Docker bridge network Configuration for containers
Since you are using the tag "Docker-Machine" I'm assuming that you are using Docker Toolbox to manage Docker.  The problem is most likely an issue with Virtual Box configuration than your Docker configuration.

When you try pinging your container on port 9001, use the ip 0.0.0.0 instead of 127.0.0.1 or localhost.  Another way to test would be to get the IP address of the docker-machine, docker-machine ip, and use this IP to ping your container (e.g. use 192.168.99.100:9001.

If you are trying to access the container from another computer you may have to look into a solution like port forwarding as described here.