Would it be fair to describe plug as a specification that functions to describe code that behaves like middleware in node/express?

In my testing, I needed to put {:plug_cowboy, "~> 1.0"} in mix.exs too. And maybe is needed to explain that the plug LearningPlug is in the file lib/learning_plug.ex . Thanks for your post is greeat!

Yes thanks - perfect for getting your head around it. I am going through the phoenix boilerplate code and trying to figure out where a Plug is defined when they use this format:

plug :protect_from_forgery

Is that a built in plug module? Or something defined in phoenix?

Well explained. Thanks!

Which drawing tool you used in your article?

Well written, with a minimum of fuss. Suggestion; add a reminder to readers to add the my_pipeline app to mix.exs file before trying to start it up.