Unable to replicate data using csi-driver-nfs

[bnaigaonkar]

What happened:
We have followed the steps as mentioned in CSI driver example.
Ref: https://github.com/kubernetes-csi/csi-driver-nfs/tree/master/deploy/example

I change the number of replicas in deployment (https://raw.githubusercontent.com/kubernetes-csi/csi-driver-nfs/master/deploy/example/deployment.yaml) from 1 to 2

While accessing NFS shared folder from each pod, we are getting new NFS folder mounted with no shared and replicated data.

What you expected to happen:
We are expecting that shared data should be mounted on each replica of the pod.
If I create files on one pod then it should be reflected on other pod through NFS server.

How to reproduce it:

1. Change the number of replicas in deployment (https://raw.githubusercontent.com/kubernetes-csi/csi-driver-
   nfs/master/deploy/example/deployment.yaml) from 1 to 2
2. Create files in pods
3. Check the new files on NFS server and other pod.

Anything else we need to know?:

Environment:

• CSI Driver version: CSI driver v4.8.0
• Kubernetes version (use kubectl version): v1.29.7
• OS (e.g. from /etc/os-release):
  PRETTY_NAME="Debian GNU/Linux 12 (bookworm)"
  NAME="Debian GNU/Linux"
  VERSION_ID="12"
  VERSION="12 (bookworm)"
  VERSION_CODENAME=bookworm
  ID=debian
  HOME_URL="https://www.debian.org/"
  SUPPORT_URL="https://www.debian.org/support"
  BUG_REPORT_URL="https://bugs.debian.org/"
• Kernel (e.g. uname -a): 6.1.0-23-cloud-amd64
• Install tools: MicroK8s v1.29.7 revision 7018
• Others: NA

[andyzhangx]

what's the result of mount | grep nfs if you exec into the nginx pod? @bnaigaonkar

[bnaigaonkar]

@andyzhangx Thank you .
Please find the result of mount | grep nfs command.

root@deployment-nfs-6bd697cb78-bcwfj:/# mount | grep nfs
/dev/nvme0n1p1 on /mnt/nfs type ext4 (rw,relatime,discard,errors=remount-ro)

root@deployment-nfs-6bd697cb78-bcwfj:/# df -h
Filesystem Size Used Avail Use% Mounted on
overlay 261G 140G 111G 56% /
tmpfs 64M 0 64M 0% /dev
/dev/nvme0n1p1 261G 140G 111G 56% /mnt/nfs
shm 64M 0 64M 0% /dev/shm
tmpfs 16G 12K 16G 1% /run/secrets/kubernetes.io/serviceaccount
tmpfs 7.8G 0 7.8G 0% /proc/acpi
tmpfs 7.8G 0 7.8G 0% /sys/firmware

[andyzhangx]

that means your nfs mount is broken, why it's mounted to /dev/nvme0n1p1? follow this guide to get csi driver logs on the node: https://github.com/kubernetes-csi/csi-driver-nfs/blob/master/docs/csi-debug.md#case2-volume-mountunmount-failed

# mount | grep nfs
/dev/nvme0n1p1 on /mnt/nfs type ext4 (rw,relatime,discard,errors=remount-ro)

[bnaigaonkar]

As per link https://github.com/kubernetes-csi/csi-driver-nfs/blob/master/docs/csi-debug.md#case2-volume-mountunmount-failed.

output is empty.
#kubectl exec -it csi-nfs-node-cvgbss -n kube-system -c nfs -- mount | grep nfs

I am getting empty output in pod with below command as well.
#mount | grep nfs

Please find below steps I have followed for the NFS mount.

Step 1:
I have set up a NFS Server on a Kubernetes cluster.
Ref: https://github.com/kubernetes-csi/csi-driver-nfs/blob/master/deploy/example/nfs-provisioner/README.md

Step 2:
Deploy the NFS CSI driver
Ref: install NFS CSI driver.

Step 3:
Storage Class Usage (Dynamic Provisioning)

Step 4:
kubectl create -f https://raw.githubusercontent.com/kubernetes-csi/csi-driver-nfs/master/deploy/example/pvc-nfs-csi-dynamic.yaml

Step 5:
kubectl create -f https://raw.githubusercontent.com/kubernetes-csi/csi-driver-nfs/master/deploy/example/deployment.yaml

[andyzhangx]

then what's the csi driver logs on that node:

kubectl logs csi-nfs-node-xxx -c nfs -n kube-system > csi-nfs-node.log

[bnaigaonkar]

csi-nfs-node.log
csi-nfs-node-description.log

Please find above log files for more details.

[bnaigaonkar]

Latest Update nfs mount inside driver: -

kubectl exec -it csi-nfs-node-cvgbss -n kube-system -c nfs -- mount | grep nfs

nfs-server.default.svc.cluster.local:/pvc-79d508c5-6e10-4c7c-a982-46c994a61142 on /var/snap/microk8s/common/var/lib/kubelet/pods/2beda551-3e7f-4907-baf4-5e6bb93815a3/volumes/kubernetes.io~csi/pvc-79d508c5-6e10-4c7c-a982-46c994a61142/mount type nfs4 (rw,relatime,vers=4.1,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=10.31.1.220,local_lock=none,addr=10.152.183.183)

[bnaigaonkar]

Latest Update nfs mount inside driver: -

kubectl exec -it csi-nfs-node-cvgbss -n kube-system -c nfs -- mount | grep nfs

nfs-server.default.svc.cluster.local:/pvc-79d508c5-6e10-4c7c-a982-46c994a61142 on /var/snap/microk8s/common/var/lib/kubelet/pods/2beda551-3e7f-4907-baf4-5e6bb93815a3/volumes/kubernetes.io~csi/pvc-79d508c5-6e10-4c7c-a982-46c994a61142/mount type nfs4 (rw,relatime,vers=4.1,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=10.31.1.220,local_lock=none,addr=10.152.183.183)

[bnaigaonkar]

As per observation communication between NFS-Server and NFS-Controller is fine.
Facing problem while mounting NFS share in pods, I was trying to mount nfs manually, but it didn't work. please find below details.

[andyzhangx]

from csi driver logs, the nfs mount succeeded:

 67  I0819 10:57:33.864134       1 utils.go:109] GRPC call: /csi.v1.Node/NodePublishVolume
    68  I0819 10:57:33.864159       1 utils.go:110] GRPC request: {"target_path":"/var/snap/microk8s/common/var/lib/kubelet/pods/2beda551-3e7f-4907-baf4-5e6bb93815a3/volumes/kubernetes.io~csi/pvc-79d508c5-6e10-4c7c-a982-46c994a61142/mount","volume_capability":{"AccessType":{"Mount":{"mount_flags":["nfsvers=4.1"]}},"access_mode":{"mode":5}},"volume_context":{"csi.storage.k8s.io/pv/name":"pvc-79d508c5-6e10-4c7c-a982-46c994a61142","csi.storage.k8s.io/pvc/name":"pvc-deployment-nfs","csi.storage.k8s.io/pvc/namespace":"default","server":"nfs-server.default.svc.cluster.local","share":"/","storage.kubernetes.io/csiProvisionerIdentity":"1724064909114-7957-nfs.csi.k8s.io","subdir":"pvc-79d508c5-6e10-4c7c-a982-46c994a61142"},"volume_id":"nfs-server.default.svc.cluster.local##pvc-79d508c5-6e10-4c7c-a982-46c994a61142##"}
    69  I0819 10:57:33.865693       1 nodeserver.go:132] NodePublishVolume: volumeID(nfs-server.default.svc.cluster.local##pvc-79d508c5-6e10-4c7c-a982-46c994a61142##) source(nfs-server.default.svc.cluster.local:/pvc-79d508c5-6e10-4c7c-a982-46c994a61142) targetPath(/var/snap/microk8s/common/var/lib/kubelet/pods/2beda551-3e7f-4907-baf4-5e6bb93815a3/volumes/kubernetes.io~csi/pvc-79d508c5-6e10-4c7c-a982-46c994a61142/mount) mountflags([nfsvers=4.1])
    70  I0819 10:57:33.865785       1 mount_linux.go:243] Detected OS without systemd
    71  I0819 10:57:33.865798       1 mount_linux.go:218] Mounting cmd (mount) with arguments (-t nfs -o nfsvers=4.1 nfs-server.default.svc.cluster.local:/pvc-79d508c5-6e10-4c7c-a982-46c994a61142 /var/snap/microk8s/common/var/lib/kubelet/pods/2beda551-3e7f-4907-baf4-5e6bb93815a3/volumes/kubernetes.io~csi/pvc-79d508c5-6e10-4c7c-a982-46c994a61142/mount)
    72  I0819 10:57:33.878479       1 nodeserver.go:149] skip chmod on targetPath(/var/snap/microk8s/common/var/lib/kubelet/pods/2beda551-3e7f-4907-baf4-5e6bb93815a3/volumes/kubernetes.io~csi/pvc-79d508c5-6e10-4c7c-a982-46c994a61142/mount) since mountPermissions is set as 0
    73  I0819 10:57:33.878535       1 nodeserver.go:151] volume(nfs-server.default.svc.cluster.local##pvc-79d508c5-6e10-4c7c-a982-46c994a61142##) mount nfs-server.default.svc.cluster.local:/pvc-79d508c5-6e10-4c7c-a982-46c994a61142 on /var/snap/microk8s/common/var/lib/kubelet/pods/2beda551-3e7f-4907-baf4-5e6bb93815a3/volumes/kubernetes.io~csi/pvc-79d508c5-6e10-4c7c-a982-46c994a61142/mount succeeded

[bnaigaonkar]

@andyzhangx yes, from csi driver logs, the nfs mount succeeded.
problem is that nfs share is not mounting in pods, I am getting permission denied error if I mount it manually.

[bnaigaonkar]

Workaround as explained kubernetes/minikube#3417

By adding nfs-service.default.svc.cluster.local and cluster IP address of nfs-server in /etc/hosts of node, I am able to mount the nfs-share in pods.
We need to add nfserver details in pv directly instead of storage class, so no need to create storage class for the same.

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