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05-storage.md

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Kubernetes storage (PV and PVC):

List the available storage classes:

kubectl get storageclass

Create a claim for a dynamically provisioned volume (PVC) for nginx.

$ kubectl create -f support-files/pvc-nginx.yaml

Check that the PVC exists and is bound:

$ kubectl get pvc

Example:

$ kubectl get pvc
NAME        STATUS    VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
pvc-nginx   Bound     pvc-e8a4fc89-2bae-11e8-b065-42010a8400e3   5Gi        RWO            standard       4m

There should be a corresponding auto-created persistent volume (PV) against this PVC:

$ kubectl get pv
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS    CLAIM               STORAGECLASS   REASON    AGE
pvc-e8a4fc89-2bae-11e8-b065-42010a8400e3   5Gi        RWO            Delete           Bound     default/pvc-nginx   standard                 5m

We are going to use the file support-files/nginx-persistent-storage.yaml file to use storage/volume directives:

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      volumes:
      - name: nginx-htmldir-volume
        persistentVolumeClaim:
          claimName: pvc-nginx
      containers:
      - name: nginx
        image: nginx:1.9.1
        ports:
        - containerPort: 443
        - containerPort: 80
        volumeMounts:
        - mountPath: "/usr/share/nginx/html"
          name: nginx-htmldir-volume

Deploy nginx again.

$ kubectl create -f support-files/nginx-persistent-storage.yaml

After it starts, you may want to examine it by using kubectl describe pod nginx and look out for volume declarations.

Now, you access the Nginx instance using curl. You should get a "403 Forbidden", because now the volume you mounted is empty.

Hint. You learned about exposing deployments on the network in the service discovery exercise.

Try to reach the nginx pod by executing a bash shell inside a multitool pod.

Hint. You learned about the multitool and running command inside a container pod in the service discovery exercise.

$ kubectl exec -it multitool-<ID> bash
bash-4.4# curl 10.0.96.7
<html>
<head><title>403 Forbidden</title></head>
<body bgcolor="white">
<center><h1>403 Forbidden</h1></center>
<hr><center>nginx/1.9.1</center>
</body>
</html>
bash-4.4#

Exit the multitool pod again.

Create a file in the htmldir inside the nginx pod and add some text in it:

$ kubectl exec -it nginx-deployment-6665c87fd8-cc8k9 -- bash

root@nginx-deployment-6665c87fd8-cc8k9:/# echo "<h1>Welcome to Nginx</h1>This is Nginx with html directory mounted as a volume from GCE Storage."  > /usr/share/nginx/html/index.html
root@nginx-deployment-6665c87fd8-cc8k9:/#

Exit the nginx pod again. From the multitool container, run curl again, you should see the web page:

$ kubectl exec -it multitool-69d6b7fc59-gbghn bash

bash-4.4#
 curl 10.0.96.7
<h1>Welcome to Nginx</h1>This is Nginx with html directory mounted as a volume from GCE Storage.
bash-4.4#

Kill the pod:

$ kubectl delete pod nginx-deployment-6665c87fd8-cc8k9
pod "nginx-deployment-6665c87fd8-cc8k9" deleted

Check if it is up (notice a new pod):

$ kubectl get pods -o wide
NAME                                READY     STATUS    RESTARTS   AGE       IP          NODE
multitool-69d6b7fc59-gbghn          1/1       Running   0          10m       10.0.97.8   gke-dcn-cluster-2-default-pool-4955357e-txm7
nginx-deployment-6665c87fd8-nh7bs   1/1       Running   0          1m        10.0.96.8   gke-dcn-cluster-2-default-pool-4955357e-8rnp

Again, from multitool, curl the new nginx pod. You should see the page you created in previous step:

$ kubectl exec -it multitool-69d6b7fc59-gbghn bash
bash-4.4# curl 10.0.96.8
<h1>Welcome to Nginx</h1>This is Nginx with html directory mounted as a volume from GCE Storage.
bash-4.4#

Clean up

$ kubectl delete deployment multitool
$ kubectl delete deployment nginx-deployment
$ kubectl delete service nginx-deployment
$ kubectl delete pvc pvc-nginx