Lab 4: Dynamic NFS provisioning

In this Lab we will install, configure and test a dynamic NFS provisioner.

This is the easiest way of implementing dynamic provisioning into a cluster.

There are many more solutions:

• Rook/Ceph
• GlusterFS
• …

Prepare Minikube to run dynamic NFS provisioning

1. Install the NFS server into the VM

   sudo apt install nfs-kernel-server -y
      
      
   > Reading package lists... Done
   > Building dependency tree       
   > Reading state information... Done
   ...
   > Creating config file /etc/default/nfs-kernel-server with new version
   > Processing triggers for systemd (245.4-4ubuntu3) ...
   > Processing triggers for man-db (2.9.1-1) ...
   > Processing triggers for libc-bin (2.31-0ubuntu9) ...
   
   

   ``

2. Create the directory for NFS storage

   sudo mkdir -p /storage/nfs
   sudo chown -R nobody:nogroup /storage/nfs
   sudo chmod 777 /storage/nfs
   
   

   ``

   For production use, this directroy must be included in a backup strategy!

3. Make the NFS storage available

   echo "/storage/nfs *(rw,sync,no_root_squash,no_subtree_check)" | sudo tee --append /etc/exports
   sudo exportfs -a
   sudo systemctl restart nfs-kernel-server
   

   ``

   For this example we give full access to all IP addresses (*). For production use you should limit this!

4. Install the NFS client into the minikube VM

   minikube ssh "sudo apt update && sudo apt install nfs-common -y"
      
   > Get:1 http://archive.ubuntu.com/ubuntu eoan InRelease [255 kB]
   > Get:2 http://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable/xUbuntu_19.10  InRelease [1628 B]
   ...
   > running python post-rtupdate hooks for python3.7...
   > Processing triggers for libc-bin (2.30-0ubuntu2) ...
   > Processing triggers for systemd (242-7ubuntu3.7) ...
   
   

   ``

5. Make sure the minikube VM can access the NFS server on the host VM

   minikube ssh "echo '192.168.122.1   ubuntu' | sudo tee --append /etc/hosts"
   
   > 192.168.122.1   ubuntu
   

   ``

Create the dynamic provisioner

For this Lab we use the nfs-client dynamic provisioner from the kubernetes-incubator external-storage repository.

nfs-client is an automatic provisioner that uses existing and already configured NFS servers to support dynamic provisioning of Kubernetes Persistent Volumes via Persistent Volume Claims.

The Persistent volumes are provisioned as ${namespace}-${pvcName}-${pvName}.

You can find more information here: https://github.com/kubernetes-incubator/external-storage/tree/master/nfs-client

1. Create the NFS dynamic provisioner

   kubectl apply -f ~/training/volumes/nfs-provisioner.yaml
      
   > storageclass.storage.k8s.io/nfs-client created
   > serviceaccount/release-name-nfs-client-provisioner created
   > clusterrole.rbac.authorization.k8s.io/release-name-nfs-client-provisioner-runner created
   > clusterrolebinding.rbac.authorization.k8s.io/run-release-name-nfs-client-provisioner created
   > role.rbac.authorization.k8s.io/leader-locking-release-name-nfs-client-provisioner created
   > rolebinding.rbac.authorization.k8s.io/leader-locking-release-name-nfs-client-provisioner created
   > deployment.apps/release-name-nfs-client-provisioner created
   
   ...
   

   ``

2. Wait for the Pod to be in Ready state

   kubectl get pods
      
   > NAME                                                   READY   STATUS    RESTARTS   AGE
   > release-name-nfs-client-provisioner-59d648ddbf-gsv5w   1/1     Running   0          40m
   ...
   
   

   ``

3. Create a test PVC

   kind: PersistentVolumeClaim
   apiVersion: v1
   metadata:
     name: test-claim
   spec:
     storageClassName: nfs-client
     accessModes:
       - ReadWriteMany
     resources:
       requests:
         storage: 1Mi
   
   

   ``

   kubectl apply -f training/volumes/nfs-claim.yaml 
      
   > persistentvolumeclaim/test-claim created
   

   ``

4. Check that the PVC is bound

   kubectl get pvc
      
   > NAME             STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
   > test-claim       Bound    pvc-bc0a9cbf-69f0-4461-8ccb-bc5e48cb3201   1Mi        RWX            nfs-client     22s
   

   ``

Create the application

1. Create the Wordpress deployment

   kubectl apply -f training/volumes/nfs-wordpress.yaml
      
   > service/wordpress created
   > persistentvolumeclaim/wp-pv-claim created
   > deployment.apps/wordpress created
   

   ``

2. Create the MySQL deployment

   kubectl apply -f training/volumes/nfs-mysql.yaml 
      
   > service/wordpress-mysql created
   > persistentvolumeclaim/mysql-pv-claim created
   > deployment.apps/wordpress-mysql created
   

   ``

3. Wait for the Pods to be in Ready state

   kubectl get pods
      
   > NAME                                                   READY   STATUS    RESTARTS   AGE
   > wordpress-5b886cf59b-6bvgr                             1/1     Running   0          31m
   > wordpress-mysql-b9ddd6d4c-vjdhd                        1/1     Running   0          30m
   
   ...
   
   

   ``

4. Check that the PVC is bound

   kubectl get pvc
      
   > NAME             STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
   > mysql-pv-claim   Bound    pvc-fdd7df13-57b3-4661-b9c9-c27c63e2902e   20Gi       RWO            nfs-client     31m
   > wp-pv-claim      Bound    pvc-d80af17a-b0d8-4970-b521-a19400e18d0f   20Gi       RWO            nfs-client     32m
   ...
   

   ``

5. Open the app in Firefox

   minikube service wordpress
   

   ``

   kubectl delete deployment wordpress kubectl delete deployment wordpress-mysql

   kubectl apply -f training/volumes/nfs-mysql.yaml kubectl apply -f training/volumes/nfs-wordpress.yaml