Introduction to Docker Overlay Networking

Overlay networks are at the beating heart of many cloud-native microservices apps. In this chapter, we’ll cover the fundamentals of native Docker overlay networking.

Docker overlay networking on Windows has feature parity with Linux. This means the examples we’ll use in this chapter will all work on Linux and Windows.

Let’s do some networking magic.

The TLDR

In the real world, it’s vital that containers can communicate with each other reliably and securely, even when they’re on different hosts that are on different networks. This is where overlay networking comes into play. It allows you to create a flat, secure, layer-2 network, spanning multiple hosts. Containers connect to this and can communicate directly.

Docker offers native overlay networking that is simple to configure and secure by default.

Behind the scenes, it’s built on top of libnetwork and drivers. libnetwork is the canonical implementation of the Container Network Model (CNM) and drivers are pluggable components that implement different networking technologies and topologies. Docker offers native drivers, including the overlay driver.