It's one single application. Most of the secondary services are powered by go/ruby, running independently in non-monolithic way.

Ex-Hubber

One thing I just cannot wrap my head around is Ruby/Rails metaprogramming and attribution of things (as in "where this method/class/macro comes from?"), especially with so many authors trying to do something to the pre-existing stuff, including the standard library bits.

Like, a lot of times I see some baz.foobarify() I have really hard time understanding where the heck that comes from. RubyMine makes wonders and control-clicking gets me there about half of time, but the rest of it it's either "search in all files, hoping that `def foobarify` is unique enough" or "this is crazy, but I'm gonna set a breakpoint, run it and see where this rabbit hole goes".

It feels kinda like Scala (or, to lesser degree, Haskell) magic operators problem, but worse.

I consider myself proficient with a decent number of languages and frameworks, but Ruby/Rails is one arcane mystery that just never clicked. So I really wonder what's the trick to make metaprogramming shenanigans manageable at this scale?

They call it a monolith and the way they describe it I think they are using that term for the application rather than the repo.

They keep saying "monolith".