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.
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 4m2sCheck 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.
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 createdThen 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 createdFinally, 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 3sThe volume snapshot feature is now ready to be tested.
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.txtNow 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 createdTake 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!
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:
- Create an instant Clone of your PV and perform a data-in-place application upgrade
- Recover data from a Snapshot if someone accidentally (or on purpose) deletes anything
- See the impact of deleting PVs, Snapshots or Clones when using these features
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" deletedYou can now move on to the last task on the production cluster:
or jump ahead to the Development cluster tasks...
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