Usually, in finch you would combine Endpoints first using :+: operator, and only after that convert it to Finagle service, so routing would be handled for you.
If it's crucial to have multiple services, take a look at twitter-server HttpMuxer:
https://github.com/twitter/twitter-server/blob/master/server/src/test/scala/com/twitter/server/util/HttpUtilsTest.scala
Though you would need to handle routing there manually
Endpoint.coproduct method
endpointA coproduct endpointB
I've got a question about error handling in Finch.
For the last couple of years i've been doing it with the good ol' Finagle filter. It allows me to log error, log request and return failed response.
I've tried to use
Endpoint.handle instead, but it means i cant log request in case of error anymore.Is there any other more modern and finch-style way to do it?
https://github.com/finagle/finch/blob/master/examples/src/main/scala/io/finch/middleware/Main.scala
Handling all the errors inside of Kleisli, so roughly the same as finagle filter
F[(T, Either[Throwable, Response])] won't throw on itself, so it's enough to handle the left case of this Either
root which can pull out that request ID, configure the logger and return the logger. I call it withRequestLogger
post("foo" :: withRequestLogger) { logger: Logger =>
@hderms you just hit the most actual topic for me, so I have tons of answers :)
If I understand correctly, you create a logger per request (due to the unique request context) and pass it around. If it's so, then I strongly advise using the famous Reader monad!
You might ask why, and the answer is - because you can pass around logger, context, whatever you feel fancy to pass around without polluting your interfaces API.
The way we solve it in Zalando is to use tagless final + cats-mtl to extract context whenever you need it (actually, that's a topic for a blog post or even a tech talk). Nevertheless, you can fix on specific monad (Reader) and go with it for a while.
Then, to compile Finch endpoints into Finagle service, you're required to have Effect (or ConcurrentEffect) for your monad. Reader doesn't have them out of the box, and the reason is simple: what should be the initial environment?
You have two options here:
mapKoverEndpoint.Compiledand in natural transformation define the initial environment for your reader (say, NoopLogger?). Then in the nextKleisliredefine it based on the request, instantiating the logger you need and usinglocalto propagate this environment down to the next element in the chain.- provide your own implicit
EffectforReader[F[_] : Effect, YourEnv, *]that will run this monad with some initialYourEnv, so finch would pick it up to convertCompiledtoService
Voilà, you don't have these logger endpoints everywhere, with loggers as parameters being passed here and there.
And it's not over yet! Just this night I've published the first version of Odin:
https://github.com/valskalla/odin
It's Fast & Functional logger that is not that features-fancy as log4j yet but has basic options available with something special on top. One of them: context being first-class citizen, so you don't need to mess around with ThreadLocal MDC and/or create loggers per context. It even has a contextual logger that can pick up your context from any ApplicativeAsk (that is Reader) and embed it in the log for you.
It's not that I suggest you to pick it right away and use in production today, we are still to battle test in production this month, as well as some features might be missing. But you might be interested to subscribe to it and follow, and who knows if one day you can start using it in your project :)
*Local things personally. It's even worse than implicits if you think about it. You should believe that someone somewhere put the required data into the magical box of *Local before the moment you're going to use it
local with a new tracing logger.
Hello everyone.
I faced one little problem using finch to build json REST API application.
In my application I have 2 entities User and Pet and they both have CRUD like operations.
Both API groups have their own encoders and decoders (I'm using circe).
class UserResources[F[_]](userRepo: UserRepo[F]) extends Endpoint.Module[F] with UserCodecs {
val create: Endpoint[F, User] = post("user" :: jsonBody[User]) { user: User => userRepo.save(user).map(Ok(_)) }
val get: Endpoint[F, User] = get("user" :: path[Long]) { userId: Long => userRepo.findById(userId).map(Ok(_)) }
...
val endpoints = (create :+: get)
}
class PetResources[F[_]](petRepo: PetRepo[F]) extends Endpoint.Module[F] with PetCodecs {
val create: Endpoint[F, User] = post("pet" :: jsonBody[Pet]) { pet: Pet => petRepo.save(user).map(Ok(_)) }
val get: Endpoint[F, User] = get("pet" :: path[Long]) { userId: Long => petRepo.findById(userId).map(Ok(_)) }
...
val endpoints = (create :+: get)
}Then I use them in this fashion:
val allEndpoints = (new UserResources(repo).endpoints :+: new PetResources(repo2).endpoints)
val api = Bootstrap.serve[Application.Json](allEndpoints).toServiceBut this call require same instances of Encoder/Decoderwhich are defined in *Codecs trait for .toService call to materialise the service. I understand why we should have instances in both situations.
Could you please suggest to me how I can better organise code in similar fashion, but without codecs instances duplicate?
Compiler picks it up from there on its own without any imports.
If you need to describe it for types outside of your application (like library types), you might as well to keep it inside a package object (or just an object) and import those implicits from there