I created a CentOS 7 docker container in which I want to mount a NFS share in. Said share is owned by user virtual with uid 1200. So I
do some exporting (docker container is in 172.17.0.0/16):

spindizzy> cat /etc/exports
/export 10.0.0.0/24(ro,fsid=0,no_subtree_check,sync)
172.17.0.0/16(ro,fsid=0,no_subtree_check,sync)
[…]
/export/mail 172.17.0.0/16(rw,root_squash,no_subtree_check,sync)
spindizzy>

and then some mounting:

bash-4.2# id virtual uid00(virtual) gid00(virtual) groups00(virtual)
bash-4.2# nfsstat -m bash-4.2# mount.nfs4 -v -o proto=tcp fileserver.in.kushana.com:mail
/var/spool/vmail mount.nfs4: timeout set for Wed Oct 8 03:11:43 2014
mount.nfs4: trying text-based options
‘proto=tcp,addr.0.0.18,clientaddr2.17.0.29’
bash-4.2# nfsstat -m
/var/spool/vmail from fileserver.in.kushana.com://mail Flags: rw,relatime,vers=4.0,rsize1072,wsize1072,namlen%5,hard,proto=tcp,timeo`0,retrans=2,sec=sys,clientaddr2.17.0.29,local_lock=none,addr.0.0.18

bash-4.2# ls -l /var/spool/
total 12
drwxr-xr-x 2 root root 4096 Jun 10 01:11 lpd drwxrwxr-x 2 root mail 4096 Oct 8 02:15 mail drwxr-xr-x 2 4294967294 4294967294 4096 Oct 3 17:34 vmail bash-4.2#

And am getting the famous share being mounted as nobody issue. In the client (docker container), I went in /etc/idmapd.conf and set the Domain to be the domain where the NFS server is at (in.kushana.com). Now, how do I restart idmapd? It is a systemd service
(/usr/lib/systemd/system/rpcidmapd.service, which uses
/etc/sysconfig/nfs).