-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
  2. cassandra-group-cloudsnapshot-cassandra-data-cassandra-1-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
  3. cassandra-group-cloudsnapshot-cassandra-data-cassandra-2-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7

These correspond to the PVCs cassandra-data-cassandra-0, cassandra-data-cassandra-1 and cassandra-data-cassandra-2 respectively.

You can also describe these individual volume snapshots using

oc describe volumesnapshot cassandra-group-cloudsnapshot-cassandra-data-cassandra-0-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7

Name:         cassandra-group-cloudsnapshot-cassandra-data-cassandra-0-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
Namespace:    default
Labels:       <none>
Annotations:  <none>
API Version:  volumesnapshot.external-storage.k8s.io/v1
Kind:         VolumeSnapshot
Metadata:
  Cluster Name:
  Creation Timestamp:  2019-01-14T20:30:49Z
  Owner References:
    API Version:     stork.libopenstorage.org/v1alpha1
    Kind:            GroupVolumeSnapshot
    Name:            cassandra-group-cloudsnapshot
    UID:             xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
  Resource Version:  18212097
  Self Link:         /apis/volumesnapshot.external-storage.k8s.io/v1/namespaces/default/volumesnapshots/cassandra-group-cloudsnapshot-cassandra-data-cassandra-0-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
  UID:               xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
Spec:
  Persistent Volume Claim Name:  cassandra-data-cassandra-0
  Snapshot Data Name:            cassandra-group-cloudsnapshot-cassandra-data-cassandra-0-xxxxxxxx-xxxx-xxxx-xxxx-080027ee1df7
Status:
  Conditions:
    Last Transition Time:  2019-01-14T20:30:49Z
    Message:               Snapshot created successfully and it is ready
    Reason:
    Status:                True
    Type:                  Ready
  Creation Timestamp:      <nil>
Events:                    <none>

Deleting group snapshots​

To delete group snapshots, you need to delete the GroupVolumeSnapshot that was used to create the group snapshots. Stork will delete all other volumesnapshots that were created for this group snapshot.

oc delete groupvolumesnapshot cassandra-group-cloudsnapshot

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