We came to install Docker on CentOS easily. Here is an instruction for the way to expose Docker remote API port on CentOS.
$ cat /etc/sysconfig/docker other_args=""
Edit the file
/etc/sysconfig/docker as below.
other_args="-H tcp://0.0.0.0:4243 -H unix:///var/run/docker.sock"
After that, restart docker and try to access the host from another host.
$ sudo /etc/init.d/docker restart ... $ curl $hostname:4243/images/json ...
I think docker is almost practical for production environment since it cames to run on CentOS.