Docker Cookbook

Chapter 3. Docker Networking

3.0 Introduction

As you build your distributed application, services that compose it will need to be able to communicate with each other. These services, running in containers, might be on a single host or on multiple hosts and even across data centers. Therefore container networking is a critical enabler of any Docker-based distributed application.

The techniques used for networking containers are very similar to the techniques used to network virtual machines. Containers on a host can be attached to a software switch, and iptables are used to control network traffic between containers and expose processes running in the container on ports of the host.

At installation time, the Docker engine sets up multiple default networking behaviors on your hosts, which gives you a fully working setup from the start. In Recipe 3.1 we start by introducing some Docker commands that let you find the IP addresses of your containers, then we show you how to expose a container port on a host port in Recipe 3.2. In Recipe 3.3 we take a deeper a look at container linking, a mechanism to help with service discovery of multiple containers.

Networking is such an important topic for distributed applications that we felt it necessary to dive deeper into the nuts and bolts of it. Recipe 3.4 explains the default Docker bridge setup while Recipe 3.6 shows you how to change the defaults by modifying the Docker engine options. Recipe 3.8 and Recipe 3.9 go even deeper and show ...