(This answer is based on the chat we had in the comments)
In order to expose the web server from inside the container to the host it needs to bind to 0.0.0.0 and not to 127.0.0.1. Using 0.0.0.0 ensures that the web server binds to the bridge interface that can be accessed from the host side.
Relevant Docker docs: https://docs.docker.com/v17.09/engine/userguide/networking/default_network/binding/