Align metrics with Spring Boot 1.3

Should be no change for users of Boot 1.2 right now, but with this
patch it is possible to use 1.3 with the new conventions for metrics
(e.g. in particular exporting by declaring beans of type
MetricWriter)

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/eureka/EurekaDiscoveryClientConfiguration.java

@@ -17,6 +17,8 @@
 package org.springframework.cloud.netflix.eureka;
 
 import java.lang.reflect.Field;
+import java.util.Collections;
+import java.util.List;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
 
@@ -26,6 +28,7 @@ import lombok.extern.apachecommons.CommonsLog;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.actuate.endpoint.Endpoint;
+import org.springframework.boot.actuate.metrics.reader.CompositeMetricReader;
 import org.springframework.boot.actuate.metrics.reader.MetricReader;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
@@ -220,11 +223,15 @@ public class EurekaDiscoveryClientConfiguration implements SmartLifecycle, Order
 	@ConditionalOnClass(Endpoint.class)
 	@ConditionalOnBean(MetricReader.class)
 	protected static class EurekaHealthIndicatorConfiguration {
+		
+		@Autowired
+		private List<MetricReader> metricReaders = Collections.emptyList();
+		
 		@Bean
 		@ConditionalOnMissingBean
 		public EurekaHealthIndicator eurekaHealthIndicator(
-				com.netflix.discovery.DiscoveryClient eurekaDiscoveryClient,
-				MetricReader metrics, EurekaInstanceConfig config) {
+				com.netflix.discovery.DiscoveryClient eurekaDiscoveryClient, EurekaInstanceConfig config) {
+			CompositeMetricReader metrics = new CompositeMetricReader(metricReaders.toArray(new MetricReader[0]));
 			return new EurekaHealthIndicator(eurekaDiscoveryClient, metrics, config);
 		}
 	}

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/servo/ServoMetricsAutoConfiguration.java

@@ -18,7 +18,10 @@ package org.springframework.cloud.netflix.servo;
 
 import org.springframework.boot.actuate.autoconfigure.EndpointAutoConfiguration;
 import org.springframework.boot.actuate.autoconfigure.MetricRepositoryAutoConfiguration;
+import org.springframework.boot.actuate.metrics.GaugeService;
+import org.springframework.boot.actuate.metrics.Metric;
 import org.springframework.boot.actuate.metrics.reader.MetricReader;
+import org.springframework.boot.actuate.metrics.writer.Delta;
 import org.springframework.boot.actuate.metrics.writer.MetricWriter;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.AutoConfigureBefore;
@@ -38,7 +41,7 @@ import com.netflix.servo.monitor.Monitors;
  */
 @Configuration
 @ConditionalOnClass({ Monitors.class, MetricReader.class })
-@ConditionalOnBean(MetricReader.class)
+@ConditionalOnBean(GaugeService.class)
 @AutoConfigureBefore(EndpointAutoConfiguration.class)
 @AutoConfigureAfter({ MetricRepositoryAutoConfiguration.class })
 public class ServoMetricsAutoConfiguration {
@@ -51,9 +54,34 @@ public class ServoMetricsAutoConfiguration {
 
 	@Bean
 	@ConditionalOnMissingBean
-	public ServoMetricCollector servoMetricCollector(MetricWriter metrics,
-													 ServoMetricNaming naming) {
-		return new ServoMetricCollector(metrics, naming);
+	public ServoMetricCollector servoMetricCollector(GaugeService gauges,
+			ServoMetricNaming naming) {
+		return new ServoMetricCollector(new ActuatorMetricWriter(gauges), naming);
+	}
+
+	// TODO: refactor this when Spring Boot 1.3 is mandatory
+	private static class ActuatorMetricWriter implements MetricWriter {
+
+		private GaugeService gauges;
+
+		public ActuatorMetricWriter(GaugeService gauges) {
+			this.gauges = gauges;
+		}
+
+		@Override
+		public void increment(Delta<?> delta) {
+		}
+
+		@Override
+		public void set(Metric<?> value) {
+			gauges.submit(value.getName(), value.getValue().doubleValue());
+		}
+
+		@Override
+		public void reset(String metricName) {
+			gauges.submit(metricName, 0.);
+		}
+
 	}
 
 }