just started to use them for an elixir/phoenix project. multi region with distributed nodes just works. feels almost magically after all the aws work I've done the past few years.
I still wouldn't say we do any magic Elixir stuff; rather, our platform just happens to have a combination of features (particularly edge delivery for stuff like LiveView and zero-config private networking for clustering) that make Elixir apps sing.
But we've got full-time people working on Elixir now, too; we'll see where that goes. We've still got Elixir limerence here. :)
They're not doing anything special to make Elixir specifically better yet, but their private networking is already amazing for it - you can cluster across arbitrary regions completely trivially. It's a really good fit for Elixir clustering as-is even without anything specially built for it. I have no idea how you'd do multi-region clustering in AWS but I'm certain it'd be a lot harder.
I was under the impression that fly.io today (though they are working on it) doesn’t do anything unique to make hosting elixir/Phoenix app easier.
See this comment by the fly.io team.
https://news.ycombinator.com/item?id=27704852