sphuff/docker-localhost-networking

How do I run this?

Assuming you have docker and docker-compose set up, run docker-compose up -d.

What's happening?

A docker image should be treated as a completely separate machine, so a call to localhost:5000 on your machine is not the same as a call to localhost:5000 in your container.

Your two options to contact other services over localhost are:

1. Don't do that, and use the service's alias instead. For example, a call to localhost:5000 becomes server:5000 when you service is named server. This works because docker-compose creates a default network over which your containers can communicate.
2. Specify the network_mode as host for the client container. A host network mode will make sure that your container is using the same networking stack as your host machine. In other words, localhost:5000 on your laptop becomes localhost:5000 in the client container. This is not recommended, because it means that your ports are exposed on the host machine and could network with unintended services.