Simple-Messenger uses flask-socketio to establish communication between clients.
It contains a Makefile which lets start the server as below.
make run
Once started, to get the IP address of the server do the following.
If you use docker-machine,
SIMPLE_SERVER=$(echo $DOCKER_HOST | cut -d '/' -f3 | cut -d ':' -f1)
else if you use docker-for-mac
SIMPLE_SERVER=$(ifconfig en0 | grep 'inet' | cut -d " " -f2)
head over to ${SIMPLE_SERVER}:5000