Add MetricsEndpointMetricReader for exporting all metrics

User can add a bean of type MetricsEndpointMetricReader to opt in
to exporting all metrics via the MetricsEndpoint (instead of via
MetricReaders). There are disadvantages (like no accurate timestamps)
so it's best to leave it as an opt in.

Also improved tests for metric auto configuration a bit.

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

@@ -22,12 +22,15 @@ import java.util.List;
 import java.util.Map;
 
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.actuate.endpoint.MetricsEndpointMetricReader;
 import org.springframework.boot.actuate.metrics.export.MetricExportProperties;
 import org.springframework.boot.actuate.metrics.export.MetricExporters;
+import org.springframework.boot.actuate.metrics.reader.CompositeMetricReader;
 import org.springframework.boot.actuate.metrics.reader.MetricReader;
 import org.springframework.boot.actuate.metrics.writer.MetricWriter;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.scheduling.annotation.EnableScheduling;
@@ -40,6 +43,7 @@ import org.springframework.scheduling.config.ScheduledTaskRegistrar;
 @Configuration
 @EnableScheduling
 @ConditionalOnProperty(value = "spring.metrics.export.enabled", matchIfMissing = true)
+@EnableConfigurationProperties(MetricExportProperties.class)
 public class MetricExportAutoConfiguration {
 
 	@Autowired(required = false)
@@ -54,28 +58,40 @@ public class MetricExportAutoConfiguration {
 
 	@Autowired(required = false)
 	@ActuatorMetricReader
-	private MetricReader reader;
+	private List<MetricReader> readers;
+
+	@Autowired(required = false)
+	private MetricsEndpointMetricReader endpointReader;
 
 	@Bean
 	@ConditionalOnMissingBean
 	public SchedulingConfigurer metricWritersMetricExporter() {
+
 		Map<String, MetricWriter> writers = new HashMap<String, MetricWriter>();
-		if (this.reader != null) {
+
+		MetricReader reader = endpointReader;
+		if (reader == null && !this.readers.isEmpty()) {
+			reader = new CompositeMetricReader(this.readers.toArray(new MetricReader[0]));
+		}
+
+		if (reader != null) {
 			writers.putAll(this.writers);
 			for (String name : this.writers.keySet()) {
 				if (this.actuatorMetrics.contains(writers.get(name))) {
 					writers.remove(name);
 				}
 			}
-			MetricExporters exporters = new MetricExporters(this.reader, writers,
+			MetricExporters exporters = new MetricExporters(reader, writers, this.metrics);
-					this.metrics);
 			return exporters;
 		}
+
 		return new SchedulingConfigurer() {
 
 			@Override
 			public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
 			}
 		};
+
 	}
+
 }

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

@@ -58,10 +58,20 @@ public class MetricsEndpoint extends AbstractEndpoint<Map<String, Object>> {
 		AnnotationAwareOrderComparator.sort(this.publicMetrics);
 	}
 
+	public void registerPublicMetrics(PublicMetrics metrics) {
+		this.publicMetrics.add(metrics);
+		AnnotationAwareOrderComparator.sort(this.publicMetrics);
+	}
+
+	public void unregisterPublicMetrics(PublicMetrics metrics) {
+		this.publicMetrics.remove(metrics);
+	}
+
 	@Override
 	public Map<String, Object> invoke() {
 		Map<String, Object> result = new LinkedHashMap<String, Object>();
-		for (PublicMetrics publicMetric : this.publicMetrics) {
+		List<PublicMetrics> metrics = new ArrayList<PublicMetrics>(this.publicMetrics);
+		for (PublicMetrics publicMetric : metrics) {
 			try {
 				for (Metric<?> metric : publicMetric.metrics()) {
 					result.put(metric.getName(), metric.getValue());

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

@@ -0,0 +1,71 @@
+/*
+ * 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.endpoint;
+
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import org.springframework.boot.actuate.metrics.Metric;
+import org.springframework.boot.actuate.metrics.reader.MetricReader;
+
+/**
+ * A {@link MetricReader} that pulls all current values out of the {@link MetricsEndpoint}
+ * . No timestamp information is available, so there is no way to check if the values are
+ * recent, and they all come out with the default (current time).
+ * 
+ * @author Dave Syer
+ *
+ */
+public class MetricsEndpointMetricReader implements MetricReader {
+
+	private final MetricsEndpoint endpoint;
+
+	public MetricsEndpointMetricReader(MetricsEndpoint endpoint) {
+		this.endpoint = endpoint;
+	}
+
+	@Override
+	public Metric<?> findOne(String metricName) {
+		Metric<Number> metric = null;
+		Object value = endpoint.invoke().get(metricName);
+		if (value != null) {
+			metric = new Metric<Number>(metricName, (Number) value);
+		}
+		return metric;
+	}
+
+	@Override
+	public Iterable<Metric<?>> findAll() {
+		List<Metric<?>> metrics = new ArrayList<Metric<?>>();
+		Map<String, Object> values = endpoint.invoke();
+		Date timestamp = new Date();
+		for (Entry<String, Object> entry : values.entrySet()) {
+			String name = entry.getKey();
+			Object value = entry.getValue();
+			metrics.add(new Metric<Number>(name, (Number) value, timestamp));
+		}
+		return metrics;
+	}
+
+	@Override
+	public long count() {
+		return endpoint.invoke().size();
+	}
+
+}

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

@@ -0,0 +1,135 @@
+/*
+ * 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.autoconfigure;
+
+import static org.junit.Assert.assertNotNull;
+
+import org.junit.After;
+import org.junit.Test;
+import org.mockito.Matchers;
+import org.mockito.Mockito;
+import org.springframework.boot.actuate.endpoint.MetricsEndpointMetricReader;
+import org.springframework.boot.actuate.metrics.GaugeService;
+import org.springframework.boot.actuate.metrics.Metric;
+import org.springframework.boot.actuate.metrics.export.MetricCopyExporter;
+import org.springframework.boot.actuate.metrics.export.MetricExporters;
+import org.springframework.boot.actuate.metrics.writer.MetricWriter;
+import org.springframework.boot.autoconfigure.PropertyPlaceholderAutoConfiguration;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.integration.channel.FixedSubscriberChannel;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.MessageHandler;
+import org.springframework.messaging.MessagingException;
+import org.springframework.messaging.SubscribableChannel;
+
+/**
+ * Tests for {@link MetricRepositoryAutoConfiguration}.
+ *
+ * @author Phillip Webb
+ * @author Dave Syer
+ */
+public class MetricExportAutoConfigurationTests {
+
+	private AnnotationConfigApplicationContext context;
+
+	@After
+	public void after() {
+		if (this.context != null) {
+			this.context.close();
+		}
+	}
+
+	@Test
+	public void defaultExporterWhenMessageChannelAvailable() throws Exception {
+		this.context = new AnnotationConfigApplicationContext(
+				MessageChannelConfiguration.class,
+				MetricRepositoryAutoConfiguration.class,
+				MetricsChannelAutoConfiguration.class,
+				MetricExportAutoConfiguration.class,
+				PropertyPlaceholderAutoConfiguration.class);
+		MetricExporters exporter = this.context.getBean(MetricExporters.class);
+		assertNotNull(exporter);
+	}
+
+	@Test
+	public void provideAdditionalWriter() {
+		this.context = new AnnotationConfigApplicationContext(WriterConfig.class,
+				MetricRepositoryAutoConfiguration.class,
+				MetricExportAutoConfiguration.class,
+				PropertyPlaceholderAutoConfiguration.class);
+		GaugeService gaugeService = this.context.getBean(GaugeService.class);
+		assertNotNull(gaugeService);
+		gaugeService.submit("foo", 2.7);
+		MetricExporters exporters = this.context.getBean(MetricExporters.class);
+		MetricCopyExporter exporter = (MetricCopyExporter) exporters.getExporters().get(
+				"writer");
+		exporter.setIgnoreTimestamps(true);
+		exporter.export();
+		MetricWriter writer = this.context.getBean("writer", MetricWriter.class);
+		Mockito.verify(writer, Mockito.atLeastOnce()).set(Matchers.any(Metric.class));
+	}
+
+	@Test
+	public void exportMetricsEndpoint() {
+		this.context = new AnnotationConfigApplicationContext(WriterConfig.class,
+				MetricEndpointConfiguration.class,
+				MetricExportAutoConfiguration.class,
+				PropertyPlaceholderAutoConfiguration.class);
+		MetricExporters exporters = this.context.getBean(MetricExporters.class);
+		MetricCopyExporter exporter = (MetricCopyExporter) exporters.getExporters().get(
+				"writer");
+		exporter.setIgnoreTimestamps(true);
+		exporter.export();
+		MetricsEndpointMetricReader reader = this.context.getBean("endpointReader", MetricsEndpointMetricReader.class);
+		Mockito.verify(reader, Mockito.atLeastOnce()).findAll();
+	}
+
+	@Configuration
+	public static class MessageChannelConfiguration {
+		@Bean
+		public SubscribableChannel metricsChannel() {
+			return new FixedSubscriberChannel(new MessageHandler() {
+				@Override
+				public void handleMessage(Message<?> message) throws MessagingException {
+				}
+			});
+		}
+	}
+
+	@Configuration
+	public static class WriterConfig {
+
+		@Bean
+		public MetricWriter writer() {
+			return Mockito.mock(MetricWriter.class);
+		}
+
+	}
+
+	@Configuration
+	public static class MetricEndpointConfiguration {
+
+		@Bean
+		public MetricsEndpointMetricReader endpointReader() {
+			return Mockito.mock(MetricsEndpointMetricReader.class);
+		}
+
+	}
+
+}

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

@@ -16,41 +16,29 @@
 
 package org.springframework.boot.actuate.autoconfigure;
 
+import static org.hamcrest.Matchers.equalTo;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertThat;
+import static org.mockito.Mockito.mock;
+
 import org.junit.After;
 import org.junit.Test;
-import org.mockito.Matchers;
-import org.mockito.Mockito;
 import org.springframework.boot.actuate.metrics.CounterService;
 import org.springframework.boot.actuate.metrics.GaugeService;
-import org.springframework.boot.actuate.metrics.Metric;
 import org.springframework.boot.actuate.metrics.buffer.BufferCounterService;
 import org.springframework.boot.actuate.metrics.buffer.BufferGaugeService;
 import org.springframework.boot.actuate.metrics.dropwizard.DropwizardMetricServices;
-import org.springframework.boot.actuate.metrics.export.MetricCopyExporter;
-import org.springframework.boot.actuate.metrics.export.MetricExporters;
 import org.springframework.boot.actuate.metrics.reader.MetricReader;
 import org.springframework.boot.actuate.metrics.reader.PrefixMetricReader;
-import org.springframework.boot.actuate.metrics.writer.MetricWriter;
-import org.springframework.boot.autoconfigure.PropertyPlaceholderAutoConfiguration;
 import org.springframework.boot.autoconfigure.aop.AopAutoConfiguration;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.integration.channel.FixedSubscriberChannel;
-import org.springframework.messaging.Message;
-import org.springframework.messaging.MessageHandler;
-import org.springframework.messaging.MessagingException;
-import org.springframework.messaging.SubscribableChannel;
 
 import com.codahale.metrics.Gauge;
 import com.codahale.metrics.MetricRegistry;
 
-import static org.hamcrest.Matchers.equalTo;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertThat;
-import static org.mockito.Mockito.mock;
-
 /**
  * Tests for {@link MetricRepositoryAutoConfiguration}.
  *
@@ -81,36 +69,6 @@ public class MetricRepositoryAutoConfigurationTests {
 				.getValue());
 	}
 
-	@Test
-	public void defaultExporterWhenMessageChannelAvailable() throws Exception {
-		this.context = new AnnotationConfigApplicationContext(
-				MessageChannelConfiguration.class,
-				MetricRepositoryAutoConfiguration.class,
-				MetricsChannelAutoConfiguration.class,
-				MetricExportAutoConfiguration.class,
-				PropertyPlaceholderAutoConfiguration.class);
-		MetricExporters exporter = this.context.getBean(MetricExporters.class);
-		assertNotNull(exporter);
-	}
-
-	@Test
-	public void provideAdditionalWriter() {
-		this.context = new AnnotationConfigApplicationContext(WriterConfig.class,
-				MetricRepositoryAutoConfiguration.class,
-				MetricExportAutoConfiguration.class,
-				PropertyPlaceholderAutoConfiguration.class);
-		GaugeService gaugeService = this.context.getBean(GaugeService.class);
-		assertNotNull(gaugeService);
-		gaugeService.submit("foo", 2.7);
-		MetricExporters exporters = this.context.getBean(MetricExporters.class);
-		MetricCopyExporter exporter = (MetricCopyExporter) exporters.getExporters().get(
-				"writer");
-		exporter.setIgnoreTimestamps(true);
-		exporter.export();
-		MetricWriter writer = this.context.getBean("writer", MetricWriter.class);
-		Mockito.verify(writer, Mockito.atLeastOnce()).set(Matchers.any(Metric.class));
-	}
-
 	@Test
 	public void dropwizardInstalledIfPresent() {
 		this.context = new AnnotationConfigApplicationContext(
@@ -138,28 +96,6 @@ public class MetricRepositoryAutoConfigurationTests {
 				equalTo(0));
 	}
 
-	@Configuration
-	public static class MessageChannelConfiguration {
-		@Bean
-		public SubscribableChannel metricsChannel() {
-			return new FixedSubscriberChannel(new MessageHandler() {
-				@Override
-				public void handleMessage(Message<?> message) throws MessagingException {
-				}
-			});
-		}
-	}
-
-	@Configuration
-	public static class WriterConfig {
-
-		@Bean
-		public MetricWriter writer() {
-			return Mockito.mock(MetricWriter.class);
-		}
-
-	}
-
 	@Configuration
 	public static class Config {