Book Image

Docker Networking Cookbook

Book Image

Docker Networking Cookbook

Overview of this book

Networking functionality in Docker has changed considerably since its first release, evolving to offer a rich set of built-in networking features, as well as an extensible plugin model allowing for a wide variety of networking functionality. This book explores Docker networking capabilities from end to end. Begin by examining the building blocks used by Docker to implement fundamental containing networking before learning how to consume built-in networking constructs as well as custom networks you create on your own. Next, explore common third-party networking plugins, including detailed information on how these plugins inter-operate with the Docker engine. Consider available options for securing container networks, as well as a process for troubleshooting container connectivity. Finally, examine advanced Docker networking functions and their relevant use cases, tying together everything you need to succeed with your own projects.
Table of Contents (18 chapters)
Docker Networking Cookbook
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Verifying name resolution


DNS resolution for containers has always been rather straightforward. The container received the same DNS configuration as the host. However, with the advent of user-defined networks and the embedded DNS server, this has now become a little trickier. A common problem in many of the DNS issues I've seen is not understanding how the embedded DNS server works and how to validate that it's working correctly. In this recipe, we'll step through a container DNS configuration to validate which DNS server it is using to resolve specific namespaces.

Getting ready

In this recipe, we'll be using a single Docker host. It is assumed that Docker is installed and in its default configuration. You'll also need root-level access in order to inspect and change the host's networking and firewall configuration.

How to do it…

The standard DNS configuration for Docker without user-defined networks is to simply copy the DNS configuration from the host into the container. In these cases, the...