nfs-subdir-external-provisioner

Deploy kubernetes-sigs/nfs-subdir-external-provisioner to provide a RWX storage class based on an existing NFS server.

Requirements

An available NFS server

See nfs-server for test purpose or www.digitalocean.com - How To Set Up an NFS Mount on Ubuntu 22.04 for classic installation with nfs-kernel-server

Parameters

Name	Description	Default
`NFS_SERVER_IP`	IP of the NFS server	`nfs-server.nfs-system.svc.cluster.local` (1)
`NFS_PATH`	Path to the export	`/` (2)

(1) See Troubleshooting (2) Use export with fsid=0 in /etc/exports on NFS server

Usage with Kubernetes

Deploy nfs-server or adapt params to use an existing NFS server :

# Ex with nfs-server on vagrantbox-1
# (https://github.com/mborne/k3s-deploy)
export NFS_SERVER_IP=192.168.50.201
export NFS_PATH=/

Read k8s-install.sh and run :

bash k8s-install.sh

# check nfs-subdir-external-provisioner deployment status (READY 1/1)
kubectl -n nfs-system get deployment

# ensure that storageclass is defined
kubectl get storageclass

See nfs-demo for an example using the "nfs" StorageClass

Troubleshooting

DNS resolution from node

With NFS_SERVER_IP=nfs-server.nfs-system.svc.cluster.local, you may face name resolution issues especially with kind :

Unable to attach or mount volumes: unmounted volumes=[nfs-subdir-external-provisioner-root], unattached volumes=[kube-api-access-p2vmw nfs-subdir-external-provisioner-root]: timed out waiting for the condition

Use the following workaround if nodes are not configured to invoke embedded DNS to resolve .cluster.local IP's :

export NFS_SERVER_IP=$(kubectl -n nfs-system get svc/nfs-server -o jsonpath='{.spec.clusterIP}')
export NFS_PATH=/
bash nfs-subdir-external-provisioner/k8s-install.sh

IP stability

Note that NFS_SERVER_IP will be present in PersistentVolume definitions and that the corresponding IP is resolved at mount time if a domain name is provided.

Using something like NFS_SERVER_IP=dns-server.priv.example.com and ensuring stability NFS server IP is probably a good idea to avoid problems.

Resources