I figured out my problem- CentOS 7 was running “rpcbind” in its main scope (outside docker), but ECS’s Docker container runs its own version of rpcbind and ECS appears to communicate only with that one. The giveaway was running “rpcinfo -p” in the CentOS shell (not inside the docker container) and finding no NFS services.
To disable the CentOS global rpcbind process, “systemctl disable rpcbind” seems to do the trick. I shut down the docker and rebooted the CentOS VM for good measure, then after initialization I was able to mount it up (also reinstalled the whole ECS single-node instance before figuring that out):
root@apollo:~# mount -v ecs.lan:/spir/nfstest1/ /mnt2 -o vers=3,sec=sys,proto=tcp
mount.nfs: timeout set for Thu Feb 23 23:54:42 2017
mount.nfs: trying text-based options ‘vers=3,sec=sys,proto=tcp,addr=192.168.0.5’
mount.nfs: prog 100003, trying vers=3, prot=6
mount.nfs: trying 192.168.0.5 prog 100003 vers 3 prot TCP port 2049
mount.nfs: prog 100005, trying vers=3, prot=6
mount.nfs: trying 192.168.0.5 prog 100005 vers 3 prot TCP port 2049
root@apollo:~# df -k
Filesystem 1K-blocks Used Available Use% Mounted on
…
ecs.lan:/spir/nfstest1/ 4278190080 33029632 4245160448 1% /mnt2
When you have this set up correctly, running “rpcinfo -p” on the CentOS shell throws an error:
[root@ecs ~]# rpcinfo -p
rpcinfo: can’t contact portmapper: RPC: Remote system error – No such file or directory
But running rpcinfo -p inside a docker shell works, and port 111 is definitely listening:
[root@ecs ~]# docker exec -ti ecsstandalone /bin/bash
ecs:/ # rpcinfo -p
program vers proto port service
100000 4 tcp 111 portmapper
100000 3 tcp 111 portmapper
100000 2 tcp 111 portmapper
100000 4 udp 111 portmapper
100000 3 udp 111 portmapper
100000 2 udp 111 portmapper
100005 3 tcp 2049 mountd
100005 3 udp 2049 mountd
100003 3 tcp 2049 nfs
100024 1 tcp 2049 status
100021 4 tcp 10000 nlockmgr
100021 4 udp 10000 nlockmgr
ecs:/ # exit
exit
[root@ecs ~]# netstat -nap | grep ‘:111 ‘
tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN 9788/rpcbind
tcp6 0 0 :::111 :::* LISTEN 9788/rpcbind
udp 0 0 0.0.0.0:111 0.0.0.0:* 9788/rpcbind
udp6 0 0 :::111 :::* 9788/rpcbind