Disable Tomcat's MBean Registry by default

Closes gh-16498

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/web/reactive/ReactiveManagementChildContextConfiguration.java

@@ -27,6 +27,7 @@ import org.springframework.boot.autoconfigure.web.embedded.NettyWebServerFactory
 import org.springframework.boot.autoconfigure.web.embedded.TomcatWebServerFactoryCustomizer;
 import org.springframework.boot.autoconfigure.web.embedded.UndertowWebServerFactoryCustomizer;
 import org.springframework.boot.autoconfigure.web.reactive.ReactiveWebServerFactoryCustomizer;
+import org.springframework.boot.autoconfigure.web.reactive.TomcatReactiveWebServerFactoryCustomizer;
 import org.springframework.boot.web.reactive.server.ConfigurableReactiveWebServerFactory;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
@@ -65,6 +66,7 @@ public class ReactiveManagementChildContextConfiguration {
 		ReactiveManagementWebServerFactoryCustomizer(ListableBeanFactory beanFactory) {
 			super(beanFactory, ReactiveWebServerFactoryCustomizer.class,
 					TomcatWebServerFactoryCustomizer.class,
+					TomcatReactiveWebServerFactoryCustomizer.class,
 					JettyWebServerFactoryCustomizer.class,
 					UndertowWebServerFactoryCustomizer.class,
 					NettyWebServerFactoryCustomizer.class);

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/web/tomcat/TomcatMetricsAutoConfigurationTests.java

@@ -17,10 +17,12 @@
 package org.springframework.boot.actuate.autoconfigure.metrics.web.tomcat;
 
 import java.util.Collections;
+import java.util.concurrent.atomic.AtomicInteger;
 
 import io.micrometer.core.instrument.MeterRegistry;
 import io.micrometer.core.instrument.binder.tomcat.TomcatMetrics;
 import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
+import org.apache.tomcat.util.modeler.Registry;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.SpringApplication;
@@ -33,11 +35,13 @@ import org.springframework.boot.test.context.runner.ReactiveWebApplicationContex
 import org.springframework.boot.test.context.runner.WebApplicationContextRunner;
 import org.springframework.boot.web.embedded.tomcat.TomcatReactiveWebServerFactory;
 import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;
+import org.springframework.boot.web.embedded.tomcat.TomcatWebServer;
 import org.springframework.boot.web.reactive.context.AnnotationConfigReactiveWebServerApplicationContext;
 import org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.http.server.reactive.HttpHandler;
+import org.springframework.test.util.ReflectionTestUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.mock;
@@ -51,6 +55,7 @@ public class TomcatMetricsAutoConfigurationTests {
 
 	@Test
 	public void autoConfiguresTomcatMetricsWithEmbeddedServletTomcat() {
+		resetTomcatState();
 		new WebApplicationContextRunner(
 				AnnotationConfigServletWebServerApplicationContext::new)
 						.withConfiguration(AutoConfigurations.of(
@@ -58,6 +63,7 @@ public class TomcatMetricsAutoConfigurationTests {
 								ServletWebServerFactoryAutoConfiguration.class))
 						.withUserConfiguration(ServletWebServerConfiguration.class,
 								MeterRegistryConfiguration.class)
+						.withPropertyValues("server.tomcat.mbeanregistry.enabled=true")
 						.run((context) -> {
 							context.publishEvent(
 									new ApplicationStartedEvent(new SpringApplication(),
@@ -75,6 +81,7 @@ public class TomcatMetricsAutoConfigurationTests {
 
 	@Test
 	public void autoConfiguresTomcatMetricsWithEmbeddedReactiveTomcat() {
+		resetTomcatState();
 		new ReactiveWebApplicationContextRunner(
 				AnnotationConfigReactiveWebServerApplicationContext::new)
 						.withConfiguration(AutoConfigurations.of(
@@ -82,6 +89,7 @@ public class TomcatMetricsAutoConfigurationTests {
 								ReactiveWebServerFactoryAutoConfiguration.class))
 						.withUserConfiguration(ReactiveWebServerConfiguration.class,
 								MeterRegistryConfiguration.class)
+						.withPropertyValues("server.tomcat.mbeanregistry.enabled=true")
 						.run((context) -> {
 							context.publishEvent(
 									new ApplicationStartedEvent(new SpringApplication(),
@@ -130,6 +138,13 @@ public class TomcatMetricsAutoConfigurationTests {
 						.hasBean("customTomcatMetrics"));
 	}
 
+	private void resetTomcatState() {
+		ReflectionTestUtils.setField(Registry.class, "registry", null);
+		AtomicInteger containerCounter = (AtomicInteger) ReflectionTestUtils
+				.getField(TomcatWebServer.class, "containerCounter");
+		containerCounter.set(-1);
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class MeterRegistryConfiguration {
 

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/BackgroundPreinitializer.java

@@ -23,8 +23,6 @@ import java.util.concurrent.atomic.AtomicBoolean;
 import javax.validation.Configuration;
 import javax.validation.Validation;
 
-import org.apache.catalina.mbeans.MBeanFactory;
-
 import org.springframework.boot.context.event.ApplicationFailedEvent;
 import org.springframework.boot.context.event.ApplicationReadyEvent;
 import org.springframework.boot.context.event.ApplicationStartingEvent;
@@ -99,7 +97,6 @@ public class BackgroundPreinitializer
 					runSafely(new ConversionServiceInitializer());
 					runSafely(new ValidationInitializer());
 					runSafely(new MessageConverterInitializer());
-					runSafely(new MBeanFactoryInitializer());
 					runSafely(new JacksonInitializer());
 					runSafely(new CharsetInitializer());
 					preinitializationComplete.countDown();
@@ -137,18 +134,6 @@ public class BackgroundPreinitializer
 
 	}
 
-	/**
-	 * Early initializer to load Tomcat MBean XML.
-	 */
-	private static class MBeanFactoryInitializer implements Runnable {
-
-		@Override
-		public void run() {
-			new MBeanFactory();
-		}
-
-	}
-
 	/**
 	 * Early initializer for javax.validation.
 	 */

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/ServerProperties.java

@@ -400,6 +400,11 @@ public class ServerProperties {
 		 */
 		private final Resource resource = new Resource();
 
+		/**
+		 * Modeler MBean Registry configuration.
+		 */
+		private final Mbeanregistry mbeanregistry = new Mbeanregistry();
+
 		public int getMaxThreads() {
 			return this.maxThreads;
 		}
@@ -552,6 +557,10 @@ public class ServerProperties {
 			return this.resource;
 		}
 
+		public Mbeanregistry getMbeanregistry() {
+			return this.mbeanregistry;
+		}
+
 		/**
 		 * Tomcat access log properties.
 		 */
@@ -821,6 +830,23 @@ public class ServerProperties {
 
 		}
 
+		public static class Mbeanregistry {
+
+			/**
+			 * Whether Tomcat's MBean Registry should be enabled.
+			 */
+			private boolean enabled;
+
+			public boolean isEnabled() {
+				return this.enabled;
+			}
+
+			public void setEnabled(boolean enabled) {
+				this.enabled = enabled;
+			}
+
+		}
+
 	}
 
 	/**

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/reactive/ReactiveWebServerFactoryConfiguration.java

@@ -24,6 +24,7 @@ import reactor.netty.http.server.HttpServer;
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.web.ServerProperties;
 import org.springframework.boot.web.embedded.jetty.JettyReactiveWebServerFactory;
 import org.springframework.boot.web.embedded.jetty.JettyServerCustomizer;
 import org.springframework.boot.web.embedded.netty.NettyReactiveWebServerFactory;
@@ -98,6 +99,12 @@ abstract class ReactiveWebServerFactoryConfiguration {
 			return factory;
 		}
 
+		@Bean
+		public TomcatReactiveWebServerFactoryCustomizer tomcatReactiveWebServerFactoryCustomizer(
+				ServerProperties serverProperties) {
+			return new TomcatReactiveWebServerFactoryCustomizer(serverProperties);
+		}
+
 	}
 
 	@Configuration(proxyBeanMethods = false)

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/reactive/TomcatReactiveWebServerFactoryCustomizer.java

@@ -0,0 +1,48 @@
+/*
+ * 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.autoconfigure.web.reactive;
+
+import org.apache.tomcat.util.modeler.Registry;
+
+import org.springframework.boot.autoconfigure.web.ServerProperties;
+import org.springframework.boot.web.embedded.tomcat.TomcatReactiveWebServerFactory;
+import org.springframework.boot.web.server.WebServerFactoryCustomizer;
+
+/**
+ * {@link WebServerFactoryCustomizer} to apply {@link ServerProperties} to Tomcat reactive
+ * web servers.
+ *
+ * @author Andy Wilkinson
+ * @since 2.2.0
+ */
+public class TomcatReactiveWebServerFactoryCustomizer
+		implements WebServerFactoryCustomizer<TomcatReactiveWebServerFactory> {
+
+	private final ServerProperties serverProperties;
+
+	public TomcatReactiveWebServerFactoryCustomizer(ServerProperties serverProperties) {
+		this.serverProperties = serverProperties;
+	}
+
+	@Override
+	public void customize(TomcatReactiveWebServerFactory factory) {
+		if (!this.serverProperties.getTomcat().getMbeanregistry().isEnabled()) {
+			Registry.disableRegistry();
+		}
+	}
+
+}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/TomcatServletWebServerFactoryCustomizer.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.autoconfigure.web.servlet;
 
+import org.apache.tomcat.util.modeler.Registry;
+
 import org.springframework.boot.autoconfigure.web.ServerProperties;
 import org.springframework.boot.web.embedded.tomcat.ConfigurableTomcatWebServerFactory;
 import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;
@@ -60,6 +62,9 @@ public class TomcatServletWebServerFactoryCustomizer
 			customizeUseRelativeRedirects(factory,
 					tomcatProperties.getUseRelativeRedirects());
 		}
+		if (!tomcatProperties.getMbeanregistry().isEnabled()) {
+			Registry.disableRegistry();
+		}
 	}
 
 	private void customizeRedirectContextRoot(ConfigurableTomcatWebServerFactory factory,

spring-boot-project/spring-boot-docs/src/main/asciidoc/howto.adoc

@@ -1075,6 +1075,20 @@ include::{code-examples}/context/embedded/TomcatLegacyCookieProcessorExample.jav
 
 
 
+[[howto-enable-tomcat-mbean-registry]]
+=== Enable Tomcat's MBean Registry
+Embedded Tomcat's MBean registry is disabled by default. This minimizes Tomcat's memory
+footprint. If you want to use Tomcat's MBeans, for example so that they can be used to
+expose metrics via Micrometer, you must use the `server.tomcat.mbeanregistry.enabled`
+property to do so, as shown in the following example:
+
+[source,properties,indent=0]
+----
+server.tomcat.mbeanregistry.enabled=true
+----
+
+
+
 [[howto-enable-multiple-listeners-in-undertow]]
 === Enable Multiple Listeners with Undertow
 Add an `UndertowBuilderCustomizer` to the `UndertowServletWebServerFactory` and

spring-boot-project/spring-boot-docs/src/main/asciidoc/production-ready-features.adoc

@@ -1793,7 +1793,8 @@ Spring Boot registers the following core metrics when applicable:
 * Logback metrics: record the number of events logged to Logback at each level
 * Uptime metrics: report a gauge for uptime and a fixed gauge representing the
 application's absolute start time
-* Tomcat metrics
+* Tomcat metrics (`server.tomcat.mbeanregistry.enabled` must be set to `true` for all
+Tomcat metrics to be registered)
 * https://docs.spring.io/spring-integration/docs/current/reference/html/system-management-chapter.html#micrometer-integration[Spring Integration] metrics