Add @LocalRSocketServerPort support

Add an appication context initializer to detect and store the
active RSocket port in the Environment under
`local.rsocket.server.port`.

Additionally add a `@LocalServerPort` that provides a convenient
alternative to `@Value`.

See gh-18287

Co-authored-by: Eddú Meléndez <eddu.melendez@gmail.com>

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/rsocket/RSocketServerAutoConfigurationTests.java

@@ -24,6 +24,7 @@ import org.springframework.boot.rsocket.server.RSocketServerFactory;
 import org.springframework.boot.rsocket.server.ServerRSocketFactoryCustomizer;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.boot.test.context.runner.ReactiveWebApplicationContextRunner;
+import org.springframework.boot.web.context.RSocketPortInfoApplicationContextInitializer;
 import org.springframework.boot.web.server.WebServerFactoryCustomizer;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -39,6 +40,7 @@ import static org.mockito.Mockito.mock;
  * Tests for {@link RSocketServerAutoConfiguration}.
  *
  * @author Brian Clozel
+ * @author Verónica Vásquez
  */
 class RSocketServerAutoConfigurationTests {
 
@@ -80,6 +82,17 @@ class RSocketServerAutoConfigurationTests {
 						.hasSingleBean(ServerRSocketFactoryCustomizer.class));
 	}
 
+	@Test
+	void shouldSetLocalServerPortWhenRSocketServerPortIsSet() {
+		reactiveWebContextRunner().withPropertyValues("spring.rsocket.server.port=0")
+				.withInitializer(new RSocketPortInfoApplicationContextInitializer()).run((context) -> {
+					assertThat(context).hasSingleBean(RSocketServerFactory.class)
+							.hasSingleBean(RSocketServerBootstrap.class)
+							.hasSingleBean(ServerRSocketFactoryCustomizer.class);
+					assertThat(context.getEnvironment().getProperty("local.rsocket.server.port")).isNotNull();
+				});
+	}
+
 	@Test
 	void shouldUseCustomServerBootstrap() {
 		contextRunner().withUserConfiguration(CustomServerBootstrapConfig.class).run((context) -> assertThat(context)

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/context/RSocketPortInfoApplicationContextInitializer.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2012-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.web.context;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.rsocket.context.RSocketServerInitializedEvent;
+import org.springframework.boot.rsocket.server.RSocketServer;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ApplicationContextInitializer;
+import org.springframework.context.ApplicationListener;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.core.env.Environment;
+import org.springframework.core.env.MapPropertySource;
+import org.springframework.core.env.MutablePropertySources;
+import org.springframework.core.env.PropertySource;
+
+/**
+ * {@link ApplicationContextInitializer} that sets {@link Environment} properties for the
+ * ports that {@link RSocketServer} servers are actually listening on. The property
+ * {@literal "local.rsocket.server.port"} can be injected directly into tests using
+ * {@link Value @Value} or obtained via the {@link Environment}.
+ * <p>
+ * Properties are automatically propagated up to any parent context.
+ *
+ * @author Verónica Vásquez
+ * @author Eddú Meléndez
+ * @since 2.2.0
+ */
+public class RSocketPortInfoApplicationContextInitializer
+		implements ApplicationContextInitializer<ConfigurableApplicationContext>,
+		ApplicationListener<RSocketServerInitializedEvent> {
+
+	private ConfigurableApplicationContext applicationContext;
+
+	@Override
+	public void initialize(ConfigurableApplicationContext applicationContext) {
+		applicationContext.addApplicationListener(this);
+		this.applicationContext = applicationContext;
+	}
+
+	@Override
+	public void onApplicationEvent(RSocketServerInitializedEvent event) {
+		String propertyName = "local.rsocket.server.port";
+		setPortProperty(this.applicationContext, propertyName, event.getrSocketServer().address().getPort());
+	}
+
+	private void setPortProperty(ApplicationContext context, String propertyName, int port) {
+		if (context instanceof ConfigurableApplicationContext) {
+			setPortProperty(((ConfigurableApplicationContext) context).getEnvironment(), propertyName, port);
+		}
+		if (context.getParent() != null) {
+			setPortProperty(context.getParent(), propertyName, port);
+		}
+	}
+
+	@SuppressWarnings("unchecked")
+	private void setPortProperty(ConfigurableEnvironment environment, String propertyName, int port) {
+		MutablePropertySources sources = environment.getPropertySources();
+		PropertySource<?> source = sources.get("server.ports");
+		if (source == null) {
+			source = new MapPropertySource("server.ports", new HashMap<>());
+			sources.addFirst(source);
+		}
+		((Map<String, Object>) source.getSource()).put(propertyName, port);
+	}
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/server/LocalRSocketServerPort.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2012-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.web.server;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.beans.factory.annotation.Value;
+
+/**
+ * Annotation at the field or method/constructor parameter level that injects the RSocket
+ * port that got allocated at runtime. Provides a convenient alternative for
+ * <code>&#064;Value(&quot;${local.rsocket.server.port}&quot;)</code>.
+ *
+ * @author Verónica Vásquez
+ * @author Eddú Meléndez
+ * @since 2.2.0
+ */
+@Target({ ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER, ElementType.ANNOTATION_TYPE })
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Value("${local.rsocket.server.port}")
+public @interface LocalRSocketServerPort {
+
+}

spring-boot-project/spring-boot/src/main/resources/META-INF/spring.factories

@@ -16,7 +16,8 @@ org.springframework.context.ApplicationContextInitializer=\
 org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer,\
 org.springframework.boot.context.ContextIdApplicationContextInitializer,\
 org.springframework.boot.context.config.DelegatingApplicationContextInitializer,\
-org.springframework.boot.web.context.ServerPortInfoApplicationContextInitializer
+org.springframework.boot.web.context.ServerPortInfoApplicationContextInitializer,\
+org.springframework.boot.web.context.RSocketPortInfoApplicationContextInitializer
 
 # Application Listeners
 org.springframework.context.ApplicationListener=\

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/builder/SpringApplicationBuilderTests.java

@@ -240,7 +240,7 @@ class SpringApplicationBuilderTests {
 		SpringApplicationBuilder application = new SpringApplicationBuilder(ExampleConfig.class)
 				.web(WebApplicationType.NONE);
 		this.context = application.run();
-		assertThat(application.application().getInitializers()).hasSize(4);
+		assertThat(application.application().getInitializers()).hasSize(5);
 	}
 
 	@Test
@@ -248,7 +248,7 @@ class SpringApplicationBuilderTests {
 		SpringApplicationBuilder application = new SpringApplicationBuilder(ExampleConfig.class)
 				.child(ChildConfig.class).web(WebApplicationType.NONE);
 		this.context = application.run();
-		assertThat(application.application().getInitializers()).hasSize(5);
+		assertThat(application.application().getInitializers()).hasSize(6);
 	}
 
 	@Test
@@ -257,7 +257,7 @@ class SpringApplicationBuilderTests {
 				.web(WebApplicationType.NONE).initializers((ConfigurableApplicationContext applicationContext) -> {
 				});
 		this.context = application.run();
-		assertThat(application.application().getInitializers()).hasSize(5);
+		assertThat(application.application().getInitializers()).hasSize(6);
 	}
 
 	@Test

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/server/LocalRSocketServerPortTests.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2012-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.web.server;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.test.context.TestPropertySource;
+import org.springframework.test.context.junit.jupiter.SpringExtension;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link LocalRSocketServerPort @LocalRSocketServerPort}.
+ *
+ * @author Verónica Vásquez
+ * @author Eddú Meléndez
+ */
+@ExtendWith(SpringExtension.class)
+@TestPropertySource(properties = "local.rsocket.server.port=8181")
+class LocalRSocketServerPortTests {
+
+	@Value("${local.rsocket.server.port}")
+	private String fromValue;
+
+	@LocalRSocketServerPort
+	private String fromAnnotation;
+
+	@Test
+	void testLocalRSocketServerPortAnnotation() {
+		assertThat(this.fromAnnotation).isNotNull().isEqualTo(this.fromValue);
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	static class Config {
+
+	}
+
+}