Add Tomcat public metrics for session usage

Fixes gh-1860

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/PublicMetricsAutoConfiguration.java

@@ -16,14 +16,17 @@
 
 package org.springframework.boot.actuate.autoconfigure;
 
+import javax.servlet.Servlet;
 import javax.sql.DataSource;
 
+import org.apache.catalina.startup.Tomcat;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.actuate.endpoint.DataSourcePublicMetrics;
 import org.springframework.boot.actuate.endpoint.MetricReaderPublicMetrics;
 import org.springframework.boot.actuate.endpoint.PublicMetrics;
 import org.springframework.boot.actuate.endpoint.RichGaugeReaderPublicMetrics;
 import org.springframework.boot.actuate.endpoint.SystemPublicMetrics;
+import org.springframework.boot.actuate.endpoint.TomcatPublicMetrics;
 import org.springframework.boot.actuate.metrics.reader.MetricReader;
 import org.springframework.boot.actuate.metrics.repository.InMemoryMetricRepository;
 import org.springframework.boot.actuate.metrics.rich.RichGaugeReader;
@@ -43,6 +46,7 @@ import org.springframework.context.annotation.Configuration;
  *
  * @author Stephane Nicoll
  * @author Phillip Webb
+ * @author Johannes Stelzer
  * @since 1.2.0
  */
 @Configuration
@@ -71,7 +75,6 @@ public class PublicMetricsAutoConfiguration {
 		return new RichGaugeReaderPublicMetrics(richGaugeReader);
 	}
 
-	@Configuration
 	@ConditionalOnClass(DataSource.class)
 	@ConditionalOnBean(DataSource.class)
 	static class DataSourceMetricsConfiguration {
@@ -85,4 +88,15 @@ public class PublicMetricsAutoConfiguration {
 
 	}
 
+	@ConditionalOnClass({ Servlet.class, Tomcat.class })
+	static class TomcatMetricsConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean
+		public TomcatPublicMetrics tomcatPublicMetrics() {
+			return new TomcatPublicMetrics();
+		}
+
+	}
+
 }

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/TomcatPublicMetrics.java

@@ -0,0 +1,89 @@
+/*
+ * Copyright 2012-2014 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.endpoint;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
+import org.apache.catalina.Container;
+import org.apache.catalina.Context;
+import org.apache.catalina.Manager;
+import org.springframework.beans.BeansException;
+import org.springframework.boot.actuate.metrics.Metric;
+import org.springframework.boot.context.embedded.EmbeddedServletContainer;
+import org.springframework.boot.context.embedded.EmbeddedWebApplicationContext;
+import org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainer;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ApplicationContextAware;
+
+/**
+ * A {@link PublicMetrics} implementation that provides Tomcat statistics.
+ *
+ * @author Johannes Stelzer
+ * @author Phillip Webb
+ * @since 1.2.0
+ */
+public class TomcatPublicMetrics implements PublicMetrics, ApplicationContextAware {
+
+	private ApplicationContext applicationContext;
+
+	@Override
+	public Collection<Metric<?>> metrics() {
+		if (this.applicationContext instanceof EmbeddedWebApplicationContext) {
+			Manager manager = getManager((EmbeddedWebApplicationContext) this.applicationContext);
+			if (manager != null) {
+				return metrics(manager);
+			}
+		}
+		return Collections.emptySet();
+	}
+
+	private Manager getManager(EmbeddedWebApplicationContext applicationContext) {
+		EmbeddedServletContainer embeddedServletContainer = applicationContext
+				.getEmbeddedServletContainer();
+		if (embeddedServletContainer instanceof TomcatEmbeddedServletContainer) {
+			return getManager((TomcatEmbeddedServletContainer) embeddedServletContainer);
+		}
+		return null;
+	}
+
+	private Manager getManager(TomcatEmbeddedServletContainer servletContainer) {
+		for (Container container : servletContainer.getTomcat().getHost().findChildren()) {
+			if (container instanceof Context) {
+				return ((Context) container).getManager();
+			}
+		}
+		return null;
+	}
+
+	private Collection<Metric<?>> metrics(Manager manager) {
+		List<Metric<?>> metrics = new ArrayList<Metric<?>>(2);
+		metrics.add(new Metric<Integer>("httpsessions.max", manager.getMaxActive()));
+		metrics.add(new Metric<Integer>("httpsessions.active", manager
+				.getActiveSessions()));
+		return metrics;
+	}
+
+	@Override
+	public void setApplicationContext(ApplicationContext applicationContext)
+			throws BeansException {
+		this.applicationContext = applicationContext;
+	}
+
+}

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/autoconfigure/PublicMetricsAutoConfigurationTests.java

@@ -33,12 +33,14 @@ import org.springframework.boot.actuate.endpoint.MetricReaderPublicMetrics;
 import org.springframework.boot.actuate.endpoint.PublicMetrics;
 import org.springframework.boot.actuate.endpoint.RichGaugeReaderPublicMetrics;
 import org.springframework.boot.actuate.endpoint.SystemPublicMetrics;
+import org.springframework.boot.actuate.endpoint.TomcatPublicMetrics;
 import org.springframework.boot.actuate.metrics.Metric;
 import org.springframework.boot.actuate.metrics.rich.RichGauge;
 import org.springframework.boot.actuate.metrics.rich.RichGaugeReader;
 import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
 import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
 import org.springframework.boot.autoconfigure.jdbc.metadata.DataSourcePoolMetadataProvidersConfiguration;
+import org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -46,6 +48,7 @@ import org.springframework.context.annotation.Primary;
 import org.springframework.dao.DataAccessException;
 import org.springframework.jdbc.core.ConnectionCallback;
 import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.util.SocketUtils;
 
 import com.zaxxer.hikari.HikariDataSource;
 
@@ -175,6 +178,12 @@ public class PublicMetricsAutoConfigurationTests {
 				"ds.second.usage");
 	}
 
+	@Test
+	public void tomcatMetrics() throws Exception {
+		load(TomcatConfiguration.class);
+		assertEquals(1, this.context.getBeansOfType(TomcatPublicMetrics.class).size());
+	}
+
 	private void assertHasMetric(Collection<Metric<?>> metrics, Metric<?> metric) {
 		for (Metric<?> m : metrics) {
 			if (m.getValue().equals(metric.getValue())
@@ -271,4 +280,16 @@ public class PublicMetricsAutoConfigurationTests {
 
 	}
 
+	@Configuration
+	static class TomcatConfiguration {
+
+		@Bean
+		public TomcatEmbeddedServletContainerFactory containerFactory() {
+			TomcatEmbeddedServletContainerFactory factory = new TomcatEmbeddedServletContainerFactory();
+			factory.setPort(SocketUtils.findAvailableTcpPort(40000));
+			return factory;
+		}
+
+	}
+
 }

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/TomcatPublicMetricsTests.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2012-2014 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.endpoint;
+
+import java.util.Iterator;
+
+import org.junit.Test;
+import org.springframework.boot.actuate.metrics.Metric;
+import org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext;
+import org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.util.SocketUtils;
+
+import static org.hamcrest.Matchers.equalTo;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Tests for {@link TomcatPublicMetrics}
+ *
+ * @author Johannes Stelzer
+ * @author Phillip Webb
+ */
+public class TomcatPublicMetricsTests {
+
+	@Test
+	public void tomcatMetrics() throws Exception {
+		AnnotationConfigEmbeddedWebApplicationContext context = new AnnotationConfigEmbeddedWebApplicationContext(
+				Config.class);
+		try {
+			TomcatPublicMetrics tomcatMetrics = context
+					.getBean(TomcatPublicMetrics.class);
+			Iterator<Metric<?>> metrics = tomcatMetrics.metrics().iterator();
+			assertThat(metrics.next().getName(), equalTo("httpsessions.max"));
+			assertThat(metrics.next().getName(), equalTo("httpsessions.active"));
+			assertThat(metrics.hasNext(), equalTo(false));
+		}
+		finally {
+			context.close();
+		}
+	}
+
+	@Configuration
+	static class Config {
+
+		@Bean
+		public TomcatEmbeddedServletContainerFactory containerFactory() {
+			TomcatEmbeddedServletContainerFactory factory = new TomcatEmbeddedServletContainerFactory();
+			factory.setPort(SocketUtils.findAvailableTcpPort(40000));
+			return factory;
+		}
+
+		@Bean
+		public TomcatPublicMetrics metrics() {
+			return new TomcatPublicMetrics();
+		}
+
+	}
+
+}