In this chapter, we added three different implementations of profile pictures to our chat application. First we asked the authentication service to provide a URL for us to use. We did this by using Gomniauth's abstraction of the user resource data, which we then included as part of the user interface every time a user would send a message. Using Go's zero (or default) initialization pattern, we were able to refer to different implementations of our Avatar interface without actually creating any instances.

We stored data in a cookie for when the user would log in. Therefore, and also given the fact that cookies persist between builds of our code, we added a handy logout feature to help us validate our changes, which we also exposed to our users so that they could log out too. Other small changes to the code and the inclusion of Bootstrap on our chat page dramatically improved the look and feel of our application.

We used MD5 hashing in Go to implement the Gravatar.com API by hashing...