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RKE2 Troubleshooting: NFS Provisioner

Error Description​

The following error occurs when Kubernetes attempts to mount an NFS volume:

MountVolume.SetUp failed for volume "nfs-subdir-external-provisioner-root" : mount failed: exit status 32
Mounting command: mount
Mounting arguments: -t nfs 192.168.100.100:/volume1/rke2-pv /var/lib/kubelet/pods/b6ad96fb...
Output: mount: ... bad option; for several filesystems you might need a mount.<type> helper program.

This indicates that the node cannot mount the NFS directory.

1. Ensure NFS client tools are installed on worker nodes​

Different Linux distributions require different packages.

Ubuntu / Debian​

sudo apt-get update
sudo apt-get install -y nfs-common

CentOS / RHEL / Rocky / Alma​

sudo yum install -y nfs-utils

openSUSE / SLES​

sudo zypper install -y nfs-client

The node must contain mount.nfs. Missing tools will cause exit status 32.

2. Test manual mount on the worker node​

Run:

sudo mount -t nfs 192.168.100.100:/volume1/rke2-pv /mnt

If this fails, inspect kernel messages:

dmesg | tail

Common issues:

  • Permission denied
  • RPC service not running
  • Access denied by server

3. Verify Synology (or NFS server) configuration​

For Synology NAS:

  1. Enable NFS service
  2. Edit Shared Folder → NFS Permissions
  3. Add Kubernetes node subnet (e.g. 192.168.2.0/24)
  4. Squash: Map all users to admin (recommended for PV creation)
  5. Enable NFSv3 (some kubelet versions require it)
  6. Apply settings

4. Set required mount options (if needed)​

Some NFS servers require specifying the version explicitly.

For NFSv3:​

nfs:
  mountOptions:
    - nfsvers=3

For NFSv4.1:​

nfs:
  mountOptions:
    - nfsvers=4.1

5. Validate NFS server path and Helm chart values​

Ensure your values.yaml matches:

nfs:
  server: 192.168.100.100
  path: /volume1/rke2-pv

Errors in the path produce mount failures.

6. Check firewall ports​

NFS requires the following:

  • 111 (rpcbind)
  • 2049 (nfs)
  • 20048 (mountd)
  • Additional dynamic ports depending on configuration

Open these ports for Kubernetes nodes.

7. Check SELinux or AppArmor restrictions​

SELinux​

getenforce

If it's Enforcing, run:

sudo setsebool -P virt_use_nfs 1

AppArmor​

sudo aa-status | grep nfs

Profiles may block NFS mounting.

Summary of Common Causes​

  • Missing NFS client tools (nfs-common, nfs-utils)
  • Incorrect NFS permissions on Synology or server
  • Wrong export path
  • Required NFS version mismatch
  • Firewall blocking RPC/NFS ports
  • SELinux/AppArmor policies blocking mounts