Forwarding api with saturn returns 404

[Freymaurer]

This is a continuation of issue #197. After the DateTime issue was fixed i updated from Fable.Remoting.Giraffe 4.10 to 4.13 and noticed how all apis managed by Fable.Remoting returned with 404. I looked into the issue you linked by @Arshia001 and did some testing.

As background information, i am using the SAFE stack with saturn and this problem occurs during development (with webpack).

let testWebApp =
    Remoting.createApi()
    |> Remoting.withRouteBuilder Route.builder
    |> Remoting.fromValue testApi
    |> Remoting.withDiagnosticsLogger(printfn "%A")
    |> Remoting.withErrorHandler(
        (fun x y -> Propagate (sprintf "[SERVER SIDE ERROR]: %A @ %A" x y))
    )
    |> Remoting.buildHttpHandler

let testRouter = 
    /// does not work
    forward "/api/ITestAPI" (fun next ctx ->
        testWebApp next ctx
    ) 
   /// does work
   forward "" (fun next ctx ->
        testWebApp next ctx
   )

let app = application {
    url "http://localhost:5000/"
    use_router testRouter
    memory_cache
    use_static "public"
    use_gzip
    logging (fun (builder: ILoggingBuilder) -> builder.SetMinimumLevel(LogLevel.Warning) |> ignore)
}

Of course both variants are not active at the same time, i only wrote it like this for easier comparison. As you can see if i don't specify the api url path for forwarding it works.

For the sake of completeness, my apis were written and worked as follows before the update:

let mainApiController = router {
    forward "/ITestAPI" (fun next ctx ->
        testWebApp next ctx
    )
}
let topLevelRouter = router {
    forward "/api" mainApiController

let app = application {
    url "http://localhost:5000/"
    //force_ssl
    use_router topLevelRouter
    memory_cache
    use_static "public"
    use_gzip
    logging (fun (builder: ILoggingBuilder) -> builder.SetMinimumLevel(LogLevel.Warning) |> ignore)
}

I hope this helps to find the problem. IIf you need any more information i will be happy to help. Thanks for all the hard work!

[Zaid-Ajaj]

Thanks a lot for the issue report @Freymaurer, this is very helpful 😄 I will investigate

[kaashyapan]

I think I ran into this issue when trying to add a plug to the pipeline and having 2 remoting api interfaces.
Is there any advice on how to workaround ?

This works

        choose [ 
            route "/api/health" >=> healthHandler
            application2Handler 
            application1Handler 
        ]

This doesnt

        router {
            pipe_through apiKeyPipe
            get "/api/health" healthHandler
            forward "/api/app1" (fun next ctx -> application1Handler next ctx)
            forward "/api" (fun next ctx -> application2Handler next ctx)
        }