Example Application Deployment

The following example walks through running a simple Nginx web server that leverages both the Cloud Controller Manager and Flexvolume Driver plugins through Kubernetes Services, Persistent Volumes, and Persistent Volume Claims.

Create an dynamic OCI Block Volume using a Kubernetes PersistentVolumeClaim

We'll start by creating a PersistentVolumeClaim (PVC). The cluster is integrated with the OCI Flexvolume Driver. As a result, creating a PVC will result in a block storage volume to (dynamically) be created in your tenancy.

Note that the matchLabels should contain the Availability Domain (AD) you want to provision a volume in, which should match the zone of at least one of your worker nodes:

$ kubectl describe nodes | grep zone
                    failure-domain.beta.kubernetes.io/zone=US-ASHBURN-AD-1
                    failure-domain.beta.kubernetes.io/zone=US-ASHBURN-AD-2

$ cat nginx-pvc.yaml

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: nginx-volume
spec:
  storageClassName: "oci"
  selector:
    matchLabels:
      oci-availability-domain: "US-ASHBURN-AD-1"
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 50Gi

To add the PersistentVolumeClaim, run the following:

$ kubectl apply -f nginx-pvc.yaml

After applying the PVC, you should see a block storage volume available in your OCI tenancy.

$ kubectl  get pv,pvc

Create a Kubernetes Deployment that references the PVC

Now you have a PVC, you can create a Kubernetes deployment that will consume the storage:

$ cat nginx-deployment.yaml

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: nginx
spec:
  replicas: 2
  template:
    metadata:
      labels:
        name: nginx
    spec:
      containers:
        - name: nginx
          image: nginx
          imagePullPolicy: IfNotPresent
          ports:
            - containerPort: 80
          volumeMounts:
            - name: nginx-storage
              mountPath: "/usr/share/nginx/html"
      volumes:
      - name: nginx-storage
        persistentVolumeClaim:
          claimName: nginx-volume

To run the deployment, run the following:

$ kubectl apply -f nginx-deployment.yaml

After applying the change, your pods should be scheduled on nodes running in the same AD of your volume and all have access to the shared volume:

$ kubectl get pods -o wide
NAME                     READY     STATUS    RESTARTS   AGE       IP           NODE
nginx-r1   1/1       Running   0          35s       10.99.46.4   k8s-worker-ad1-0.k8sworkerad1.k8soci.oraclevcn.com
nginx-r2   1/1       Running   0          35s       10.99.46.5   k8s-worker-ad1-0.k8sworkerad1.k8soci.oraclevcn.com

$ kubectl exec nginx-r1 touch /usr/share/nginx/html/test

$ kubectl exec nginx-r2 ls  /usr/share/nginx/html
test
lost+found

Expose the app using the Cloud Controller Manager

The cluster is integrated with the OCI Cloud Controller Manager (CCM). As a result, creating a service of type --type=LoadBalancer will expose the pods to the Internet using an OCI Load Balancer.

$ kubectl expose deployment nginx --port=80 --type=LoadBalancer

List service to get the external IP address (OCI LoadBalancer) of your exposed service. Note, the IP will be listed as <pending> while the load balancer is being provisioned:

$ kubectl get service nginx

Access the Nginx service

open http://<EXTERNAL-IP>:80

Clean up

Clean up the container, OCI Load Balancer, and Block Volume by deleting the deployment, service, and persistent volume claim:

$ kubectl delete service nginx

$ kubectl delete -f nginx-deployment.yaml

$ kubectl delete -f nginx-pvc.yaml