Auto-configure Micrometer’s Tomcat metrics

Closes gh-11916

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

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2012-2018 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
+ *
+ *      http://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.actuate.autoconfigure.metrics.web.tomcat;
+
+import java.util.Collections;
+
+import io.micrometer.core.instrument.binder.tomcat.TomcatMetrics;
+import org.apache.catalina.Container;
+import org.apache.catalina.Context;
+import org.apache.catalina.Manager;
+
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
+import org.springframework.boot.web.context.WebServerApplicationContext;
+import org.springframework.boot.web.embedded.tomcat.TomcatWebServer;
+import org.springframework.boot.web.server.WebServer;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.annotation.Bean;
+
+/**
+ * {@link EnableAutoConfiguration Auto-configuration} for {@link TomcatMetrics}.
+ *
+ * @author Andy Wilkinson
+ * @since 2.0.0
+ */
+@ConditionalOnWebApplication
+@ConditionalOnClass({ TomcatMetrics.class, Manager.class })
+public class TomcatMetricsAutoConfiguration {
+
+	@Bean
+	@ConditionalOnMissingBean(TomcatMetrics.class)
+	public TomcatMetrics tomcatMetrics(ApplicationContext applicationContext) {
+		Context context = findContext(applicationContext);
+		return new TomcatMetrics(context == null ? null : context.getManager(),
+				Collections.emptyList());
+	}
+
+	private Context findContext(ApplicationContext context) {
+		if (!(context instanceof WebServerApplicationContext)) {
+			return null;
+		}
+		WebServer webServer = ((WebServerApplicationContext) context).getWebServer();
+		if (!(webServer instanceof TomcatWebServer)) {
+			return null;
+		}
+		return findContext((TomcatWebServer) webServer);
+	}
+
+	private Context findContext(TomcatWebServer webServer) {
+		for (Container child : webServer.getTomcat().getHost().findChildren()) {
+			if (child instanceof Context) {
+				return (Context) child;
+			}
+		}
+		return null;
+	}
+
+}

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

@@ -52,6 +52,7 @@ org.springframework.boot.actuate.autoconfigure.metrics.integration.MetricsIntegr
 org.springframework.boot.actuate.autoconfigure.metrics.web.client.RestTemplateMetricsAutoConfiguration,\
 org.springframework.boot.actuate.autoconfigure.metrics.web.reactive.WebFluxMetricsAutoConfiguration,\
 org.springframework.boot.actuate.autoconfigure.metrics.web.servlet.WebMvcMetricsAutoConfiguration,\
+org.springframework.boot.actuate.autoconfigure.metrics.web.tomcat.TomcatMetricsAutoConfiguration,\
 org.springframework.boot.actuate.autoconfigure.mongo.MongoHealthIndicatorAutoConfiguration,\
 org.springframework.boot.actuate.autoconfigure.neo4j.Neo4jHealthIndicatorAutoConfiguration,\
 org.springframework.boot.actuate.autoconfigure.redis.RedisHealthIndicatorAutoConfiguration,\

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

@@ -0,0 +1,137 @@
+/*
+ * Copyright 2012-2018 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
+ *
+ *      http://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.actuate.autoconfigure.metrics.web.tomcat;
+
+import java.util.Collections;
+
+import io.micrometer.core.instrument.binder.tomcat.TomcatMetrics;
+import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
+import org.junit.Test;
+
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.runner.ReactiveWebApplicationContextRunner;
+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.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 static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Tests for {@link TomcatMetricsAutoConfiguration}.
+ *
+ * @author Andy Wilkinson
+ */
+public class TomcatMetricsAutoConfigurationTests {
+
+	@Test
+	public void autoConfiguresTomcatMetricsWithEmbeddedServletTomcat() {
+		new WebApplicationContextRunner(
+				AnnotationConfigServletWebServerApplicationContext::new)
+						.withConfiguration(AutoConfigurations
+								.of(TomcatMetricsAutoConfiguration.class))
+						.withUserConfiguration(ServletWebServerConfiguration.class)
+						.run((context) -> {
+							assertThat(context).hasSingleBean(TomcatMetrics.class);
+							SimpleMeterRegistry registry = new SimpleMeterRegistry();
+							context.getBean(TomcatMetrics.class).bindTo(registry);
+							assertThat(
+									registry.find("tomcat.sessions.active.max").meter())
+											.isNotNull();
+							assertThat(registry.find("tomcat.threads.current").meter())
+									.isNotNull();
+						});
+	}
+
+	@Test
+	public void autoConfiguresTomcatMetricsWithEmbeddedReactiveTomcat() {
+		new ReactiveWebApplicationContextRunner(
+				AnnotationConfigReactiveWebServerApplicationContext::new)
+						.withConfiguration(AutoConfigurations
+								.of(TomcatMetricsAutoConfiguration.class))
+						.withUserConfiguration(ReactiveWebServerConfiguration.class)
+						.run((context) -> {
+							assertThat(context).hasSingleBean(TomcatMetrics.class);
+							SimpleMeterRegistry registry = new SimpleMeterRegistry();
+							context.getBean(TomcatMetrics.class).bindTo(registry);
+							assertThat(
+									registry.find("tomcat.sessions.active.max").meter())
+											.isNotNull();
+							assertThat(registry.find("tomcat.threads.current").meter())
+									.isNotNull();
+						});
+	}
+
+	@Test
+	public void autoConfiguresTomcatMetricsWithStandaloneTomcat() {
+		new WebApplicationContextRunner()
+				.withConfiguration(
+						AutoConfigurations.of(TomcatMetricsAutoConfiguration.class))
+				.run((context) -> assertThat(context).hasSingleBean(TomcatMetrics.class));
+	}
+
+	@Test
+	public void allowsCustomTomcatMetricsToBeUsed() {
+		new WebApplicationContextRunner()
+				.withConfiguration(
+						AutoConfigurations.of(TomcatMetricsAutoConfiguration.class))
+				.withUserConfiguration(CustomTomcatMetrics.class)
+				.run((context) -> assertThat(context).hasSingleBean(TomcatMetrics.class)
+						.hasBean("customTomcatMetrics"));
+	}
+
+	@Configuration
+	static class ServletWebServerConfiguration {
+
+		@Bean
+		public TomcatServletWebServerFactory tomcatFactory() {
+			return new TomcatServletWebServerFactory(0);
+		}
+
+	}
+
+	@Configuration
+	static class ReactiveWebServerConfiguration {
+
+		@Bean
+		public TomcatReactiveWebServerFactory tomcatFactory() {
+			return new TomcatReactiveWebServerFactory(0);
+		}
+
+		@Bean
+		public HttpHandler httpHandler() {
+			return mock(HttpHandler.class);
+		}
+
+	}
+
+	@Configuration
+	static class CustomTomcatMetrics {
+
+		@Bean
+		public TomcatMetrics customTomcatMetrics() {
+			return new TomcatMetrics(null, Collections.emptyList());
+		}
+
+	}
+
+}