How to set up an NFS server on a node in a kind cluster with overlayfs?

[ace0527]

I created a local kind cluster with two nodes on my macOS. I want to use one of the nodes (named as worker1) as an NFS server. On worker1, I installed the NFS-related components:

ii  libnfsidmap1:amd64            1:2.6.2-4+deb12u1              amd64        NFS idmapping library
ii  nfs-common                    1:2.6.2-4+deb12u1              amd64        NFS support files common to client and server
ii  nfs-kernel-server             1:2.6.2-4+deb12u1   

Then I exported the /mnt/nfs directory as an NFS directory:

# mkdir -p /mnt/nfs
# echo '/mnt/nfs *(rw,sync,no_subtree_check)' >> /etc/exports
# exportfs -a

However, I encountered an error when executing exportfs -a: the /mnt/nfs directory does not support NFS export.

exportfs: /mnt/nfs does not support NFS export

I found some information from internet indicating that NFS does not support the overlay file system, so I checked the file system type of the /mnt/nfs directory:

df -T /mnt/nfs
Filesystem     Type    1K-blocks     Used Available Use% Mounted on
overlay        overlay  61202244 23181440  34879480  40% /

It seems that the /mnt/nfs directory does not support NFS because its file system type is overlay.
So my questions are:

1. I don't know why the file system type of the /mnt/nfs directory is overlay. Does this have something to do with Docker's mechanism or the fact that I am using macOS?
2. As for the solution, is it enough to change the file system type of the /mnt/nfs directory to a type that NFS supports? How can I change the file system type of /mnt/nfs?"

[aojea]

It seems there are several tutorials out there using nfs succesfully, per example https://cloudyuga.guru/blogs/nfs-kind/, can you try following one of those and report back?

[ace0527]

It seems there are several tutorials out there using nfs succesfully, per example https://cloudyuga.guru/blogs/nfs-kind/, can you try following one of those and report back?

I tried the methods mentioned on the website, but they all failed due to overlayfs（just like mentioned in these two issues： nfs-ganesha/issues/511 , nfs-ganesha-server-and-external-provisioner/issues/45. I will later experiment on a Linux virtual machine instead of my macOS system to see if there will be different results.

[BenTheElder]

you can mount a path with https://kind.sigs.k8s.io/docs/user/configuration/#extra-mounts, so the filesystem is something else

https://github.com/kubernetes-sigs/nfs-ganesha-server-and-external-provisioner is testing with kind, and doesn't appear to be using any extra mounts though. AFAIK overlayfs can support nfs export: https://docs.kernel.org/filesystems/overlayfs.html#nfs-export

but this depends on the host.

[ace0527]

you can mount a path with https://kind.sigs.k8s.io/docs/user/configuration/#extra-mounts, so the filesystem is something else

https://github.com/kubernetes-sigs/nfs-ganesha-server-and-external-provisioner is testing with kind, and doesn't appear to be using any extra mounts though. AFAIK overlayfs can support nfs export: https://docs.kernel.org/filesystems/overlayfs.html#nfs-export

but this depends on the host.

Thank you for the info. I will search and try it out and feedback at some time.