The introduction of user-defined networks signaled a big change in Docker networking. While the ability to provision custom networks was the big news, there were also major enhancements in name resolution. User-defined networks can benefit from what’s being named embedded DNS. The Docker engine itself now has the ability to provide name resolution to all of the containers. This is a marked improvement from the legacy solution where the only means for name resolution was external DNS or linking, which relied on the hosts file. In this recipe, we’ll walk through how to use and configure embedded DNS.
In this recipe, we’ll be demonstrating the configuration on a single Docker host. It is assumed that this host has Docker installed and that Docker is in its default configuration. We’ll be altering name resolution settings on the host, so you’ll need root-level access.