Btw, Cowboy also supports gzipping. You only need to pass compress: true to the server configuration (on Phoenix this means under the :http/:https keys in your configuration):
config :my_app, MyApp.Endpoint,
http: [compress: true, ...],
https: [compress: true, ...]
The Plug can still be handy in many situations, for example, if you cannot compress all routes, the Plug gives you flexibility where the Cowboy configuration cannot.
