An API to rule them all - to define or customize new API at runtime / published by https://github.com/dacr/code-examples-manager #dbccfc26-c532-4aa9-b3cd-eb13cbaa5370/764dc89bc8faf304aa6e1a5394904ae8cca6d0e4

tapir-zio-dynamic-api.sc

// summary : An API to rule them all - to define or customize new API at runtime
// keywords : scala, zio, tapir, http, zhttp, stateful, state, @testable, @exclusive
// publish : gist
// authors : David Crosson
// license : Apache NON-AI License Version 2.0 (https://raw.githubusercontent.com/non-ai-licenses/non-ai-licenses/main/NON-AI-APACHE2)
// id : dbccfc26-c532-4aa9-b3cd-eb13cbaa5370
// created-on : 2023-12-08T18:45:32+01:00
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : scala-cli $file
// test-with : curl -L http://127.0.0.1:8080/hello/david

// ---------------------
//> using scala "3.3.1"
//> using dep "com.softwaremill.sttp.tapir::tapir-zio:1.9.4"
//> using dep "com.softwaremill.sttp.tapir::tapir-zio-http-server:1.9.4"
//> using lib "com.softwaremill.sttp.tapir::tapir-swagger-ui-bundle:1.9.4"
// ---------------------

import sttp.tapir.ztapir.*
import sttp.tapir.EndpointIO.Example
import sttp.tapir.server.ziohttp.ZioHttpInterpreter
import sttp.apispec.openapi.Info
import sttp.tapir.swagger.bundle.SwaggerInterpreter
import zio.*, zio.http.Server

/*
curl -L http://127.0.0.1:8080/docs
curl http://127.0.0.1:8080/hello/david
curl http://127.0.0.1:8080/hello/joe
 */

object WebApp extends ZIOAppDefault {

  case class AppState(
    serversFibers: Map[Int, Fiber[Throwable, Nothing]] = Map.empty
  ) {
    def manage(serverId: Int, serverFiber: Fiber[Throwable, Nothing]): AppState =
      copy(serversFibers = serversFibers + (serverId -> serverFiber))
  }

  type WebAppEnv = Ref[AppState]

  // --------------------------------------------------

  val greetingExamples = List(Example.of("Hello"), Example.of("Hi"), Example.of("Good morning"))

  val startEndPoint =
    endpoint
      .description("Start a new customized API")
      .get
      .in("start")
      .in(path[String]("greeting").examples(greetingExamples))
      .in(path[Int]("port").example(8081))
      .out(emptyOutput)

  val startRoute = startEndPoint.zServerLogic[WebAppEnv]((greeting, port) => buildDynamicServer(greeting, port).logError.ignore)

  val apiRoutes = List(startRoute)

  val docRoutes =
    SwaggerInterpreter()
      .fromServerEndpoints(
        apiRoutes,
        Info(title = "An API to define and control new API", version = "1.0")
      )

  // --------------------------------------------------
  def buildDynamicServer(greetingToUse: String, port: Int) = {
    val dynamicEndPoint =
      endpoint
        .description(s"Dynamically defined $greetingToUse")
        .get
        .in(s"greeting")
        .in(path[String]("name").example("joe"))
        .out(stringBody)

    val dynamicRoute = dynamicEndPoint.zServerLogic[WebAppEnv](_ => ZIO.succeed(greetingToUse))

    val dynamicDocRoutes =
      SwaggerInterpreter()
        .fromServerEndpoints(
          List(dynamicRoute),
          Info(title = "Dynamic generated API", version = "1.0")
        )
    val dynamicRoutes    = ZioHttpInterpreter().toHttp(List(dynamicRoute) ++ dynamicDocRoutes)
    for {
      _           <- ZIO.logInfo(s"NEW API available http://127.0.0.1:$port/docs")
      serverFiber <- Server
                       .serve(dynamicRoutes)
                       .provideSomeLayer(Server.defaultWithPort(port))
                       .forkDaemon
      ref         <- ZIO.service[Ref[AppState]]
      state       <- ref.updateAndGet(state => state.manage(port, serverFiber))
    } yield ()
  }
  // --------------------------------------------------

  val routes = ZioHttpInterpreter().toHttp(apiRoutes ++ docRoutes)

  // --------------------------------------------------
  val appStateLayer = ZLayer(Ref.make(AppState()))

  val defaultPort  = 8080
  override def run =
    ZIO.logInfo(s"META API available http://127.0.0.1:$defaultPort/docs") *>
      Server
        .serve(routes)
        .provide(appStateLayer, Server.default)

}

WebApp.main(Array.empty)