I\'m running a webpack-dev-server application inside a Docker container (node:4.2.1). If I try to connect to the server port from within the container - it works fine. Howev
you docker container has mapped the EXPOSE'd port to a host port
docker run -p x:y
your VM (if you are using docker machine with a VM) has forwarded that mapped port to the actual host (the host of the VM).
See "How to access tomcat running in docker container from browser?"