whenever I visit container-ip:8000 or http://localhost:8000, it doesn't work
See [docker/issues/4007][1]: you would need to use port forwarding when using boot2docker on OSX.
That means the VM boot2docker needs to forward the port 8000 to the OSX actual host.
I [mentioned it here][2]:
$ VBoxManage modifyvm "boot2docker-vm" --natpf1 "tcp-port8000,tcp,,8000,,8000";
If the vm is already running, you should run this other command: