Allow setting Server header in Netty config (#3615)

build.sbt

@@ -1433,6 +1433,7 @@ lazy val jdkhttpServer: ProjectMatrix = (projectMatrix in file("server/jdkhttp-s
 
 lazy val nettyServer: ProjectMatrix = (projectMatrix in file("server/netty-server"))
   .settings(commonJvmSettings)
+  .enablePlugins(BuildInfoPlugin)
   .settings(
     name := "tapir-netty-server",
     libraryDependencies ++= Seq(

server/netty-server/cats/src/main/scala/sttp/tapir/server/netty/cats/NettyCatsServer.scala

@@ -74,7 +74,7 @@ case class NettyCatsServer[F[_]: Async](routes: Vector[Route[F]], options: Netty
     val channelFuture =
       NettyBootstrap(
         config,
-        new NettyServerHandler(route, unsafeRunAsync, channelGroup, isShuttingDown),
+        new NettyServerHandler(route, unsafeRunAsync, channelGroup, isShuttingDown, config.serverHeader),
         eventLoopGroup,
         socketOverride
       )

server/netty-server/loom/src/main/scala/sttp/tapir/server/netty/loom/NettyIdServer.scala

@@ -97,7 +97,8 @@ case class NettyIdServer(routes: Vector[IdRoute], options: NettyIdServerOptions,
         route,
         unsafeRunF,
         channelGroup,
-        isShuttingDown
+        isShuttingDown,
+        config.serverHeader
       ),
       eventLoopGroup,
       socketOverride

server/netty-server/src/main/scala/sttp/tapir/server/netty/NettyConfig.scala

@@ -43,6 +43,9 @@ import scala.concurrent.duration._
   * @param gracefulShutdownTimeout
   *   If set, attempts to wait for a given time for all in-flight requests to complete, before proceeding with shutting down the server. If
   *   `None`, closes the channels and terminates the server without waiting.
+  *
+  * @param serverHeader
+  *   If set, send this value in the 'Server' response header. If None, don't set the header.
   */
 case class NettyConfig(
     host: String,
@@ -59,7 +62,8 @@ case class NettyConfig(
     eventLoopConfig: EventLoopConfig,
     socketConfig: NettySocketConfig,
     initPipeline: NettyConfig => (ChannelPipeline, ChannelHandler) => Unit,
-    gracefulShutdownTimeout: Option[FiniteDuration]
+    gracefulShutdownTimeout: Option[FiniteDuration],
+    serverHeader: Option[String]
 ) {
   def host(h: String): NettyConfig = copy(host = h)
 
@@ -96,6 +100,8 @@ case class NettyConfig(
 
   def withGracefulShutdownTimeout(t: FiniteDuration) = copy(gracefulShutdownTimeout = Some(t))
   def noGracefulShutdown = copy(gracefulShutdownTimeout = None)
+
+  def serverHeader(h: String): NettyConfig = copy(serverHeader = Some(h))
 }
 
 object NettyConfig {
@@ -114,7 +120,8 @@ object NettyConfig {
     sslContext = None,
     eventLoopConfig = EventLoopConfig.auto,
     socketConfig = NettySocketConfig.default,
-    initPipeline = cfg => defaultInitPipeline(cfg)(_, _)
+    initPipeline = cfg => defaultInitPipeline(cfg)(_, _),
+    serverHeader = Some(s"tapir/${buildinfo.BuildInfo.version}")
   )
 
   def defaultInitPipeline(cfg: NettyConfig)(pipeline: ChannelPipeline, handler: ChannelHandler): Unit = {

server/netty-server/src/main/scala/sttp/tapir/server/netty/NettyFutureServer.scala

@@ -71,7 +71,7 @@ case class NettyFutureServer(routes: Vector[FutureRoute], options: NettyFutureSe
     val channelFuture =
       NettyBootstrap(
         config,
-        new NettyServerHandler(route, unsafeRunAsync, channelGroup, isShuttingDown),
+        new NettyServerHandler(route, unsafeRunAsync, channelGroup, isShuttingDown, config.serverHeader),
         eventLoopGroup,
         socketOverride
       )

server/netty-server/src/main/scala/sttp/tapir/server/netty/internal/NettyServerHandler.scala

@@ -7,7 +7,7 @@ import io.netty.handler.codec.http._
 import io.netty.handler.stream.{ChunkedFile, ChunkedStream}
 import org.playframework.netty.http.{DefaultStreamedHttpResponse, StreamedHttpRequest}
 import org.reactivestreams.Publisher
-import org.slf4j.{Logger, LoggerFactory}
+import org.slf4j.LoggerFactory
 import sttp.monad.MonadError
 import sttp.monad.syntax._
 import sttp.tapir.server.model.ServerResponse
@@ -35,7 +35,8 @@ class NettyServerHandler[F[_]](
     route: Route[F],
     unsafeRunAsync: (() => F[ServerResponse[NettyResponse]]) => (Future[ServerResponse[NettyResponse]], () => Future[Unit]),
     channelGroup: ChannelGroup,
-    isShuttingDown: AtomicBoolean
+    isShuttingDown: AtomicBoolean,
+    serverHeader: Option[String]
 )(implicit
     me: MonadError[F]
 ) extends SimpleChannelInboundHandler[HttpRequest] {
@@ -80,12 +81,9 @@ class NettyServerHandler[F[_]](
       // Since the listener will be executed from the channels EventLoop everything is thread safe.
       val _ = ctx.channel.closeFuture.addListener { (_: ChannelFuture) =>
         if (logger.isDebugEnabled) {
-          logger.debug("Http channel to {} closed. Cancelling {} responses.",
-            ctx.channel.remoteAddress,
-            pendingResponses.length
-          )
+          logger.debug("Http channel to {} closed. Cancelling {} responses.", ctx.channel.remoteAddress, pendingResponses.length)
         }
-        while(pendingResponses.nonEmpty) {
+        while (pendingResponses.nonEmpty) {
           pendingResponses.dequeue().apply()
         }
       }
@@ -256,6 +254,7 @@ class NettyServerHandler[F[_]](
 
   private implicit class RichHttpMessage(val m: HttpMessage) {
     def setHeadersFrom(response: ServerResponse[_]): Unit = {
+      serverHeader.foreach(m.headers().set(HttpHeaderNames.SERVER, _))
       response.headers
         .groupBy(_.name)
         .foreach { case (k, v) =>

server/netty-server/zio/src/main/scala/sttp/tapir/server/netty/zio/NettyZioServer.scala

@@ -91,7 +91,8 @@ case class NettyZioServer[R](routes: Vector[RIO[R, Route[RIO[R, *]]]], options:
           route,
           unsafeRunAsync(runtime),
           channelGroup,
-          isShuttingDown
+          isShuttingDown,
+          config.serverHeader
         ),
         eventLoopGroup,
         socketOverride