It’s so interesting how on the one hand people ask for more and more structure guidance within phoenix and then on the other hand it’s held against it.

There’s two parts to the structure discussion. There’s your business logic, where phoenix really doesn’t care what you do. And there’s the my_app_web layer, where again phoenix doesn’t care, but I’d argue conventions are useful for the next person and having worked on other phoenix projects might give you a leg up. Ultimately you can setup your files in whatever structure you want still.

Even though a JSON api won’t necessarily use all the features of phoenix I still think there are a few very useful ones, which would be missing in a bare bandit/plug setup, like the code reloader, features of the router/endpoint and their testing helpers, all the url handling/generation stuff phoenix provides, the error page, …

There is this one too

https://github.com/wojtekmach/mix_install_examples/blob/main/phoenix.exs

is Phoenix overkill?

I believe that question is a result of carrying misconceptions from other languages or frameworks which oftentimes add code bloat and performance penalty. Phoenix is not like that. E.g. in Ruby world, you often see discussion about choosing Rails (heavyweight but complete) vs Sinatra (lightweight, requiring more from the user, but not carrying over bloat).

This dichotomy does not exist in Phoenix. The next sentence is a little stretch, but it should give a nice intuition. In the sense of lightness Plug might be comparable to Sinatra. Now, imagine if Rails was just a generator for a full blown app that glues some Sinatra configs together. Then you could use the quick start convention and remove all the unnecessary stuff.

That is exactly how Phoenix works. It is a layer on top of Plug with conventions and configurations. Even better, you don’t need to start with full Phoenix and remove stuff, the mix phx.new task allows specifying –-no-assets –-no-html –-no-live and you are ready to go.

So, in the end, use Phoenix. It is not like Rails which would pull a lot of unnecessary things. Phoenix can be as lean as you need it while benefitting from easy to follow conventions. It is even fine to use Phoenix to server static content with -–no-ecto.