Allow prepending input path to HttpInterpreter generated Tapir endpoints

[olisikh]

Hi,

I did not manage to implement full endpoints mapping because mapping over endpoints would depend on Streams and I can't figure out the type parameters 😞, since streams instance is provided only when .serverEndpoints is called (last step in the builder).

But I managed to expose Tapir's .prependIn endpoint combinator to add an extra EndpointInput[Unit] for the PublicEndpoint that HttpInterpreter makes.

It does the job, I can use HttpInterpreter like this now (tested with real project):

val status = ...
val api = ...
val graphql = HttpInterpreter(gqlInterpreter)
  .prependInput("graphql" / "api")
  .intercept[Any](myInterceptor)
  .serverEndpoints[Env, ZioStreams](ZioStreams)
  
 NettyZioSever[Env]()
   .addEndpoints(status)
   .addEndpoints(api)
   .addEndpoints(swagger)
   ...
   .start()

Any help / feedback is very welcome 🙏

Issue #2185

Oleksii

[ghostdogpr]

I gave it a try and I see what you mean about the streams type. This solution is a little bit specific but the implementation is short and simple so it seems ok. @kyri-petrou @paulpdaniels any better idea or shall we just ship this?

[paulpdaniels]

Is there anything we can do with this other than append path prefixes? Perhaps it would be better in that case to just expose a prependPath(path: String) then?

[olisikh]

Hi @paulpdaniels,

I think it has to be EndpointInput[Unit].

The path with multiple segments and without output into serverLogic is encoded as EndpointInput[Unit] in Tapir, if we were to make it a String, it would make 1-segment paths and that is not very useful.

To my knowledge this is how it works:

.in("hello")             // makes it a /hello
.in("hello" / "world")   // makes it a /hello/world
.in("hello/world")       // makes it a hello%2Fworld (Tapir would encode slashes within a String)

PS I can think of making the input as def prependPath(pathPrefix: List[String]) instead and then combine the list elements with / to make it EndpointInput[Unit]

Example:

HttpInterpreter(graphql)
  .prependPath("graphql" :: "api" :: Nil)
  ...
  .serverEndpoints[Env, ZioStreams](ZioStreams)

[olisikh]

Narrowed it down to just .prependPath(path: List[String]), and I also like it more. Please let me know if it looks good for you and feel free to change anything the way you like 🙏

PS I tried to make input as EndpointInput.FixedPath[Unit] but at the call-site compiler can't infer that "hello" / "world" is a FixedPath[Unit] 🤷‍♂️

[ghostdogpr]

How about the WebSocketInterpreter? Can it be added there too?

[ghostdogpr]

Thanks!