NFS Storage Service

Requirements

MultiNode Cluster	RAM	CPU	Disk	Network
2 Worker Nodes	4 GiB	4	250 GiB SSD	1Gbps Single
3+ Worker Nodes	8 GiB	4	500 GiB SSD	1Gbps Dual (Preferred)

Architecture

Install NFS server

Nfs Server is a dedicated Node outside the Kubernetes Cluster with dedicated storage and other specs as mentioned in the Requirements section.

to install the NFS server on Ubuntu based node, please follow these steps.

Update the repository

CODE

apt-get update

Install the required packages

CODE

sudo apt-get install nfs-kernel-server

Create the export directory

CODE

mkdir /srv/k8s

add the exported file-system to the NFS Server’s export list

CODE

vi /etc/exports

and add the line given below

CODE

/srv/k8s        WORKER_NODE1_IP(rw,async,no_subtree_check,no_root_squash,no_all_squash,insecure) WORKER_NODE2_IP(rw,async,no_subtree_check,no_root_squash,no_all_squash,insecure)  WORKER_NODE-N-IP(rw,async,no_subtree_check,no_root_squash,no_all_squash,insecure)

Please substitute the IP addresses for all the WORKER_NODE_IPs accordingly.

NOTE:

Be aware of the following points:
- there is no space between the IP address and the options
- you can list more IP addresses and options; they are space separated as in:
  - /export/users 192.168.1.1(rw,no_subtree_check) 192.168.1.2(rw,no_root_squash)
- using the insecure option allows clients such as Mac OS X to connect on ports above 1024. This option is not otherwise "insecure".
- Note that when locking down which clients can map an export by setting the IP address, you can either specify an address range using a subnet mask, or you can list a single IP address followed by the options. Using a subnet mask for single client's full IP address is **not** required. Just use something like 192.168.1.123(rw). There are a couple options for specifying the subnet mask. One style is 255.255.255.0. Both styles should work. The subnet mask marks which part of IP address must be evaluated.

Enable and start the NFS Server

CODE

systemctl enable --now  nfs-kernel-server.service

verify the exported file-system

CODE

exportfs -rav
showmount -e localhost

Kubernetes Worker Nodes

These steps should be performed on all the Worker nodes in the cluster

install the required package for nfs client

For Ubuntu:-

CODE

apt install -y nfs-common

For RHEL:-

CODE

sudo yum install -y nfs-utils

once the package is installed, you can verify the NFS mount point by running

CODE

mkdir /mnt/NFS
mount -t nfs NFS-SERVER_IP:/srv/k8s /mnt/NFS

If the above command runs succesfully, you will be able to write/create in /mnt/NFS directory

CODE

mkdir /mnt/NFS/${HOSTNAME}

verify the directory is created successfully on the NFS-SERVER by listing the contents of /srv/k8s/.

unmount the NFS mount point as we dont need it to be mounted consistently. the NFS driver will automatically mount relevant paths from within Worker Node in Kubernetes cluster.

CODE

umount /mnt/NFS

Prepare the kubernetes cluster for NFS Storage

For NFS Storage, we will be installing nfs-subdir-external-provisioner as volume provisioner for our Kubernetes cluster.

On Control-Plane

add the require helm repository

CODE

helm repo add nfs-subdir-external-provisioner https://kubernetes-sigs.github.io/nfs-subdir-external-provisioner/

refresh the help repo

CODE

helm repo update

install the helm chart

CODE

helm upgrade --install=true \
--namespace=nfs-client \
--create-namespace   \
--set replicaCount=5 \
--set storageClass.defaultClass=true \
--set storageClass.reclaimPolicy=Retain \
--set nfs.server=<NFS-SERVER-IP> \
--set nfs.path=<EXPORT_PATH>  \
nfs-subdir-external-provisioner \
nfs-subdir-external-provisioner/nfs-subdir-external-provisioner

Substitute the NFS-SERVER-IP and EXPORT_PATH with actual values

verify the deployment is ready by running

CODE

kubectl -n nfs-client get pods

Once all the pods are in running state, verify the current storage class assignment

CODE

kubectl get storageclass

expected output is something like

NONE

NAME                   PROVISIONER                                     RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
nfs-client (default)   cluster.local/nfs-subdir-external-provisioner   Retain          Immediate           true                   2d20h

Verify the NFS Storage Class

Deploy a test pod

deploy a test workload to verify the NFS storage class.

CODE

kubectl create -f https://raw.githubusercontent.com/kubernetes-sigs/nfs-subdir-external-provisioner/master/deploy/test-claim.yaml -f https://raw.githubusercontent.com/kubernetes-sigs/nfs-subdir-external-provisioner/master/deploy/test-pod.yaml

there should a PVC in Bound state to PV in nfs-client storage class

example output

CODE

kubectl  get pvc
NAME         STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
test-claim   Bound    pvc-4c922e69-bd8c-4835-bb6a-3b7d959e8e50   1Mi        RWX            nfs-client     2d18h

Teardown the test deployment

CODE

kubectl delete -f https://raw.githubusercontent.com/kubernetes-sigs/nfs-subdir-external-provisioner/master/deploy/test-claim.yaml -f https://raw.githubusercontent.com/kubernetes-sigs/nfs-subdir-external-provisioner/master/deploy/test-pod.yaml