Add support for Statsd metric export

spring-boot-actuator/pom.xml

 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 	<modelVersion>4.0.0</modelVersion>
 	<parent>
 		<groupId>org.springframework.boot</groupId>
@@ -62,6 +63,11 @@
 			<artifactId>javax.mail</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>com.timgroup</groupId>
+			<artifactId>java-statsd-client</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>io.dropwizard.metrics</groupId>
 			<artifactId>metrics-core</artifactId>

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/statsd/StatsdMetricWriter.java

+/*
+ * Copyright 2012-2015 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.metrics.statsd;
+
+import java.io.Closeable;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.springframework.boot.actuate.metrics.Metric;
+import org.springframework.boot.actuate.metrics.writer.Delta;
+import org.springframework.boot.actuate.metrics.writer.MetricWriter;
+import org.springframework.util.StringUtils;
+
+import com.timgroup.statsd.NonBlockingStatsDClient;
+import com.timgroup.statsd.StatsDClientErrorHandler;
+
+/**
+ * A {@link MetricWriter} that pushes data to statsd. Statsd has the concept of counters
+ * and gauges, but only supports gauges with data type Long, so values will be truncated
+ * towards zero. Metrics whose name contains "timer." (but not "gauge." or "counter.")
+ * will be treated as execution times (in statsd terms). Anything incremented is treated
+ * as a counter, and anything with a snapshot value in {@link #set(Metric)} is treated as
+ * a gauge.
+ *
+ * @author Dave Syer
+ */
+public class StatsdMetricWriter implements MetricWriter, Closeable {
+
+	private static Log logger = LogFactory.getLog(StatsdMetricWriter.class);
+
+	private final NonBlockingStatsDClient client;
+
+	/**
+	 * Create a new writer with the given parameters.
+	 *
+	 * @param host the hostname for the statsd server
+	 * @param port the port for the statsd server
+	 */
+	public StatsdMetricWriter(String host, int port) {
+		this(null, host, port);
+	}
+
+	/**
+	 * Create a new writer with the given parameters.
+	 *
+	 * @param prefix the prefix to apply to all metric names (can be null)
+	 * @param host the hostname for the statsd server
+	 * @param port the port for the statsd server
+	 */
+	public StatsdMetricWriter(String prefix, String host, int port) {
+		prefix = StringUtils.hasText(prefix) ? prefix : null;
+		while (prefix != null && prefix.endsWith(".")) {
+			prefix = prefix.substring(0, prefix.length() - 1);
+		}
+		this.client = new NonBlockingStatsDClient(prefix, host, port,
+				new LoggingStatsdErrorHandler());
+	}
+
+	@Override
+	public void increment(Delta<?> delta) {
+		this.client.count(delta.getName(), delta.getValue().longValue());
+	}
+
+	@Override
+	public void set(Metric<?> value) {
+		String name = value.getName();
+		if (name.contains("timer.") && !name.contains("gauge.")
+				&& !name.contains("counter.")) {
+			this.client.recordExecutionTime(name, value.getValue().longValue());
+		}
+		else {
+			this.client.gauge(name, value.getValue().longValue());
+		}
+	}
+
+	@Override
+	public void reset(String name) {
+		if (name.contains("counter.")) {
+			this.client.gauge(name, 0L);
+		}
+	}
+
+	@Override
+	public void close() {
+		this.client.stop();
+	}
+
+	private static final class LoggingStatsdErrorHandler implements
+			StatsDClientErrorHandler {
+		@Override
+		public void handle(Exception e) {
+			logger.debug("Failed to write metric. Exception: " + e.getClass()
+					+ ", message: " + e.getMessage());
+		}
+	}
+
+}

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/statsd/package-info.java

+/*
+ * Copyright 2012-2015 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.
+ */
+
+/**
+ * Metrics integration with Statsd.
+ */
+package org.springframework.boot.actuate.metrics.statsd;
+

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/statsd/StatsdMetricWriterTests.java

+/*
+ * Copyright 2012-2015 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.metrics.statsd;
+
+import java.net.DatagramPacket;
+import java.net.DatagramSocket;
+import java.net.SocketException;
+import java.nio.charset.Charset;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.junit.After;
+import org.junit.Test;
+import org.springframework.boot.actuate.metrics.Metric;
+import org.springframework.boot.actuate.metrics.writer.Delta;
+import org.springframework.util.SocketUtils;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Tests for {@link StatsdMetricWriter}.
+ *
+ * @author Dave Syer
+ */
+public class StatsdMetricWriterTests {
+
+	private int port = SocketUtils.findAvailableTcpPort();
+
+	private DummyStatsDServer server = new DummyStatsDServer(this.port);
+
+	private StatsdMetricWriter writer = new StatsdMetricWriter("me", "localhost",
+			this.port);
+
+	@After
+	public void close() {
+		this.server.stop();
+		this.writer.close();
+	}
+
+	@Test
+	public void increment() {
+		this.writer.increment(new Delta<Long>("counter.foo", 3L));
+		this.server.waitForMessage();
+		assertEquals("me.counter.foo:3|c", this.server.messagesReceived().get(0));
+	}
+
+	@Test
+	public void setLongMetric() throws Exception {
+		this.writer.set(new Metric<Long>("gauge.foo", 3L));
+		this.server.waitForMessage();
+		assertEquals("me.gauge.foo:3|g", this.server.messagesReceived().get(0));
+	}
+
+	@Test
+	public void setDoubleMetric() throws Exception {
+		this.writer.set(new Metric<Double>("gauge.foo", 3.7));
+		this.server.waitForMessage();
+		// Doubles are truncated
+		assertEquals("me.gauge.foo:3|g", this.server.messagesReceived().get(0));
+	}
+
+	@Test
+	public void setTimerMetric() throws Exception {
+		this.writer.set(new Metric<Long>("timer.foo", 37L));
+		this.server.waitForMessage();
+		assertEquals("me.timer.foo:37|ms", this.server.messagesReceived().get(0));
+	}
+
+	@Test
+	public void nullPrefix() throws Exception {
+		this.writer = new StatsdMetricWriter("localhost", this.port);
+		this.writer.set(new Metric<Long>("gauge.foo", 3L));
+		this.server.waitForMessage();
+		assertEquals("gauge.foo:3|g", this.server.messagesReceived().get(0));
+	}
+
+	@Test
+	public void perioPrefix() throws Exception {
+		this.writer = new StatsdMetricWriter("my.", "localhost", this.port);
+		this.writer.set(new Metric<Long>("gauge.foo", 3L));
+		this.server.waitForMessage();
+		assertEquals("my.gauge.foo:3|g", this.server.messagesReceived().get(0));
+	}
+
+	private static final class DummyStatsDServer {
+
+		private final List<String> messagesReceived = new ArrayList<String>();
+		private final DatagramSocket server;
+
+		public DummyStatsDServer(int port) {
+			try {
+				this.server = new DatagramSocket(port);
+			}
+			catch (SocketException e) {
+				throw new IllegalStateException(e);
+			}
+			new Thread(new Runnable() {
+				@Override
+				public void run() {
+					try {
+						final DatagramPacket packet = new DatagramPacket(new byte[256],
+								256);
+						DummyStatsDServer.this.server.receive(packet);
+						DummyStatsDServer.this.messagesReceived.add(new String(packet
+								.getData(), Charset.forName("UTF-8")).trim());
+					}
+					catch (Exception e) {
+					}
+				}
+			}).start();
+		}
+
+		public void stop() {
+			this.server.close();
+		}
+
+		public void waitForMessage() {
+			while (this.messagesReceived.isEmpty()) {
+				try {
+					Thread.sleep(50L);
+				}
+				catch (InterruptedException e) {
+				}
+			}
+		}
+
+		public List<String> messagesReceived() {
+			return new ArrayList<String>(this.messagesReceived);
+		}
+	}
+}

spring-boot-dependencies/pom.xml

@@ -136,6 +136,7 @@
 		<spring-social-linkedin.version>1.0.1.RELEASE</spring-social-linkedin.version>
 		<spring-social-twitter.version>1.1.0.RELEASE</spring-social-twitter.version>
 		<spring-ws.version>2.2.1.RELEASE</spring-ws.version>
+		<statsd-client.version>3.0.1</statsd-client.version>
 		<sun-mail.version>${javax-mail.version}</sun-mail.version>
 		<thymeleaf.version>2.1.4.RELEASE</thymeleaf.version>
 		<thymeleaf-extras-springsecurity4.version>2.1.2.RELEASE</thymeleaf-extras-springsecurity4.version>
@@ -552,6 +553,11 @@
 				<artifactId>javax.mail</artifactId>
 				<version>${sun-mail.version}</version>
 			</dependency>
+			<dependency>
+				<groupId>com.timgroup</groupId>
+				<artifactId>java-statsd-client</artifactId>
+				<version>${statsd-client.version}</version>
+			</dependency>
 			<dependency>
 				<groupId>com.zaxxer</groupId>
 				<artifactId>HikariCP</artifactId>

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

@@ -957,6 +957,51 @@ MetricWriter metricWriter() {
 
 
 
+[[production-ready-metric-writers-export-to-statsd]]
+==== Example: Export to Statsd
+If you provide a `@Bean` of type `StatsdMetricWriter`  the metrics are exported to a
+statsd server:
+
+[source,java,indent=0]
+----
+@Value("${spring.application.name:application}.${random.value:0000}")
+private String prefix = "metrics";
+
+@Value("${statsd.host:localhost}")
+private String host = "localhost";
+
+@Value("${statsd.port:8125}")
+private int port;
+
+@Bean
+MetricWriter metricWriter() {
+  return new StatsdMetricWriter(prefix, host, port);
+}
+----
+
+
+[[production-ready-metric-writers-export-to-jmx]]
+==== Example: Export to JMX
+If you provide a `@Bean` of type `JmxMetricWriter` the metrics are exported as MBeans to
+the local server (the `MBeanExporter` is provided by Spring Boot JMX autoconfiguration as
+long as it is switched on). Metrics can then be inspected, graphed, alerted etc. using any
+tool that understands JMX (e.g. JConsole or JVisualVM). Example:
+
+[source,java,indent=0]
+----
+@Bean
+MetricWriter metricWriter(MBeanExporter exporter) {
+  return new JmxMetricWriter(exporter);
+}
+----
+
+Each metric is exported as an individual MBean. The format for the `ObjectNames` is given
+by an `ObjectNamingStrategy` which can be injected into the `JmxMetricWriter` (the default
+breaks up the metric name and tags the first two period-separated sections in a way that
+should make the metrics group nicely in JVisualVM or JConsole).
+
+
+
 [[production-ready-metric-aggregation]]
 === Aggregating metrics from multiple sources
 There is an `AggregateMetricReader` that you can use to consolidate metrics from different