Can not access docker from internet

I have built a cluster with three coreos bare-metal computers. Then I
use fleet to launch a docker to run ubuntu:14.04 and try to allow
somebody in another city to login.

The default ip address of
docker (interface docker0) is 172.17.x.x and this kind of private ip
address absolutely could not be accessed from Internet. I create a
docker network with public ip address and attach it to ubuntu container. But it still not work either.
coreos: 4.7.0
etcd2: 2.3.2
fleet: 0.11.7
docker: 1.10.3
Can someone meet the same problem and present some solution or suggestions?