NFS client unable to connect

[xttjsn]

This might be a noob question, but I have two VMs running in the same bridged network. I configured VM1 as the NFS server:

$ sudo docker run \
-v /nfsroot:/nfsroot \
-v /etc/exports:/etc/exports:ro \
--cap-add SYS_ADMIN \
-p 2049:2049 \
--security-opt apparmor=erichough-nfs \
erichough/nfs-server

==================================================================
      SETTING UP ...
==================================================================
----> setup complete

==================================================================
      STARTING SERVICES ...
==================================================================
----> starting rpcbind
----> starting exportfs
----> starting rpc.mountd on port 32767
----> starting rpc.statd on port 32765 (outgoing from port 32766)
----> starting rpc.nfsd on port 2049 with 4 server thread(s)
----> all services started normally

==================================================================
      SERVER STARTUP COMPLETE
==================================================================
----> list of enabled NFS protocol versions: 4.2, 4.1, 4, 3
----> list of container exports:
---->   /nfsroot 10.0.0.0/24(ro,no_root_squash,no_subtree_check)
----> list of container ports that should be exposed:
---->   111 (TCP and UDP)
---->   2049 (TCP and UDP)
---->   32765 (TCP and UDP)
---->   32767 (TCP and UDP)

==================================================================
      READY AND WAITING FOR NFS CLIENT CONNECTIONS
==================================================================

Here's VM1's network status:

ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:76:8b:0e brd ff:ff:ff:ff:ff:ff
    inet 10.0.0.94/24 brd 10.0.0.255 scope global dynamic noprefixroute ens33
       valid_lft 594618sec preferred_lft 594618sec
...

VM2 will be using the interface ens33 at 10.0.0.94.

When I connect to the server using VM2, I get:

sudo mount 10.0.0.94:/nfsroot /mnt/shared_client
mount.nfs: requested NFS version or transport protocol is not supported

Some more verbose output:

$ sudo mount -v -t nfs -o vers=3,nfsvers=3 10.0.0.94:/nfsroot /mnt/shared_client
mount.nfs: timeout set for Sun Mar  8 17:34:18 2020
mount.nfs: trying text-based options 'vers=3,nfsvers=3,addr=10.0.0.94'
mount.nfs: prog 100003, trying vers=3, prot=6
mount.nfs: trying 10.0.0.94 prog 100003 vers 3 prot TCP port 2049
mount.nfs: prog 100005, trying vers=3, prot=17
mount.nfs: portmap query retrying: RPC: Program not registered
mount.nfs: prog 100005, trying vers=3, prot=6
mount.nfs: portmap query failed: RPC: Program not registered
mount.nfs: requested NFS version or transport protocol is not supported

$ sudo mount -v -t nfs -o vers=4,nfsvers=4 10.0.0.94:/nfsroot /mnt/shared_client
mount.nfs: timeout set for Sun Mar  8 17:34:53 2020
mount.nfs: trying text-based options 'vers=4,addr=10.0.0.94,clientaddr=192.168.117.129'
mount.nfs: mount(2): No such file or directory
mount.nfs: trying text-based options 'addr=10.0.0.94'
mount.nfs: prog 100003, trying vers=3, prot=6
mount.nfs: trying 10.0.0.94 prog 100003 vers 3 prot TCP port 2049
mount.nfs: prog 100005, trying vers=3, prot=17
mount.nfs: portmap query retrying: RPC: Program not registered
mount.nfs: prog 100005, trying vers=3, prot=6
mount.nfs: portmap query failed: RPC: Program not registered
mount.nfs: requested NFS version or transport protocol is not supported

Strangely, when I set up VM1's server by systemctl start nfs-kernel-server in the same network setup, VM2 CAN connect to the server without issue.

Am I missing anything?

[xttjsn]

It turns out that I only have to change /shared to / when doing mount:

sudo mount -v -t nfs -o vers=4,nfsvers=4 10.0.0.94:/ /mnt/shared_client      
mount.nfs: timeout set for Sun Mar  8 18:18:33 2020
mount.nfs: trying text-based options 'vers=4,addr=10.0.0.94,clientaddr=192.168.117.129'

[ehough]

Glad that you got it worked out and thank you for sharing your solution; hopefully it will help others.

NFSv4 uses a "pseudo filesystem" that causes widespread confusion wrt mount points. It's counter intuitive at best.