doc: add nfs-provisioner docs

hack/verify-yamllint.sh

@@ -6,7 +6,7 @@ fi
 
 LOG=/tmp/yamllint.log
 
-for path in "flexvolume/smb/*.yaml" "flexvolume/smb/deployment/*.yaml" "flexvolume/blobfuse/*.yaml" "flexvolume/blobfuse/deployment/*.yaml" "local/*.yaml"
+for path in "flexvolume/smb/*.yaml" "flexvolume/smb/deployment/*.yaml" "flexvolume/blobfuse/*.yaml" "flexvolume/blobfuse/deployment/*.yaml" "local/*.yaml" "nfs/*.yaml"
 do
     echo "checking yamllint under path: $path ..."
     yamllint -f parsable $path | grep -v "line too long" > $LOG

nfs/README.md

@@ -0,0 +1,65 @@
+# Use NFS Server Provisioner on AKS
+[NFS Server Provisioner](https://github.com/kubernetes-incubator/external-storage/tree/master/nfs) is an out-of-tree dynamic provisioner for Kubernetes. You can use it to quickly & easily deploy shared storage that works almost anywhere. This doc shows how to set up NFS Server Provisioner on AKS using [NFS Server Provisioner helm chart](https://github.com/helm/charts/tree/master/stable/nfs-server-provisioner), the NFS server data is stored on single Azure managed disk. To get high availability, you may use [Rook](https://github.com/rook/rook), step-by-step doc: [Using Rook / Ceph with PVCs on Azure Kubernetes Service](https://partlycloudy.blog/2019/12/08/using-rook-ceph-with-pvcs-on-azure-kubernetes-service/).
+ 
+### 1. Install nfs-server-provisioner helm chart
+ - following example would provision 100GB storage(one data disk) on an agent node, serving as a NFSv3 server
+```console
+helm repo add stable https://kubernetes-charts.storage.googleapis.com/
+helm install stable/nfs-server-provisioner --generate-name --set=persistence.storageClass=default,persistence.enabled=true,persistence.size=100Gi
+```
+
+### 2. After installation successfully, a new storage class `nfs` created
+```console
+# kubectl describe sc nfs
+Name:                  nfs
+IsDefaultClass:        No
+Annotations:           <none>
+Provisioner:           cluster.local/nfs-server-provisioner-1587007822
+Parameters:            <none>
+AllowVolumeExpansion:  True
+MountOptions:
+  vers=3
+ReclaimPolicy:      Delete
+VolumeBindingMode:  Immediate
+Events:             <none>
+```
+
+### Example#1: create a statefulset with NFS volume mount
+```console
+kubectl create -f https://raw.githubusercontent.com/Azure/kubernetes-volume-drivers/master/nfs/statefulset-nfs.yaml
+```
+
+ - enter the pod container to validate
+```console
+# kubectl exec -it statefulset-nfs-0 bash
+root@statefulset-nfs-0:/# df -h
+Filesystem                                                    Size  Used Avail Use% Mounted on
+overlay                                                        97G   11G   87G  11% /
+tmpfs                                                          64M     0   64M   0% /dev
+tmpfs                                                         3.4G     0  3.4G   0% /sys/fs/cgroup
+10.0.212.68:/export/pvc-c08bb76e-6d45-452a-8333-53b13bd01000   99G   60M   99G   1% /mnt/nfs
+/dev/sda1                                                      97G   11G   87G  11% /etc/hosts
+...
+```
+
+### Example#2: set up wordpress based on NFS server
+```console
+helm repo add bitnami https://charts.bitnami.com/bitnami
+helm install --set persistence.storageClass="nfs" --generate-name bitnami/wordpress
+```
+ - check wordpress pods status
+```
+# kubectl get po
+NAME                                    READY   STATUS    RESTARTS   AGE
+nfs-server-provisioner-1587040611-0     1/1     Running   0          15m
+wordpress-1587040914-5659b7f8db-xl44v   1/1     Running   1          10m
+wordpress-1587040914-mariadb-0          1/1     Running   0          10m
+```
+
+ - nfs server performance in writing small files scenario
+```console
+time ( wget -qO- https://wordpress.org/latest.tar.gz | tar xvz -C /mnt/nfs )
+real    0m16.286s
+user    0m0.429s
+sys     0m1.214s
+```

nfs/statefulset-nfs.yaml

@@ -0,0 +1,40 @@
+---
+apiVersion: apps/v1
+kind: StatefulSet
+metadata:
+  name: statefulset-nfs
+  labels:
+    app: nginx
+spec:
+  serviceName: statefulset-nfs
+  replicas: 3
+  template:
+    metadata:
+      labels:
+        app: nginx
+    spec:
+      containers:
+        - name: statefulset-nfs
+          image: nginx
+          command:
+            - "/bin/sh"
+            - "-c"
+            - while true; do echo $(date) >> /mnt/nfs/outfile; sleep 1; done
+          volumeMounts:
+            - name: persistent-storage
+              mountPath: /mnt/nfs
+  updateStrategy:
+    type: RollingUpdate
+  selector:
+    matchLabels:
+      app: nginx
+  volumeClaimTemplates:
+    - metadata:
+        name: persistent-storage
+        annotations:
+          volume.beta.kubernetes.io/storage-class: nfs
+      spec:
+        accessModes: ["ReadWriteMany"]
+        resources:
+          requests:
+            storage: 10Gi