The purpose of this lab is to demonstrate how you can request storage from OpenShift and have it attach to your application.
Containers, by design, are ephemeral. In short, if you want your application to store persistent data; you will need to attach to a backend storage system.
In this Lab, we will be:
-
Deploying an application that takes uploads
-
Upload a File, and delete the pod
-
Attach persistant storage
-
Upload a File, and delete the pod
NOTE: Storage provisioning must be setup by the Operations Team before proceeding.
Step 1: Deploy Application
Create a project called storage-UserName and deploy the application
oc new-project storage-UserName --description="My Storage-project" --display-name="Storage Project" oc new-app php~https://github.com/RedHatWorkshops/openshift-php-upload-demo
Once the application is deployed expose the route
$ oc get svc NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE openshift-php-upload-demo 172.30.212.62 <none> 8080/TCP 2m $ oc expose svc openshift-php-upload-demo route "openshift-php-upload-demo" exposed
Visit your application; it should look like this
Step 2: Test with ephemeral storage
Pick a file to upload and upload it to the app. Once uploaded you can view
a list of file when you click List Uploaded Files. It should look something
like this
You can see where the uploaded files are if you use oc rsh. They are uploaded
under /opt/app-root/src/uploaded
$ oc get pods NAME READY STATUS RESTARTS AGE openshift-php-upload-demo-1-build 0/1 Completed 0 10m openshift-php-upload-demo-1-rdktr 1/1 Running 0 5m $ oc rsh openshift-php-upload-demo-1-rdktr sh-4.2$ ls -1 /opt/app-root/src/uploaded shadowman.png sh-4.2$ exit
Delete this pod.
$ oc delete pod openshift-php-upload-demo-1-rdktr pod "openshift-php-upload-demo-1-rdktr" deleted
Now login to your new pod that got spun up. Your data is gone!
$ oc get pods NAME READY STATUS RESTARTS AGE openshift-php-upload-demo-1-build 0/1 Completed 0 13m openshift-php-upload-demo-1-wnv4r 1/1 Running 0 38s $ oc rsh openshift-php-upload-demo-1-wnv4r sh-4.2$ ls -1 /opt/app-root/src/uploaded sh-4.2$ exit
Step 3: Requesting Storage
In OpenShift, Storage is abstracted out to where one simply "requests" storage and it’s up to the backend adminsitrator to provide the solution
On the webconsole on the left side navigation click on "Storage". It will bing you to the storage overview page.
On the right hand side; click the "Create Storage" button. This will take you to the "Create Storage" page.
Here you need to enter the following
* Storage Class: <provided by your instructor> * Name: myclaim * Access Mode: Shared Access (RWX) * Size: 1 GiB
The Storage Class will be given to you by your instructor. The Name must be
unique to the project namespace. The Access Mode means "how many apps can access
this storage". For block storage you’d choose Singe User (RWO); in this instance
we are choosing Shared Access (RWX) (for File based storage like NFS). The Size
is set to 1 GB just for testing.
Once you click on "Create" it’ll go from a Pending stage to Bound. You can see
this on the command-line as well by checking your pvc (Which stands for Persistant
Volume Claim)
$ oc get pvc NAME STATUS VOLUME CAPACITY ACCESSMODES AGE myclaim Bound pvc-071ee3ef-86d2-11e7-aec4-52540019c877 1Gi RWX 27s
Get yourself familair with the configuration
$ oc get pvc myclaim -o yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
annotations:
pv.kubernetes.io/bind-completed: "yes"
pv.kubernetes.io/bound-by-controller: "yes"
volume.beta.kubernetes.io/storage-class: glusterfs-storage
volume.beta.kubernetes.io/storage-provisioner: kubernetes.io/glusterfs
creationTimestamp: 2017-08-22T00:37:07Z
name: myclaim
namespace: storage-UserName
resourceVersion: "48898"
selfLink: /api/v1/namespaces/testing-user00/persistentvolumeclaims/myclaim
uid: 071ee3ef-86d2-11e7-aec4-52540019c877
spec:
accessModes:
- ReadWriteMany
resources:
requests:
storage: 1Gi
volumeName: pvc-071ee3ef-86d2-11e7-aec4-52540019c877
status:
accessModes:
- ReadWriteMany
capacity:
storage: 1Gi
phase: Bound
We will now bind this storage to the application’s path of where it is
storing the files. This is under /opt/app-root/src/uploaded. You need
to add the volume to the deploymentConfig of openshift-php-upload-demo.
$ oc volume dc/openshift-php-upload-demo --add -t pvc --claim-name=myclaim --mount-path=/opt/app-root/src/uploaded info: Generated volume name: volume-c7jtb deploymentconfig "openshift-php-upload-demo" updated
Step 3: Testing Configuration
This will trigger a new deployment. Login to your pod to see the mount.
$ oc get pods NAME READY STATUS RESTARTS AGE openshift-php-upload-demo-1-build 0/1 Completed 0 1h openshift-php-upload-demo-8-16dzg 1/1 Running 0 1m $ oc rsh openshift-php-upload-demo-8-16dzg sh-4.2$ df -h /opt/app-root/src/uploaded/ Filesystem Size Used Avail Use% Mounted on 172.16.1.11:vol_464dc941ae641d2693b1382cc221a0b5 1016M 33M 983M 4% /opt/app-root/src/uploaded
Upload a file like before. Once uploaded; delete the pod
$ oc get pods NAME READY STATUS RESTARTS AGE openshift-php-upload-demo-1-build 0/1 Completed 0 1h openshift-php-upload-demo-8-16dzg 1/1 Running 0 2m $ oc delete pod openshift-php-upload-demo-8-16dzg pod "openshift-php-upload-demo-8-16dzg" deleted
Log into the newly spunup pod and verify that your file is still there!
$ oc get pods NAME READY STATUS RESTARTS AGE openshift-php-upload-demo-1-build 0/1 Completed 0 1h openshift-php-upload-demo-8-4brh0 1/1 Running 0 58s $ oc rsh openshift-php-upload-demo-8-4brh0 sh-4.2$ ls -1 /opt/app-root/src/uploaded/ shadowman.png
In this lab you learned how to request, attach, and test persistant storage.