NFS fails to resolve hostname

I'm trying to create an NFS docker volume, however I'm unable to do so by hostname.

I'm creating the volume with:

sudo docker volume create --name foo_bar --driver local \
  --opt type=nfs4 \
  --opt o=addr=foo.lan.domain.xyz,rw,noatime,rsize=8192,wsize=8192,tcp,timeo=14 \
  --opt device=:/volume1/bar

However, when I try to create a docker container which uses this volume, I see:

docker: Error response from daemon: failed to mount local volume: mount :/volume1/bar:/var/lib/docker/volumes/foo_bar/_data, flags: 0x400, data: addr=foo.lan.domain.xyz,rsize=8192,wsize=8192,tcp,timeo=14: invalid argument.

The syslog shows:

kernel: [ 1662.349322] NFS: bad IP address specified: addr=foo.lan.domain.xyz

It seems that NFS is not attempting to resolve the domain name before connecting. This domain name is certainly valid.

$ host foo.lan.domain.xyz
foo.lan.domain.xyz has address 10.0.0.3

$ nslookup foo.lan.domain.xyz
Server:     127.0.0.53
Address:    127.0.0.53#53

Non-authoritative answer:
Name:   foo.lan.domain.xyz
Address: 10.0.0.3

$ showmount -e foo.lan.domain.xyz
Export list for foo.lan.domain.xyz:
/volume1/qux   lore.lan.domain.xyz

$ getent hosts 10.0.0.3
10.0.0.3        Bar.lan.domain.xyz

How can I get NFS to resolve this hostname? I'd really rather not hard code the IP address if it can be helped.

Solution 1:

I saw this because I was dealing with the same issue. I found some further information in the following two bugs

https://github.com/moby/moby/pull/27329

https://github.com/moby/moby/issues/31365

It turns out that docker is always expecting type=nfs and is expecting you to set the version by adding another option. Your command should be

sudo docker volume create --name foo_bar --driver local \
  --opt type=nfs \
  --opt o=addr=foo.lan.domain.xyz,rw,noatime,rsize=8192,wsize=8192,tcp,timeo=14,nfsvers=4 \
  --opt device=:/volume1/bar

You can verify which version the mount is using by executing this command while the container is running

sudo nfsstat -m