Deal with unsupported DisposableServer operations

Update `NettyWebServer` to deal with any `UnsupportedOperationException`
thrown from `DisposableServer`. Specifically, this commit allows the
`NettyWebServer` to work with domain socket backed servers which cannot
provide a port.

Fixes gh-24529

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/netty/NettyReactiveWebServerFactory.java

@@ -69,11 +69,17 @@ public NettyReactiveWebServerFactory(int port) {
 	public WebServer getWebServer(HttpHandler httpHandler) {
 		HttpServer httpServer = createHttpServer();
 		ReactorHttpHandlerAdapter handlerAdapter = new ReactorHttpHandlerAdapter(httpHandler);
-		NettyWebServer webServer = new NettyWebServer(httpServer, handlerAdapter, this.lifecycleTimeout, getShutdown());
+		NettyWebServer webServer = createNettyWebServer(httpServer, handlerAdapter, this.lifecycleTimeout,
+				getShutdown());
 		webServer.setRouteProviders(this.routeProviders);
 		return webServer;
 	}
 
+	NettyWebServer createNettyWebServer(HttpServer httpServer, ReactorHttpHandlerAdapter handlerAdapter,
+			Duration lifecycleTimeout, Shutdown shutdown) {
+		return new NettyWebServer(httpServer, handlerAdapter, lifecycleTimeout, shutdown);
+	}
+
 	/**
 	 * Returns a mutable collection of the {@link NettyServerCustomizer}s that will be
 	 * applied to the Netty server builder.

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/netty/NettyWebServer.java

@@ -21,6 +21,7 @@
 import java.util.List;
 import java.util.function.BiFunction;
 import java.util.function.Predicate;
+import java.util.function.Supplier;
 
 import io.netty.channel.group.DefaultChannelGroup;
 import io.netty.channel.unix.Errors.NativeIoException;
@@ -106,11 +107,44 @@ public void start() throws WebServerException {
 				});
 				throw new WebServerException("Unable to start Netty", ex);
 			}
-			logger.info("Netty started on port(s): " + getPort());
+			if (this.disposableServer != null) {
+				logger.info("Netty started" + getStartedOnMessage(this.disposableServer));
+			}
 			startDaemonAwaitThread(this.disposableServer);
 		}
 	}
 
+	private String getStartedOnMessage(DisposableServer server) {
+		StringBuilder message = new StringBuilder();
+		tryAppend(message, "port %s", () -> server.port());
+		tryAppend(message, "path %s", () -> server.path());
+		return (message.length() > 0) ? " on " + message : "";
+	}
+
+	private void tryAppend(StringBuilder message, String format, Supplier<Object> supplier) {
+		try {
+			Object value = supplier.get();
+			message.append((message.length() != 0) ? " " : "");
+			message.append(String.format(format, value));
+		}
+		catch (UnsupportedOperationException ex) {
+		}
+	}
+
+	DisposableServer startHttpServer() {
+		HttpServer server = this.httpServer;
+		if (this.routeProviders.isEmpty()) {
+			server = server.handle(this.handler);
+		}
+		else {
+			server = server.route(this::applyRouteProviders);
+		}
+		if (this.lifecycleTimeout != null) {
+			return server.bindNow(this.lifecycleTimeout);
+		}
+		return server.bindNow();
+	}
+
 	private boolean isPermissionDenied(Throwable bindExceptionCause) {
 		try {
 			if (bindExceptionCause instanceof NativeIoException) {
@@ -131,20 +165,6 @@ public void shutDownGracefully(GracefulShutdownCallback callback) {
 		this.gracefulShutdown.shutDownGracefully(callback);
 	}
 
-	private DisposableServer startHttpServer() {
-		HttpServer server = this.httpServer;
-		if (this.routeProviders.isEmpty()) {
-			server = server.handle(this.handler);
-		}
-		else {
-			server = server.route(this::applyRouteProviders);
-		}
-		if (this.lifecycleTimeout != null) {
-			return server.bindNow(this.lifecycleTimeout);
-		}
-		return server.bindNow();
-	}
-
 	private void applyRouteProviders(HttpServerRoutes routes) {
 		for (NettyRouteProvider provider : this.routeProviders) {
 			routes = provider.apply(routes);
@@ -190,7 +210,12 @@ public void stop() throws WebServerException {
 	@Override
 	public int getPort() {
 		if (this.disposableServer != null) {
-			return this.disposableServer.port();
+			try {
+				return this.disposableServer.port();
+			}
+			catch (UnsupportedOperationException ex) {
+				return -1;
+			}
 		}
 		return 0;
 	}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/embedded/netty/NettyReactiveWebServerFactoryTests.java

@@ -17,13 +17,19 @@
 package org.springframework.boot.web.embedded.netty;
 
 import java.net.ConnectException;
+import java.net.SocketAddress;
 import java.time.Duration;
 import java.util.Arrays;
 
+import io.netty.channel.Channel;
 import org.awaitility.Awaitility;
 import org.junit.jupiter.api.Test;
 import org.mockito.InOrder;
+import reactor.core.CoreSubscriber;
+import reactor.core.Disposable;
 import reactor.core.publisher.Mono;
+import reactor.netty.DisposableChannel;
+import reactor.netty.DisposableServer;
 import reactor.netty.http.server.HttpServer;
 import reactor.test.StepVerifier;
 
@@ -34,6 +40,7 @@
 import org.springframework.boot.web.server.Ssl;
 import org.springframework.http.MediaType;
 import org.springframework.http.client.reactive.ReactorClientHttpConnector;
+import org.springframework.http.server.reactive.ReactorHttpHandlerAdapter;
 import org.springframework.web.reactive.function.BodyInserters;
 import org.springframework.web.reactive.function.client.WebClient;
 
@@ -52,11 +59,6 @@
  */
 class NettyReactiveWebServerFactoryTests extends AbstractReactiveWebServerFactoryTests {
 
-	@Override
-	protected NettyReactiveWebServerFactory getFactory() {
-		return new NettyReactiveWebServerFactory(0);
-	}
-
 	@Test
 	void exceptionIsThrownWhenPortIsAlreadyInUse() {
 		AbstractReactiveWebServerFactory factory = getFactory();
@@ -68,6 +70,14 @@ void exceptionIsThrownWhenPortIsAlreadyInUse() {
 				.satisfies(this::portMatchesRequirement).withCauseInstanceOf(Throwable.class);
 	}
 
+	@Test
+	void getPortWhenDisposableServerPortOperationIsUnsupportedReturnsMinusOne() {
+		NettyReactiveWebServerFactory factory = new NoPortNettyReactiveWebServerFactory(0);
+		this.webServer = factory.getWebServer(new EchoHandler());
+		this.webServer.start();
+		assertThat(this.webServer.getPort()).isEqualTo(-1);
+	}
+
 	private void portMatchesRequirement(PortInUseException exception) {
 		assertThat(exception.getPort()).isEqualTo(this.webServer.getPort());
 	}
@@ -143,4 +153,102 @@ protected Mono<String> testSslWithAlias(String alias) {
 				.retrieve().bodyToMono(String.class);
 	}
 
+	@Override
+	protected NettyReactiveWebServerFactory getFactory() {
+		return new NettyReactiveWebServerFactory(0);
+	}
+
+	static class NoPortNettyReactiveWebServerFactory extends NettyReactiveWebServerFactory {
+
+		NoPortNettyReactiveWebServerFactory(int port) {
+			super(port);
+		}
+
+		@Override
+		NettyWebServer createNettyWebServer(HttpServer httpServer, ReactorHttpHandlerAdapter handlerAdapter,
+				Duration lifecycleTimeout, Shutdown shutdown) {
+			return new NoPortNettyWebServer(httpServer, handlerAdapter, lifecycleTimeout, shutdown);
+		}
+
+	}
+
+	static class NoPortNettyWebServer extends NettyWebServer {
+
+		NoPortNettyWebServer(HttpServer httpServer, ReactorHttpHandlerAdapter handlerAdapter, Duration lifecycleTimeout,
+				Shutdown shutdown) {
+			super(httpServer, handlerAdapter, lifecycleTimeout, shutdown);
+		}
+
+		@Override
+		DisposableServer startHttpServer() {
+			return new NoPortDisposableServer(super.startHttpServer());
+		}
+
+	}
+
+	static class NoPortDisposableServer implements DisposableServer {
+
+		private final DisposableServer delegate;
+
+		NoPortDisposableServer(DisposableServer delegate) {
+			this.delegate = delegate;
+		}
+
+		@Override
+		public SocketAddress address() {
+			return this.delegate.address();
+		}
+
+		@Override
+		public String host() {
+			return this.delegate.host();
+		}
+
+		@Override
+		public String path() {
+			return this.delegate.path();
+		}
+
+		@Override
+		public Channel channel() {
+			return this.delegate.channel();
+		}
+
+		@Override
+		public void dispose() {
+			this.delegate.dispose();
+		}
+
+		@Override
+		public void disposeNow() {
+			this.delegate.disposeNow();
+		}
+
+		@Override
+		public void disposeNow(Duration timeout) {
+			this.delegate.disposeNow(timeout);
+		}
+
+		@Override
+		public CoreSubscriber<Void> disposeSubscriber() {
+			return this.delegate.disposeSubscriber();
+		}
+
+		@Override
+		public boolean isDisposed() {
+			return this.delegate.isDisposed();
+		}
+
+		@Override
+		public Mono<Void> onDispose() {
+			return this.delegate.onDispose();
+		}
+
+		@Override
+		public DisposableChannel onDispose(Disposable onDispose) {
+			return this.delegate.onDispose(onDispose);
+		}
+
+	}
+
 }