This is an example about dockerizing a socket.io service for a generic application.
$ git clone https://github.com/feload/dashboard-socket.git
$ cd dashboard-socket
$ docker build -t dashboard .
$ docker run -d -p 8181:8181 dashboard-socket
$ docker logs dashboard -f
$ http-server
Reference: http-server
"user connected" will prompt in the logs from dashboard container.