http4s - migrate from Blaze to Ember

Author: ivan-klass

build.sbt

@@ -390,7 +390,7 @@ lazy val clientTestServer = (projectMatrix in file("client/testserver"))
     publish / skip := true,
     libraryDependencies ++= Seq(
       "org.http4s" %% "http4s-dsl" % Versions.http4s,
-      "org.http4s" %% "http4s-blaze-server" % Versions.http4sBlazeServer,
+      "org.http4s" %% "http4s-ember-server" % Versions.http4s,
       "org.http4s" %% "http4s-circe" % Versions.http4s,
       logback
     ),
@@ -533,7 +533,7 @@ lazy val perfTests: ProjectMatrix = (projectMatrix in file("perf-tests"))
       "io.github.classgraph" % "classgraph" % "4.8.179",
       "org.http4s" %% "http4s-core" % Versions.http4s,
       "org.http4s" %% "http4s-dsl" % Versions.http4s,
-      "org.http4s" %% "http4s-blaze-server" % Versions.http4sBlazeServer,
+      "org.http4s" %% "http4s-ember-server" % Versions.http4s,
       "org.typelevel" %%% "cats-effect" % Versions.catsEffect,
       logback
     ),
@@ -1143,7 +1143,7 @@ lazy val swaggerUiBundle: ProjectMatrix = (projectMatrix in file("docs/swagger-u
     name := "tapir-swagger-ui-bundle",
     libraryDependencies ++= Seq(
       "com.softwaremill.sttp.apispec" %% "openapi-circe-yaml" % Versions.sttpApispec,
-      "org.http4s" %% "http4s-blaze-server" % Versions.http4sBlazeServer % Test,
+      "org.http4s" %% "http4s-ember-server" % Versions.http4s % Test,
       scalaTest.value % Test
     )
   )
@@ -1169,7 +1169,7 @@ lazy val redocBundle: ProjectMatrix = (projectMatrix in file("docs/redoc-bundle"
     name := "tapir-redoc-bundle",
     libraryDependencies ++= Seq(
       "com.softwaremill.sttp.apispec" %% "openapi-circe-yaml" % Versions.sttpApispec,
-      "org.http4s" %% "http4s-blaze-server" % Versions.http4sBlazeServer % Test,
+      "org.http4s" %% "http4s-ember-server" % Versions.http4s % Test,
       scalaTest.value % Test
     )
   )
@@ -1304,7 +1304,7 @@ lazy val http4sServer: ProjectMatrix = (projectMatrix in file("server/http4s-ser
     scalaVersions = scala2And3Versions,
     settings = commonJvmSettings ++ Seq {
       libraryDependencies ++= Seq(
-        "org.http4s" %%% "http4s-blaze-server" % Versions.http4sBlazeServer % Test
+        "org.http4s" %%% "http4s-ember-server" % Versions.http4s % Test
       )
     }
   )
@@ -1320,7 +1320,7 @@ lazy val http4sServerZio: ProjectMatrix = (projectMatrix in file("server/http4s-
     name := "tapir-http4s-server-zio",
     libraryDependencies ++= Seq(
       "dev.zio" %% "zio-interop-cats" % Versions.zioInteropCats,
-      "org.http4s" %% "http4s-blaze-server" % Versions.http4sBlazeServer % Test
+      "org.http4s" %% "http4s-ember-server" % Versions.http4s % Test
     )
   )
   .jvmPlatform(scalaVersions = scala2And3Versions, settings = commonJvmSettings)
@@ -1888,7 +1888,7 @@ lazy val http4sClient: ProjectMatrix = (projectMatrix in file("client/http4s-cli
     name := "tapir-http4s-client",
     libraryDependencies ++= Seq(
       "org.http4s" %% "http4s-core" % Versions.http4s,
-      "org.http4s" %% "http4s-blaze-client" % Versions.http4sBlazeClient % Test,
+      "org.http4s" %% "http4s-ember-client" % Versions.http4s % Test,
       "com.softwaremill.sttp.shared" %% "fs2" % Versions.sttpShared % Optional
     )
   )
@@ -2050,7 +2050,7 @@ lazy val examples: ProjectMatrix = (projectMatrix in file("examples"))
       "com.github.jwt-scala" %% "jwt-circe" % Versions.jwtScala,
       "org.http4s" %% "http4s-dsl" % Versions.http4s,
       "org.http4s" %% "http4s-circe" % Versions.http4s,
-      "org.http4s" %% "http4s-blaze-server" % Versions.http4sBlazeServer,
+      "org.http4s" %% "http4s-ember-server" % Versions.http4s,
       "org.mock-server" % "mockserver-netty" % Versions.mockServer,
       "io.opentelemetry" % "opentelemetry-sdk" % Versions.openTelemetry,
       "io.opentelemetry" % "opentelemetry-sdk-metrics" % Versions.openTelemetry,
@@ -2118,7 +2118,7 @@ lazy val documentation: ProjectMatrix = (projectMatrix in file("generated-doc"))
     name := "doc",
     libraryDependencies ++= Seq(
       "org.playframework" %% "play-netty-server" % Versions.playServer,
-      "org.http4s" %% "http4s-blaze-server" % Versions.http4sBlazeServer,
+      "org.http4s" %% "http4s-ember-server" % Versions.http4s,
       "com.softwaremill.sttp.apispec" %% "openapi-circe-yaml" % Versions.sttpApispec,
       "com.softwaremill.sttp.apispec" %% "asyncapi-circe-yaml" % Versions.sttpApispec
     ),

client/http4s-client/src/test/scala/sttp/tapir/client/http4s/Http4sClientTests.scala

@@ -1,11 +1,10 @@
 package sttp.tapir.client.http4s
 
 import cats.effect.IO
-import org.http4s.blaze.client.BlazeClientBuilder
+import org.http4s.ember.client.EmberClientBuilder
 import org.http4s.{Request, Response, Uri}
 import sttp.tapir.client.tests.ClientTests
 import sttp.tapir.{DecodeResult, Endpoint}
-import scala.concurrent.ExecutionContext.global
 
 abstract class Http4sClientTests[R] extends ClientTests[R] {
   override def send[A, I, E, O](
@@ -35,7 +34,7 @@ abstract class Http4sClientTests[R] extends ClientTests[R] {
   }
 
   private def sendAndParseResponse[Result](request: Request[IO], parseResponse: Response[IO] => IO[Result]) =
-    BlazeClientBuilder[IO](global).resource.use { client =>
+    EmberClientBuilder.default[IO].build.use { client =>
       client.run(request).use(parseResponse)
     }
 }

client/testserver/src/main/scala/sttp/tapir/client/tests/HttpServer.scala

@@ -3,12 +3,13 @@ package sttp.tapir.client.tests
 import cats.effect._
 import cats.effect.std.Queue
 import cats.effect.unsafe.implicits.global
+import com.comcast.ip4s
 import cats.implicits._
 import fs2.{Pipe, Stream}
 import org.http4s.dsl.io._
 import org.http4s.headers.{Accept, `Content-Type`}
 import org.http4s.server.Router
-import org.http4s.blaze.server.BlazeServerBuilder
+import org.http4s.ember.server.EmberServerBuilder
 import org.http4s.server.middleware._
 import org.http4s.server.websocket.WebSocketBuilder2
 import org.http4s.websocket.WebSocketFrame
@@ -33,7 +34,7 @@ class HttpServer(port: Port) {
 
   private val logger = LoggerFactory.getLogger(getClass)
 
-  private var stopServer: IO[Unit] = _
+  private val stopServer: Deferred[IO, Unit] = Deferred.unsafe[IO, Unit]
 
   //
 
@@ -213,22 +214,19 @@ class HttpServer(port: Port) {
   //
 
   def start(): Unit = {
-    val (_, _stopServer) = BlazeServerBuilder[IO]
-      .withExecutionContext(ExecutionContext.global)
-      .bindHttp(port)
+    EmberServerBuilder
+      .default[IO]
+      .withPort(ip4s.Port.fromInt(port).get)
       .withHttpWebSocketApp(app)
-      .resource
-      .map(_.address.getPort)
-      .allocated
+      .build
+      .use(_ => stopServer.get)
       .unsafeRunSync()
 
-    stopServer = _stopServer
-
     logger.info(s"Server on port $port started")
   }
 
   def close(): Unit = {
-    stopServer.unsafeRunSync()
+    stopServer.complete(()).unsafeRunSync()
     logger.info(s"Server on port $port stopped")
   }
 }

doc/server/http4s.md

@@ -52,11 +52,11 @@ The capability can be added to the classpath independently of the interpreter th
 ## Http4s backends
 
 Http4s integrates with a couple of [server backends](https://http4s.org/v1.0/integrations/), the most popular being 
-Blaze and Ember. In the [examples](../examples.md) and throughout the docs we use Blaze, but other backends can be used
+Blaze and Ember. In the [examples](../examples.md) and throughout the docs we use Ember, but other backends can be used
 as well. This means adding another dependency, such as:
 
 ```scala
-"org.http4s" %% "http4s-blaze-server" % Http4sVersion
+"org.http4s" %% "http4s-ember-server" % Http4sVersion
 ```
 
 ## Web sockets
@@ -75,24 +75,21 @@ import sttp.tapir.*
 import sttp.tapir.server.http4s.Http4sServerInterpreter
 import cats.effect.IO
 import org.http4s.HttpRoutes
-import org.http4s.blaze.server.BlazeServerBuilder
+import org.http4s.ember.server.EmberServerBuilder
 import org.http4s.server.Router
 import org.http4s.server.websocket.WebSocketBuilder2
 import fs2.*
 import scala.concurrent.ExecutionContext
 
-given ExecutionContext = scala.concurrent.ExecutionContext.Implicits.global
-
 val wsEndpoint: PublicEndpoint[Unit, Unit, Pipe[IO, String, String], Fs2Streams[IO] with WebSockets] =
   endpoint.get.in("count").out(webSocketBody[String, CodecFormat.TextPlain, String, CodecFormat.TextPlain](Fs2Streams[IO]))
 
 val wsRoutes: WebSocketBuilder2[IO] => HttpRoutes[IO] =
   Http4sServerInterpreter[IO]().toWebSocketRoutes(wsEndpoint.serverLogicSuccess[IO](_ => ???))
-    
-BlazeServerBuilder[IO]
-  .withExecutionContext(summon[ExecutionContext])
-  .bindHttp(8080, "localhost")
-  .withHttpWebSocketApp(wsb => Router("/" -> wsRoutes(wsb)).orNotFound)        
+
+EmberServerBuilder
+  .default[IO]
+  .withHttpWebSocketApp(wsb => Router("/" -> wsRoutes(wsb)).orNotFound)
 ```
 
 ## Server Sent Events

doc/server/zio-http4s.md

@@ -99,11 +99,11 @@ The capability can be added to the classpath independently of the interpreter th
 ## Http4s backends
 
 Http4s integrates with a couple of [server backends](https://http4s.org/v1.0/integrations/), the most popular being
-Blaze and Ember. In the [examples](../examples.md) and throughout the docs we use Blaze, but other backends can be used
+Blaze and Ember. In the [examples](../examples.md) and throughout the docs we use Ember, but other backends can be used
 as well. This means adding another dependency, such as:
 
 ```scala
-"org.http4s" %% "http4s-blaze-server" % Http4sVersion
+"org.http4s" %% "http4s-ember-server" % Http4sVersion
 ```
 
 ## Web sockets
@@ -121,7 +121,7 @@ import sttp.tapir.{CodecFormat, PublicEndpoint}
 import sttp.tapir.ztapir.*
 import sttp.tapir.server.http4s.ztapir.ZHttp4sServerInterpreter
 import org.http4s.HttpRoutes
-import org.http4s.blaze.server.BlazeServerBuilder
+import org.http4s.ember.server.EmberServerBuilder
 import org.http4s.server.Router
 import org.http4s.server.websocket.WebSocketBuilder2
 import scala.concurrent.ExecutionContext
@@ -131,8 +131,6 @@ import zio.stream.Stream
 
 def runtime: Runtime[Any] = ??? // provided by ZIOAppDefault
 
-given ExecutionContext = scala.concurrent.ExecutionContext.Implicits.global
-
 val wsEndpoint: PublicEndpoint[Unit, Unit, Stream[Throwable, String] => Stream[Throwable, String], ZioStreams with WebSockets] =
   endpoint.get.in("count").out(webSocketBody[String, CodecFormat.TextPlain, String, CodecFormat.TextPlain](ZioStreams))
 
@@ -141,13 +139,11 @@ val wsRoutes: WebSocketBuilder2[Task] => HttpRoutes[Task] =
 
 val serve: Task[Unit] =
   ZIO.executor.flatMap(executor =>
-    BlazeServerBuilder[Task]
-      .withExecutionContext(executor.asExecutionContext)
-      .bindHttp(8080, "localhost")
+    EmberServerBuilder
+      .default[Task]
       .withHttpWebSocketApp(wsb => Router("/" -> wsRoutes(wsb)).orNotFound)
-      .serve
-      .compile
-      .drain
+      .build
+      .useForever
   )  
 ```
 

doc/tutorials/07_cats_effect.md

@@ -132,11 +132,11 @@ standard code to start a server and handle requests until the application is int
 ```scala
 //> using dep com.softwaremill.sttp.tapir::tapir-core:@VERSION@
 //> using dep com.softwaremill.sttp.tapir::tapir-http4s-server:@VERSION@
-//> using dep org.http4s::http4s-blaze-server:0.23.16
+//> using dep org.http4s::http4s-ember-server:0.23.29
 
 import cats.effect.{ExitCode, IO, IOApp}
 import org.http4s.HttpRoutes
-import org.http4s.blaze.server.BlazeServerBuilder
+import org.http4s.ember.server.EmberServerBuilder
 import org.http4s.server.Router
 import sttp.tapir.*
 import sttp.tapir.server.http4s.Http4sServerInterpreter
@@ -154,12 +154,11 @@ object HelloWorldTapir extends IOApp:
     .toRoutes(helloWorldEndpoint)
 
   override def run(args: List[String]): IO[ExitCode] =
-    BlazeServerBuilder[IO]
-      .bindHttp(8080, "localhost")
+    EmberServerBuilder
+      .default[IO]
       .withHttpApp(Router("/" -> helloWorldRoutes).orNotFound)
-      .resource
-      .use(_ => IO.never)
-      .as(ExitCode.Success)
+      .build
+      .useForever
 ```
 
 First of all, you might notice that instead of the `@main` method, we are extending the `IOApp` trait. This is needed,
@@ -169,8 +168,8 @@ the `IOApp` will handle evaluating the `IO` description and actually running the
 
 Secondly, with http4s we need to use a specific server implementation (http4s itself is only an API to define endpoints - 
 kind of a middle-man between Tapir and low-level networking code). We can choose from `blaze` and `ember` servers, here 
-we're using the `blaze` one, which is reflected in the additional dependency and the server configuration constructor: 
-`BlazeServerBuilder`.
+we're using the `ember` one, which is reflected in the additional dependency and the server configuration constructor: 
+`EmberServerBuilder`.
 
 Finally, we've got the `run` method implementation, which attaches our interpreted route to the root context `/` and
 exposes the server on `localhost:8080`.
@@ -195,12 +194,12 @@ the second step that we need to perform:
 //> using dep com.softwaremill.sttp.tapir::tapir-core:@VERSION@
 //> using dep com.softwaremill.sttp.tapir::tapir-http4s-server:@VERSION@
 //> using dep com.softwaremill.sttp.tapir::tapir-swagger-ui-bundle:@VERSION@
-//> using dep org.http4s::http4s-blaze-server:0.23.16
+//> using dep org.http4s::http4s-ember-server:0.23.29
 
 import cats.effect.{ExitCode, IO, IOApp}
 import cats.syntax.all.*
 import org.http4s.HttpRoutes
-import org.http4s.blaze.server.BlazeServerBuilder
+import org.http4s.ember.server.EmberServerBuilder
 import org.http4s.server.Router
 import sttp.tapir.*
 import sttp.tapir.server.http4s.Http4sServerInterpreter
@@ -226,17 +225,16 @@ object HelloWorldTapir extends IOApp:
   val allRoutes: HttpRoutes[IO] = helloWorldRoutes <+> swaggerRoutes
 
   override def run(args: List[String]): IO[ExitCode] =
-    BlazeServerBuilder[IO]
-      .bindHttp(8080, "localhost")
+    EmberServerBuilder
+      .default[IO]
       .withHttpApp(Router("/" -> allRoutes).orNotFound)
-      .resource
-      .use(_ => IO.never)
-      .as(ExitCode.Success)
+      .build
+      .useForever
 ```
 
 Hence, we first generate endpoint descriptions, which correspond to exposing the Swagger UI (containing the generated
 OpenAPI yaml for our `/hello/world` endpoint), which use `IO` to express their server logic. Then, we interpret those
-endpoints as `HttpRoutes[IO]`, which we can expose using http4's blaze server.
+endpoints as `HttpRoutes[IO]`, which we can expose using http4's ember server.
 
 ## Other concepts covered so far
 

docs/redoc-bundle/src/test/scala/sttp/tapir/redoc/bundle/RedocInterpreterTest.scala

@@ -2,8 +2,9 @@ package sttp.tapir.redoc.bundle
 
 import cats.effect.IO
 import cats.effect.unsafe.implicits.global
+import com.comcast.ip4s.Port
 import org.http4s.HttpRoutes
-import org.http4s.blaze.server.BlazeServerBuilder
+import org.http4s.ember.server.EmberServerBuilder
 import org.http4s.server.Router
 import org.scalatest.Assertion
 import org.scalatest.funsuite.AsyncFunSuite
@@ -66,10 +67,11 @@ class RedocInterpreterTest extends AsyncFunSuite with Matchers {
           .fromEndpoints[IO](List(testEndpoint), "The tapir library", "1.0.0")
       )
 
-    BlazeServerBuilder[IO]
-      .bindHttp(0, "localhost")
+    EmberServerBuilder
+      .default[IO]
+      .withPort(Port.fromInt(0).get)
       .withHttpApp(Router(s"/${context.mkString("/")}" -> redocUIRoutes).orNotFound)
-      .resource
+      .build
       .use { server =>
         IO {
           val port = server.address.getPort

docs/swagger-ui-bundle/src/test/scala/sttp/tapir/swagger/bundle/SwaggerInterpreterTest.scala

@@ -2,8 +2,9 @@ package sttp.tapir.swagger.bundle
 
 import cats.effect.IO
 import cats.effect.unsafe.implicits.global
+import com.comcast.ip4s.Port
 import org.http4s.HttpRoutes
-import org.http4s.blaze.server.BlazeServerBuilder
+import org.http4s.ember.server.EmberServerBuilder
 import org.http4s.server.Router
 import org.scalatest.Assertion
 import org.scalatest.funsuite.AsyncFunSuite
@@ -33,10 +34,11 @@ class SwaggerInterpreterTest extends AsyncFunSuite with Matchers {
           .fromEndpoints[IO](List(testEndpoint), "The tapir library", "1.0.0")
       )
 
-    BlazeServerBuilder[IO]
-      .bindHttp(0, "localhost")
+    EmberServerBuilder
+      .default[IO]
+      .withPort(Port.fromInt(0).get)
       .withHttpApp(Router(s"/${context.mkString("/")}" -> swaggerUIRoutes).orNotFound)
-      .resource
+      .build
       .use { server =>
         IO {
           val port = server.address.getPort