Add example blueprint for CSI snapshot functions (#1184)

* style: Add CSI Snapshot funcs MySQL example blueprint

* style: Updates in the example README

* style: Update title

* style: typo in Prerequisites

* style: Fix multiple typos

* style: Update helm command

* style: Fix title, blueprint note and 'Backup application data' descripion

* style: Remove unnecessary quotation marks

* style: Update blueprint note

* fix: Update create blueprint command

* style: fix grammatical typos and readme header syntax

* style: Fix create blueprint note with correct blueprint file name

* style: Update README as per reviewer comments

* style: Explain --pvc argument

* style: Update introduction as per reviewer comment

* Update example README as per reviewer comments

* Update KubeOps function to allow create & delete for core group resources

* Add test case for KubeOps Delete core group resource

* Remove core group permissions from clusterrole

* Update KubeOps Delete operation to wait for resource to be deleted

* Update testcase for kubeops delete on core group resource

* Update KubeOps test to use existing svc spec

* Update poll.Wait logic for waiting on delete operation to complete

* Fix gofmt issues

* Update wait.Poll to poll.Wait method & pass context from parent

* Update as per reviewer comments

* Update example with Time Log application

* Replace namespace mysql with time-log

* Handle error from Delete() and add comment for using poll.Wait()

* Add waitForResourceDeletion function

* Remove redundant check for error

* Revert createPhase method in kubeops_test.go

* Update KubeOps test

* Update README as per reviewer comments

* Add comment to explain the waitForResourceDeletion function

* Update comment for waitForResourceDeletion

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
Co-authored-by: Pavan Navarathna <pavan@kasten.io>

examples/stable/csi-snapshot/README.md

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+# Backup and restore using CSI VolumeSnapshot
+
+## Introduction
+VolumeSnapshots provide Kubernetes users with a standardized way to copy a volume's contents at a particular point in time without creating an entirely new volume. This functionality enables, for example, database administrators to backup databases before performing edit or delete modifications.
+This example demonstrates Kanister's ability to protect an application called Time-Logger using CSI VolumeSnapshots. Time-Logger application is contrived but useful for demonstrating Kanister's features. The application appends the current time to a log file every second.
+
+## Prerequisites
+
+- Helm 3 installed
+- Kubernetes 1.16+ with Beta APIs enabled
+- Kanister controller version 0.72.0 installed in the cluster, let's assume in namespace `kanister`
+- Kanctl CLI installed (https://docs.kanister.io/tooling.html#install-the-tools)
+- VolumeSnapshot CRDs, Snapshot Controller & a CSI Driver
+
+## Install application
+
+Install Time-Logger application.
+
+```bash
+# Create namespace
+$ kubectl create namespace time-log
+
+# Create the Deployment and PersistentVolumeClaim in time-log namespace
+$ kubectl -n time-log create -f ./examples/time-log/time-logger-deployment.yaml
+
+# Run a shell inside time-logger deployment's pod
+$ kubectl exec -it $(kubectl get pods -n time-log -l app=time-logger -o=jsonpath='{.items[0].metadata.name}') -n time-log -- /bin/bash
+
+# Make note of the first entry recorded in the /var/log/time.log
+$ head --lines=1 /var/log/time.log
+Sun Jan 23 08:54:39 UTC 2022
+```
+
+## Protect the Application
+
+### Create Blueprint
+
+Create the Blueprint in `kanister` namespace
+
+> **Note**:  This example uses a Kubernetes cluster on DigitalOcean. Therefore the `snapshotClass` and `storageClass` in the following `./examples/stable/csi-snapshot/csi-snapshot-blueprint.yaml` file are set to `do-block-storage`. Change the arguments appropriately before creating the blueprint.
+
+```bash
+$ kubectl create -f ./examples/stable/csi-snapshot/csi-snapshot-blueprint.yaml -n kanister
+```
+
+### Backup the application data
+
+Create a snapshot of application data using `backup` action defined in blueprint. One of the easiest ways to do so is by using `kanctl` utility.
+
+```bash
+# Create Actionset
+# Make sure the value of blueprint matches the name of blueprint created earlier
+
+$ kanctl create actionset --action backup --namespace kanister --blueprint csi-snapshot-bp --deployment time-log/time-logger
+actionset backup-mlvcv created
+
+$ kubectl --namespace kanister get actionset
+NAME                         AGE
+backup-mlvcv                 112s
+
+# View the status of the actionset
+# Make sure the name of the actionset here matches the name of the actionset created above
+$ kubectl --namespace kanister describe actionset backup-mlvcv
+
+# Check the CSI VolumeSnapshot created
+$ kubectl -n time-log get volumesnapshot
+NAME                          READYTOUSE   SOURCEPVC      SOURCESNAPSHOTCONTENT   RESTORESIZE   SNAPSHOTCLASS            SNAPSHOTCONTENT                               CREATIONTIME   AGE
+time-log-pvc-snapshot-nxj4g   true         time-log-pvc                           1Gi           do-block-storage   snapcontent-13bc2d1c-6717-47a2-a0b7-4a2f76bd2cb4   58s            58s
+```
+
+## Disaster strikes!
+
+Let's say someone accidentally deleted the log file at path `/var/log`
+
+```bash
+# Run a shell inside time-logger deployment's pod
+$ kubectl exec -it $(kubectl get pods -n time-log -l app=time-logger -o=jsonpath='{.items[0].metadata.name}') -n time-log -- /bin/bash
+
+# Remove the log file
+$ rm /var/log/time.log
+
+# Check the first entry recorded in the /var/log/time.log again. It is now replaced with a new entry.
+# This is because Time-Logger app recreates the log file once it's deleted and starts adding newer entries to it.
+$ head --lines=1 /var/log/time.log
+Sun Jan 23 09:15:43 UTC 2022
+```
+
+## Restore application
+
+Use the backup created earlier to restore the application data. This can be achieved using `kanctl` again by creating the restore action.
+
+```bash
+# Make sure to use correct backup actionset name here
+$ kanctl --namespace kanister create actionset --action restore --from backup-mlvcv
+actionset restore-backup-mlvcv-6z9xn created
+
+# Use the following command to check events in the actionset
+$ kubectl --namespace kanister describe actionset restore-backup-mlvcv-6z9xn
+```
+
+## Verify the restored application data
+
+To verify restore action, check the first entry of the file `/var/log/time.log` and confirm that it's been restored with the original value.
+
+```bash
+# Run a shell inside time-logger deployment's pod
+$ kubectl exec -it $(kubectl get pods -n time-log -l app=time-logger -o=jsonpath='{.items[0].metadata.name}') -n time-log -- /bin/bash
+
+$ head --lines=1 /var/log/time.log
+Sun Jan 23 08:54:39 UTC 2022
+```
+
+## Delete the Artifacts
+
+The CSI VolumeSnapshot created by the backup action can be cleaned up using the following command.
+
+```bash
+# Make sure to use correct backup actionset name here
+$ kanctl --namespace kanister create actionset --action delete --from backup-mlvcv
+actionset delete-backup-mlvcv-cq6bw created
+
+# View the status of the ActionSet
+$ kubectl --namespace kanister describe actionset delete-backup-glptq-cq6bw
+```
+
+## Cleanup
+
+### Uninstalling the application
+
+To uninstall the application delete `time-log` namespace.
+
+```bash
+# Remove time-log namespace
+$ kubectl delete namespace time-log
+```
+
+### Delete CRs
+
+Remove the blueprint.
+
+```bash
+$ kubectl delete blueprints.cr.kanister.io csi-snapshot-bp -n kanister
+```
+
+Remove the actionsets.
+
+```bash
+$ kubectl delete actionsets -n kanister --all
+```

examples/stable/csi-snapshot/csi-snapshot-blueprint.yaml

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+apiVersion: cr.kanister.io/v1alpha1
+kind: Blueprint
+metadata:
+  name: csi-snapshot-bp
+actions:
+  backup:
+    outputArtifacts:
+      snapshotInfo:
+        keyValue:
+          name: "{{ .Phases.createCSISnapshot.Output.name }}"
+          pvc: "{{ .Phases.createCSISnapshot.Output.pvc }}"
+          namespace: "{{ .Phases.createCSISnapshot.Output.namespace }}"
+          restoreSize: "{{ .Phases.createCSISnapshot.Output.restoreSize }}"
+          snapshotContent: "{{ .Phases.createCSISnapshot.Output.snapshotContent }}"
+    phases:
+    - func: CreateCSISnapshot
+      name: createCSISnapshot
+      args:
+        pvc: "{{ (index .Object.spec.template.spec.volumes 0).persistentVolumeClaim.claimName }}"
+        namespace: "{{ .Object.metadata.namespace }}"
+        snapshotClass: do-block-storage
+  restore:
+    inputArtifactNames:
+    - snapshotInfo
+    phases:
+    - func: ScaleWorkload
+      name: scaleDownSS
+      args:
+        name: "{{ .Deployment.Name }}"
+        namespace: "{{ .Deployment.Namespace }}"
+        kind: deployment
+        replicas: 0
+    - func: KubeOps
+      name: deleteOriginalPVC
+      args:
+        operation: delete
+        namespace: "{{ .ArtifactsIn.snapshotInfo.KeyValue.namespace }}"
+        objectReference:
+          apiVersion: v1
+          group: ""
+          resource: persistentvolumeclaims
+          name: "{{ .ArtifactsIn.snapshotInfo.KeyValue.pvc }}"
+          namespace: "{{ .ArtifactsIn.snapshotInfo.KeyValue.namespace }}"
+    - func: RestoreCSISnapshot
+      name: restorePVCFromSnapshot
+      args:
+        name: "{{ .ArtifactsIn.snapshotInfo.KeyValue.name }}"
+        pvc: "{{ .ArtifactsIn.snapshotInfo.KeyValue.pvc }}"
+        namespace: "{{ .ArtifactsIn.snapshotInfo.KeyValue.namespace }}"
+        storageClass: do-block-storage
+        restoreSize: "{{ .ArtifactsIn.snapshotInfo.KeyValue.restoreSize }}"
+        accessModes: ["ReadWriteOnce"]
+        volumeMode: "Filesystem"
+    - func: ScaleWorkload
+      name: scaleUpSS
+      args:
+        name: "{{ .Deployment.Name }}"
+        namespace: "{{ .Deployment.Namespace }}"
+        kind: deployment
+        replicas: 1
+  delete:
+    inputArtifactNames:
+    - snapshotInfo
+    phases:
+    - func: DeleteCSISnapshot
+      name: deleteCSISnapshot
+      args:
+        name: "{{ .ArtifactsIn.snapshotInfo.KeyValue.name }}"
+        namespace: "{{ .ArtifactsIn.snapshotInfo.KeyValue.namespace }}"