isomarcte / http4s-bracket

Bracket, and related utilities, For Http4s

Http4s Bracket

This project provides a function for bracketing the processing of a Request and the full completion of a Response from http4s, similar to cats.effect.Bracket from cats-effect.

You might wonder why we can't just use cats.effect.Bracket. To answer that question, let's consider the HttpRoutes type from http4s.

  type HttpRoutes[F[_]] = Kleisli[OptionT[F, *], Request[F], Response[F]]

You can already bracket on this type, assuming your F type has an instance of cats.effect.Bracket (which it typically will). However, this will only bracket over the generation of the Response[F] type, not the complete processing of the Response.body fs2.Stream[Byte].

It is this feature which BracketRequestResponseMiddleware provides.

This function is very useful for metrics gathering, logging, and controlling concurrency in a http4s system.

Indeed versions of similar functions exist in http4s right now, but they are all specialized to a particular usage, not generalized.

It is my intent to PR this function into http4s proper. If and when it is merged and released, this repo will be closed.