I just created a core container, and I cannot get it to connect to my NFS share. 

root@emby:~# mount -v -t nfs 10.0.1.100:/mnt/RAID /mnt/RAID
mount.nfs4: timeout set for Thu Apr 14 15:51:38 2016
mount.nfs4: trying text-based options 'addr=10.0.1.100,clientaddr=10.0.1.132'
mount.nfs4: mount(2): Permission denied 

The wierd thing is, if I build a VM using the core iso to install onto the hard drive, nfs works great.

root@core:~# uname -a
Linux core 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt20-1+deb8u4 (2016-02-29) x86_64 GNU/Linux
root@core:~# mount -v -t nfs4 10.0.1.100:/mnt/RAID /mnt/RAID
mount.nfs4: timeout set for Thu Apr 14 21:04:42 2016
mount.nfs4: trying text-based options 'addr=10.0.1.100,clientaddr=10.0.1.133'
root@core:~# mount
10.0.1.100:/mnt/RAID on /mnt/RAID type nfs4 (rw,relatime,vers=4.0,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=10.0.1.133,local_lock=none,addr=10.0.1.100)
root@core:~#

Is there something preventing containers from using nfs?