snapshots_clones

k8s Snapshots and Clones with Trident

Objective:
Kubernetes 1.17 promoted CSI Snapshots to Beta.
This is fully supported by Trident 20.01.1 and above.

In this task you will create a read-only snapshot of your PV and then also create a space-efficient read-write cloned PV from your snapshot. This type of task would be useful for application test and development or in environments that make use of CI/CD pipelines that require multiple persistent data copies for large development teams.

A. Prepare the environment

Ensure you are in the correct working directory by issuing the following command on your rhel3 putty terminal in the lab:

[root@rhel3 ~]# cd /root/netapp-bootcamp/trident_with_k8s/tasks/snapshots_clones/

We will create an app in its own namespace (also very useful for cleaning up everything when you are done).

[root@rhel3 ~]# kubectl create namespace ghost-snap-clone
namespace/ghost created

[root@rhel3 ~]# kubectl create -n ghost-snap-clone -f ghost.yaml
persistentvolumeclaim/blog-content created
deployment.apps/blog created
service/blog created

[root@rhel3 ~]# kubectl get all -n ghost-snap-clone
NAME                       READY   STATUS              RESTARTS   AGE
pod/blog-57d7d4886-5bsml   1/1     Running             0          50s

NAME           TYPE           CLUSTER-IP     EXTERNAL-IP          PORT(S)        AGE
service/blog   LoadBalancer   10.97.56.215   192.168.0.145        80:30070/TCP   50s

NAME                   READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/blog   1/1     1            1           50s

NAME                             DESIRED   CURRENT   READY   AGE
replicaset.apps/blog-57d7d4886   1         1         1       50s

[root@rhel3 ~]# kubectl get pvc,pv -n ghost-snap-clone
NAME                                 STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS        AGE
persistentvolumeclaim/blog-content   Bound    pvc-ce8d812b-d976-43f9-8320-48a49792c972   5Gi        RWX            sc-file-rwx         4m3s

NAME                                                        CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                                  STORAGECLASS        REASON   AGE
persistentvolume/pvc-ce8d812b-d976-43f9-8320-48a49792c972   5Gi        RWX            Delete           Bound    ghost-snap-clone/blog-content          sc-file-rwx                  4m2s

Check to see if you can access the app via your browser. In this example case, the LoadBalancer IP for our app is 192.168.0.145, though this may be different for you, so check your output from kubectl get all -n ghost-snap-clone.

B. Configure the snapshot feature

This link is a good read if you want to know more details about installing the CSI Snapshotter.

You first need to install 3 CRDs which you can find in the Kubernetes/CRD directory or in the CSI Snapshotter github repository.

[root@rhel3 ~]# kubectl create -f Kubernetes/CRD/
customresourcedefinition.apiextensions.k8s.io/volumesnapshotclasses.snapshot.storage.k8s.io created
customresourcedefinition.apiextensions.k8s.io/volumesnapshotcontents.snapshot.storage.k8s.io created
customresourcedefinition.apiextensions.k8s.io/volumesnapshots.snapshot.storage.k8s.io created

Then comes the Snapshot Controller, which is in the Kubernetes/Controller directory or in the CSI Snapshotter github repository.

[root@rhel3 ~]# kubectl create -f Kubernetes/Controller/
serviceaccount/snapshot-controller created
clusterrole.rbac.authorization.k8s.io/snapshot-controller-runner created
clusterrolebinding.rbac.authorization.k8s.io/snapshot-controller-role created
role.rbac.authorization.k8s.io/snapshot-controller-leaderelection created
rolebinding.rbac.authorization.k8s.io/snapshot-controller-leaderelection created
statefulset.apps/snapshot-controller created

Finally, you need to create a VolumeSnapshotClass object that points to the Trident driver.

[root@rhel3 ~]# kubectl create -f sc-volumesnapshot.yaml
volumesnapshotclass.snapshot.storage.k8s.io/csi-snap-class created

[root@rhel3 ~]# kubectl get volumesnapshotclass
NAME             DRIVER                  DELETIONPOLICY   AGE
csi-snap-class   csi.trident.netapp.io   Delete           3s

The volume snapshot feature is now ready to be tested.

C. Create a snapshot

Before you create your snapshot, let's make sure that you have some important data in your PV that we want to protect. Don't forget to use the blog-XXXXXXXX-XXXX pod name for your specific deployment. You can get this with the kubectl get -n ghost-snap-clone pod command.

[root@rhel3 ~]# kubectl exec -n ghost-snap-clone blog-5c9c4cdfbf-q986f -- touch content/very-important-file.txt

...and let's make sure the file is now there:

[root@rhel3 ~]# kubectl exec -n ghost-snapclone blog-5c9c4cdfbf-q986f -- ls -l content/very-important-file.txt
-rw-r--r--    1 root     root             0 Jun 30 11:34 /data/content/very-important-file.txt

Now that you have your important data in your PV, let's take a snapshot to protect it in case someone accidentally (or on purpose) deletes it:

[root@rhel3 ~]# kubectl create -n ghost-snap-clone -f pvc-snapshot.yaml
volumesnapshot.snapshot.storage.k8s.io/blog-snapshot created

Take a look at your snapshot status via kubectl:

[root@rhel3 ~]# kubectl get volumesnapshot -n ghost-snap-clone
NAME            READYTOUSE   SOURCEPVC      SOURCESNAPSHOTCONTENT   RESTORESIZE   SNAPSHOTCLASS    SNAPSHOTCONTENT                                    CREATIONTIME   AGE
blog-snapshot   true         blog-content                           5Gi           csi-snap-class   snapcontent-21331427-59a4-4b4a-a71f-91ffe2fb39bc   12m            12m

[root@rhel3 ~]# tridentctl -n trident get volume
+------------------------------------------+---------+-------------------+----------+--------------------------------------+--------+---------+
|                   NAME                   |  SIZE   |   STORAGE CLASS   | PROTOCOL |             BACKEND UUID             | STATE  | MANAGED |
+------------------------------------------+---------+-------------------+----------+--------------------------------------+--------+---------+
| pvc-b2113a4f-7359-4ab2-b771-a86272e3d11d | 5.0 GiB | sc-file-rwx       | file     | bdc8ce93-2268-4820-9fc5-45a8d9dead2a | online | true    |
+------------------------------------------+---------+-------------------+----------+--------------------------------------+--------+---------+

Take a look at your snapshot status via tridentctl:

[root@rhel3 ~]# tridentctl -n trident get snapshot
+-----------------------------------------------+------------------------------------------+
|                     NAME                      |                  VOLUME                  |
+-----------------------------------------------+------------------------------------------+
| snapshot-21331427-59a4-4b4a-a71f-91ffe2fb39bc | pvc-b2113a4f-7359-4ab2-b771-a86272e3d11d |
+-----------------------------------------------+------------------------------------------+

Your snapshot has been created!

E. Data Management with Snapshots

Now that you have an application with a PV and a Snapshot of that PV, what can you do with it? Below are 3 tasks that help to demonstrate the power of these mechanisms:

1. Create an instant Clone of your PV and perform a data-in-place application upgrade
2. Recover data from a Snapshot if someone accidentally (or on purpose) deletes anything
3. See the impact of deleting PVs, Snapshots or Clones when using these features

F. Cleanup

Make sure you are done with the 3 additional tasks above before you cleanup, otherwise you'll need to start this task over.

[root@rhel3 ~]# kubectl delete ns ghost-snap-clone
namespace "ghost-snap-clone" deleted

What's next

You can now move on to the last task on the production cluster:

• Dynamic export policy management

or jump ahead to the Development cluster tasks...

• Installing Trident

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