How-to: Install NFS Client Provisioner and use NFS as persistent storage for on-premise Oracle Linux and Kubernetes deployments
In this How-to guide I’ll describe the configuration steps to setup the NFS Client Provisioner on an Oracle Linux on-premise Kubernetes cluster. The provisioner automatically creates persistent volumes in Kubernetes for an external, already configured NFS server.
I use this configuration in Kubernetes demos, workshops or even in small proof of concept installations where you want to have a quick installation experience. But do not hesitate to use this How-to guide for bare-metal or other virtual deployments.
Prerequisites
I run this deployment on a laptop using Vagrant and VirtualBox. I follow the standard installation as published on the Oracle Community website: Use Vagrant and VirtualBox to setup Oracle Container Services for use with Kubernetes. Here’s my Kubernetes cluster:
# kubectl get nodes
NAME STATUS ROLES AGE VERSION
master.vagrant.vm Ready master 43h v1.12.5+2.1.1.el7
worker1.vagrant.vm Ready <none> 42h v1.12.5+2.1.1.el7
worker2.vagrant.vm Ready <none> 42h v1.12.5+2.1.1.el7
You must have an already configured NFS server in your network and you should know the IP_address of the server and the exported mountpath for the NFS share. If you do not have an external NFS server, try to setup NFS services on your Kubernetes master node that we use for this demo (for test and demo purposes only). In this How-to guide I use:
Server: 192.168.99.100
Mountpath: /export/kubernetes/devtest
In this Howto-guide we use the Kubernetes Helm package-manager, please make sure to follow Oracle Linux Helm installation steps as described in this Helm Howto-guide.
Install NFS Client Provisioner
The NFS Client Provisioner is a Kubernetes application to dynamically create persistent volumes for your applications. The NFS share is provided by an already existing NFS server outside your Kubernetes deployment.
First, on each Oracle Linux worker node, install the NFS packages:
# yum install -y nfs-utils
The Helm NFS Provisioner chart requires some configuration settings so that your Kubernetes server knows how to find your external NFS server and mountpath. For this I use a customized yaml file to overwrite the default settings.
# wget https://raw.githubusercontent.com/jromers/k8s-ol-howto/master/nfs-client/values-nfs-client.yaml
# more values-nfs-client.yaml
replicaCount: 2
nfs:
server: 192.168.99.100
path: /export/kubernetes/devtest
mountOptions:
storageClass:
archiveOnDelete: false
Change the server and path settings in the values-nfs-client.yaml file to the NFS server and mountpath you use in your infrastructure. This configuration uses two Replicas and when an applications is deleted with Helm it also removes the files from the NFS store. If you want to keep the data after the application is removed set archiveOnDelete to true.
Install the provisioner:
# helm install --name ext -f values-nfs-client.yaml stable/nfs-client-provisioner
# kubectl get storageclass
NAME PROVISIONER AGE
nfs-client cluster.local/ext-nfs-client-provisioner 3m
# kubectl get pods
NAME READY STATUS RESTARTS AGE
ext-nfs-client-provisioner-6fcf996c79-5svck 1/1 Running 0 4m
ext-nfs-client-provisioner-6fcf996c79-wcp57 1/1 Running 0 4m
For the sake of simplicity, I did not pay much attention to the NFS permissions. In real production environments you should set proper UID and GID mappings between containers and NFS share.
On my NFS server (with /export/kubernetes/devtest) I have the following directory permissions:
# ls -l /export/kubernetes/
total 4
drwxr-xr-x 4 nfsnobody nfsnobody 4096 Dec 18 22:17 devtest