Multiple network issues

Hi there,

Last Friday I decided to rebuild one of my servers and in the meantime learning something about Docker. I installed coreOS and I’m using the docker version: 1.12.6 . While I’m getting the hang of this I’m running into an issue with multiple networks, when I have a service with 2 (haven’t tried more yet) one of the 2 does not seem to work. I can’t figure out if this is a bug or I’m doing something wrong.
I have started using docker-compose and boiled it down to this:

Now when I run bash from the web service I’m able to ping the proxy service but not the app service. It does resolve to an IP address but there is no answer. See the following link for the proof and some inspect details if needed:

Anyone knows what I’m doing wrong or how I should do this?