Refactor PublicMetrics registration

Rework flexible PublicMetrics registration introduced in 2be6b3e4 to
restore compatibility with v1.1 VanillaPublicMetrics. The new
MetricReaderPublicMetrics class now exposes metrics from a MetricReader
and VanillaPublicMetrics is deprecated. The MetricsEndpoint can now
exposes a collection of PublicMetric interface directly.

See gh-1094

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

@@ -16,9 +16,11 @@
 
 package org.springframework.boot.actuate.autoconfigure;
 
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.Properties;
 
@@ -32,13 +34,13 @@ import org.springframework.boot.actuate.endpoint.Endpoint;
 import org.springframework.boot.actuate.endpoint.EnvironmentEndpoint;
 import org.springframework.boot.actuate.endpoint.HealthEndpoint;
 import org.springframework.boot.actuate.endpoint.InfoEndpoint;
+import org.springframework.boot.actuate.endpoint.MetricReaderPublicMetrics;
 import org.springframework.boot.actuate.endpoint.MetricsEndpoint;
 import org.springframework.boot.actuate.endpoint.PublicMetrics;
 import org.springframework.boot.actuate.endpoint.RequestMappingEndpoint;
 import org.springframework.boot.actuate.endpoint.ShutdownEndpoint;
 import org.springframework.boot.actuate.endpoint.SystemPublicMetrics;
 import org.springframework.boot.actuate.endpoint.TraceEndpoint;
-import org.springframework.boot.actuate.endpoint.VanillaPublicMetrics;
 import org.springframework.boot.actuate.health.HealthAggregator;
 import org.springframework.boot.actuate.health.HealthIndicator;
 import org.springframework.boot.actuate.health.OrderedHealthAggregator;
@@ -85,10 +87,10 @@ public class EndpointAutoConfiguration {
 	Map<String, HealthIndicator> healthIndicators = new HashMap<String, HealthIndicator>();
 
 	@Autowired(required = false)
-	private MetricReader metricRepository = new InMemoryMetricRepository();
+	private MetricReader metricReader = new InMemoryMetricRepository();
 
 	@Autowired(required = false)
-	private Collection<PublicMetrics> allMetrics;
+	private Collection<PublicMetrics> publicMetrics;
 
 	@Autowired(required = false)
 	private TraceRepository traceRepository = new InMemoryTraceRepository();
@@ -129,8 +131,13 @@ public class EndpointAutoConfiguration {
 	@Bean
 	@ConditionalOnMissingBean
 	public MetricsEndpoint metricsEndpoint() {
-		PublicMetrics metrics = new VanillaPublicMetrics(this.metricRepository, this.allMetrics);
+		List<PublicMetrics> publicMetrics = new ArrayList<PublicMetrics>();
-		return new MetricsEndpoint(metrics);
+		publicMetrics.add(new SystemPublicMetrics());
+		publicMetrics.add(new MetricReaderPublicMetrics(this.metricReader));
+		if (this.publicMetrics != null) {
+			publicMetrics.addAll(this.publicMetrics);
+		}
+		return new MetricsEndpoint(publicMetrics);
 	}
 
 	@Bean
@@ -158,19 +165,6 @@ public class EndpointAutoConfiguration {
 		return new ShutdownEndpoint();
 	}
 
-	@Configuration
-	@ConditionalOnClass(AbstractHandlerMethodMapping.class)
-	protected static class RequestMappingEndpointConfiguration {
-
-		@Bean
-		@ConditionalOnMissingBean
-		public RequestMappingEndpoint requestMappingEndpoint() {
-			RequestMappingEndpoint endpoint = new RequestMappingEndpoint();
-			return endpoint;
-		}
-
-	}
-
 	@Bean
 	@ConditionalOnMissingBean
 	public ConfigurationPropertiesReportEndpoint configurationPropertiesReportEndpoint() {
@@ -180,11 +174,14 @@ public class EndpointAutoConfiguration {
 	}
 
 	@Configuration
-	protected static class CorePublicMetrics {
+	@ConditionalOnClass(AbstractHandlerMethodMapping.class)
+	protected static class RequestMappingEndpointConfiguration {
 
 		@Bean
-		SystemPublicMetrics systemPublicMetrics() {
+		@ConditionalOnMissingBean
-			return new SystemPublicMetrics();
+		public RequestMappingEndpoint requestMappingEndpoint() {
+			RequestMappingEndpoint endpoint = new RequestMappingEndpoint();
+			return endpoint;
 		}
 
 	}

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

@@ -0,0 +1,53 @@
+/*
+ * 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.List;
+
+import org.springframework.boot.actuate.metrics.Metric;
+import org.springframework.boot.actuate.metrics.reader.MetricReader;
+import org.springframework.util.Assert;
+
+/**
+ * {@link PublicMetrics} exposed from a {@link MetricReader}.
+ *
+ * @author Dave Syer
+ * @author Christian Dupuis
+ * @author Stephane Nicoll
+ * @author Phillip Webb
+ */
+public class MetricReaderPublicMetrics implements PublicMetrics {
+
+	private final MetricReader metricReader;
+
+	public MetricReaderPublicMetrics(MetricReader metricReader) {
+		Assert.notNull(metricReader, "MetricReader must not be null");
+		this.metricReader = metricReader;
+	}
+
+	@Override
+	public Collection<Metric<?>> metrics() {
+		List<Metric<?>> result = new ArrayList<Metric<?>>();
+		for (Metric<?> metric : this.metricReader.findAll()) {
+			result.add(metric);
+		}
+		return result;
+	}
+
+}

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

@@ -16,40 +16,56 @@
 
 package org.springframework.boot.actuate.endpoint;
 
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
 import java.util.LinkedHashMap;
+import java.util.List;
 import java.util.Map;
 
 import org.springframework.boot.actuate.metrics.Metric;
 import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.core.annotation.AnnotationAwareOrderComparator;
 import org.springframework.util.Assert;
 
 /**
- * {@link Endpoint} to expose {@link PublicMetrics}.
+ * {@link Endpoint} to expose a collection of {@link PublicMetrics}.
  *
  * @author Dave Syer
  */
 @ConfigurationProperties(prefix = "endpoints.metrics", ignoreUnknownFields = false)
 public class MetricsEndpoint extends AbstractEndpoint<Map<String, Object>> {
 
-	private final PublicMetrics metrics;
+	private final List<PublicMetrics> publicMetrics;
 
 	/**
 	 * Create a new {@link MetricsEndpoint} instance.
-	 *
+	 * @param publicMetrics the metrics to expose
-	 * @param metrics the metrics to expose
 	 */
-	public MetricsEndpoint(PublicMetrics metrics) {
+	public MetricsEndpoint(PublicMetrics publicMetrics) {
+		this(Collections.singleton(publicMetrics));
+	}
+
+	/**
+	 * Create a new {@link MetricsEndpoint} instance.
+	 * @param publicMetrics the metrics to expose. The collection will be sorted using the
+	 * {@link AnnotationAwareOrderComparator}.
+	 */
+	public MetricsEndpoint(Collection<PublicMetrics> publicMetrics) {
 		super("metrics");
-		Assert.notNull(metrics, "Metrics must not be null");
+		Assert.notNull(publicMetrics, "PublicMetrics must not be null");
-		this.metrics = metrics;
+		this.publicMetrics = new ArrayList<PublicMetrics>(publicMetrics);
+		AnnotationAwareOrderComparator.sort(this.publicMetrics);
 	}
 
 	@Override
 	public Map<String, Object> invoke() {
 		Map<String, Object> result = new LinkedHashMap<String, Object>();
-		for (Metric<?> metric : this.metrics.metrics()) {
+		for (PublicMetrics publicMetric : this.publicMetrics) {
+			for (Metric<?> metric : publicMetric.metrics()) {
 				result.put(metric.getName(), metric.getValue());
 			}
+		}
 		return result;
 	}
 

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

@@ -26,6 +26,7 @@ import java.util.LinkedHashSet;
 import java.util.List;
 
 import org.springframework.boot.actuate.metrics.Metric;
+import org.springframework.core.Ordered;
 import org.springframework.util.StringUtils;
 
 /**
@@ -36,7 +37,7 @@ import org.springframework.util.StringUtils;
  * @author Stephane Nicoll
  * @since 1.2.0
  */
-public class SystemPublicMetrics implements PublicMetrics {
+public class SystemPublicMetrics implements PublicMetrics, Ordered {
 
 	private long timestamp;
 
@@ -44,16 +45,19 @@ public class SystemPublicMetrics implements PublicMetrics {
 		this.timestamp = System.currentTimeMillis();
 	}
 
+	@Override
+	public int getOrder() {
+		return Ordered.HIGHEST_PRECEDENCE + 10;
+	}
+
 	@Override
 	public Collection<Metric<?>> metrics() {
 		Collection<Metric<?>> result = new LinkedHashSet<Metric<?>>();
-
 		addBasicMetrics(result);
 		addHeapMetrics(result);
 		addThreadMetrics(result);
 		addClassLoadingMetrics(result);
 		addGarbageCollectionMetrics(result);
-
 		return result;
 	}
 

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

@@ -17,7 +17,6 @@
 package org.springframework.boot.actuate.endpoint;
 
 import java.util.Collection;
-import java.util.Collections;
 import java.util.LinkedHashSet;
 
 import org.springframework.boot.actuate.metrics.Metric;
@@ -26,27 +25,21 @@ import org.springframework.util.Assert;
 
 /**
  * Default implementation of {@link PublicMetrics} that exposes all metrics from a
- * {@link MetricReader} along with a collection of configurable {@link PublicMetrics}
+ * {@link MetricReader} along with memory information.
- * instances.
  *
  * @author Dave Syer
  * @author Christian Dupuis
- * @author Stephane Nicoll
+ * @deprecated since 1.2 in favor of {@link SystemPublicMetrics},
+ * {@code MetricReaderPublicMetrics}
  */
-public class VanillaPublicMetrics implements PublicMetrics {
+@Deprecated
+public class VanillaPublicMetrics extends SystemPublicMetrics {
 
 	private final MetricReader reader;
-	private final Collection<PublicMetrics> publicMetrics;
-
-	public VanillaPublicMetrics(MetricReader reader, Collection<PublicMetrics> publicMetrics) {
-		Assert.notNull(reader, "MetricReader must not be null");
-		Assert.notNull(publicMetrics, "PublicMetrics must not be null");
-		this.reader = reader;
-		this.publicMetrics = publicMetrics;
-	}
 
 	public VanillaPublicMetrics(MetricReader reader) {
-		this(reader, Collections.<PublicMetrics>emptyList());
+		Assert.notNull(reader, "MetricReader must not be null");
+		this.reader = reader;
 	}
 
 	@Override
@@ -55,10 +48,7 @@ public class VanillaPublicMetrics implements PublicMetrics {
 		for (Metric<?> metric : this.reader.findAll()) {
 			result.add(metric);
 		}
-		for (PublicMetrics publicMetric : publicMetrics) {
+		result.addAll(super.metrics());
-			result.addAll(publicMetric.metrics());
-		}
-
 		return result;
 	}
 

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

@@ -16,6 +16,10 @@
 
 package org.springframework.boot.actuate.autoconfigure;
 
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Map;
+
 import org.junit.After;
 import org.junit.Test;
 import org.springframework.boot.actuate.endpoint.AutoConfigurationReportEndpoint;
@@ -43,10 +47,6 @@ import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 
-import java.util.Collection;
-import java.util.Collections;
-import java.util.Map;
-
 /**
  * Tests for {@link EndpointAutoConfiguration}.
  *
@@ -83,8 +83,8 @@ public class EndpointAutoConfigurationTests {
 
 	@Test
 	public void healthEndpoint() {
-		load(EmbeddedDataSourceConfiguration.class,
+		load(EmbeddedDataSourceConfiguration.class, EndpointAutoConfiguration.class,
-				EndpointAutoConfiguration.class, HealthIndicatorAutoConfiguration.class);
+				HealthIndicatorAutoConfiguration.class);
 		HealthEndpoint bean = this.context.getBean(HealthEndpoint.class);
 		assertNotNull(bean);
 		Health result = bean.invoke();
@@ -94,8 +94,7 @@ public class EndpointAutoConfigurationTests {
 
 	@Test
 	public void healthEndpointWithDefaultHealthIndicator() {
-		load(EndpointAutoConfiguration.class,
+		load(EndpointAutoConfiguration.class, HealthIndicatorAutoConfiguration.class);
-				HealthIndicatorAutoConfiguration.class);
 		HealthEndpoint bean = this.context.getBean(HealthEndpoint.class);
 		assertNotNull(bean);
 		Health result = bean.invoke();
@@ -128,8 +127,7 @@ public class EndpointAutoConfigurationTests {
 
 	@Test
 	public void autoConfigurationAuditEndpoints() {
-		load(EndpointAutoConfiguration.class,
+		load(EndpointAutoConfiguration.class, ConditionEvaluationReport.class);
-				ConditionEvaluationReport.class);
 		assertNotNull(this.context.getBean(AutoConfigurationReportEndpoint.class));
 	}
 
@@ -163,7 +161,6 @@ public class EndpointAutoConfigurationTests {
 		this.context.refresh();
 	}
 
-
 	@Configuration
 	static class CustomPublicMetricsConfig {
 
@@ -172,9 +169,11 @@ public class EndpointAutoConfigurationTests {
 			return new PublicMetrics() {
 				@Override
 				public Collection<Metric<?>> metrics() {
-					return Collections.<Metric<?>>singleton(new Metric<Integer>("foo", 1));
+					Metric<Integer> metric = new Metric<Integer>("foo", 1);
+					return Collections.<Metric<?>> singleton(metric);
 				}
 			};
 		}
+
 	}
 }

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

@@ -0,0 +1,48 @@
+/*
+ * 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.List;
+
+import org.junit.Test;
+import org.springframework.boot.actuate.metrics.Metric;
+import org.springframework.boot.actuate.metrics.reader.MetricReader;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Tests for {@link MetricReaderPublicMetrics}.
+ *
+ * @author Phillip Webb
+ */
+public class MetricReaderPublicMetricsTests {
+
+	@Test
+	public void exposesMetrics() {
+		List<Metric<?>> metrics = new ArrayList<Metric<?>>();
+		metrics.add(mock(Metric.class));
+		metrics.add(mock(Metric.class));
+		MetricReader reader = mock(MetricReader.class);
+		given(reader.findAll()).willReturn(metrics);
+		MetricReaderPublicMetrics publicMetrics = new MetricReaderPublicMetrics(reader);
+		assertEquals(metrics, publicMetrics.metrics());
+	}
+
+}

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

@@ -16,16 +16,25 @@
 
 package org.springframework.boot.actuate.endpoint;
 
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
 
 import org.junit.Test;
 import org.springframework.boot.actuate.metrics.Metric;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.core.Ordered;
 
 import static org.hamcrest.Matchers.equalTo;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertThat;
 
 /**
@@ -35,6 +44,12 @@ import static org.junit.Assert.assertThat;
  */
 public class MetricsEndpointTests extends AbstractEndpointTests<MetricsEndpoint> {
 
+	private Metric<Number> metric1 = new Metric<Number>("a", 1);
+
+	private Metric<Number> metric2 = new Metric<Number>("b", 2);;
+
+	private Metric<Number> metric3 = new Metric<Number>("c", 3);;
+
 	public MetricsEndpointTests() {
 		super(Config.class, MetricsEndpoint.class, "metrics", true, "endpoints.metrics");
 	}
@@ -44,6 +59,43 @@ public class MetricsEndpointTests extends AbstractEndpointTests<MetricsEndpoint>
 		assertThat(getEndpointBean().invoke().get("a"), equalTo((Object) 0.5f));
 	}
 
+	@Test
+	public void ordered() {
+		List<PublicMetrics> publicMetrics = new ArrayList<PublicMetrics>();
+		publicMetrics.add(new TestPublicMetrics(2, this.metric2, this.metric2,
+				this.metric3));
+		publicMetrics.add(new TestPublicMetrics(1, this.metric1));
+		Map<String, Object> metrics = new MetricsEndpoint(publicMetrics).invoke();
+		Iterator<Entry<String, Object>> iterator = metrics.entrySet().iterator();
+		assertEquals("a", iterator.next().getKey());
+		assertEquals("b", iterator.next().getKey());
+		assertEquals("c", iterator.next().getKey());
+		assertFalse(iterator.hasNext());
+	}
+
+	private static class TestPublicMetrics implements PublicMetrics, Ordered {
+
+		private final int order;
+
+		private final List<Metric<?>> metrics;
+
+		public TestPublicMetrics(int order, Metric<?>... metrics) {
+			this.order = order;
+			this.metrics = Arrays.asList(metrics);
+		}
+
+		@Override
+		public int getOrder() {
+			return this.order;
+		}
+
+		@Override
+		public Collection<Metric<?>> metrics() {
+			return this.metrics;
+		}
+
+	}
+
 	@Configuration
 	@EnableConfigurationProperties
 	public static class Config {

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

@@ -16,15 +16,14 @@
 
 package org.springframework.boot.actuate.endpoint;
 
-import static org.junit.Assert.*;
-
 import java.util.HashMap;
 import java.util.Map;
 
 import org.junit.Test;
-
 import org.springframework.boot.actuate.metrics.Metric;
 
+import static org.junit.Assert.assertTrue;
+
 /**
  * Tests for {@link SystemPublicMetrics}
  *

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

@@ -16,12 +16,8 @@
 
 package org.springframework.boot.actuate.endpoint;
 
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
 import java.util.Date;
 import java.util.HashMap;
-import java.util.LinkedHashSet;
 import java.util.Map;
 
 import org.junit.Test;
@@ -29,15 +25,16 @@ import org.springframework.boot.actuate.metrics.Metric;
 import org.springframework.boot.actuate.metrics.repository.InMemoryMetricRepository;
 
 import static org.hamcrest.Matchers.equalTo;
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
 
 /**
  * Tests for {@link VanillaPublicMetrics}.
  *
  * @author Phillip Webb
  * @author Christian Dupuis
- * @author Stephane Nicoll
  */
+@Deprecated
 public class VanillaPublicMetricsTests {
 
 	@Test
@@ -49,38 +46,36 @@ public class VanillaPublicMetricsTests {
 		for (Metric<?> metric : publicMetrics.metrics()) {
 			results.put(metric.getName(), metric);
 		}
+		assertTrue(results.containsKey("mem"));
+		assertTrue(results.containsKey("mem.free"));
 		assertThat(results.get("a").getValue().doubleValue(), equalTo(0.5));
 	}
 
 	@Test
-	public void testAdditionalMetrics() throws Exception {
+	public void testSystemMetrics() throws Exception {
 		InMemoryMetricRepository repository = new InMemoryMetricRepository();
-		Collection<PublicMetrics> allMetrics = new ArrayList<PublicMetrics>();
+		repository.set(new Metric<Double>("a", 0.5, new Date()));
-		allMetrics.add(new ImmutablePublicMetrics(new Metric<Number>("first", 2L)));
+		VanillaPublicMetrics publicMetrics = new VanillaPublicMetrics(repository);
-		allMetrics.add(new ImmutablePublicMetrics(new Metric<Number>("second", 4L)));
-
-		VanillaPublicMetrics publicMetrics = new VanillaPublicMetrics(repository, allMetrics);
 		Map<String, Metric<?>> results = new HashMap<String, Metric<?>>();
 		for (Metric<?> metric : publicMetrics.metrics()) {
 			results.put(metric.getName(), metric);
 		}
-		assertTrue(results.containsKey("first"));
+		assertTrue(results.containsKey("mem"));
-		assertTrue(results.containsKey("second"));
+		assertTrue(results.containsKey("mem.free"));
-		assertEquals(2, results.size());
+		assertTrue(results.containsKey("processors"));
-	}
+		assertTrue(results.containsKey("uptime"));
 
+		assertTrue(results.containsKey("heap.committed"));
+		assertTrue(results.containsKey("heap.init"));
+		assertTrue(results.containsKey("heap.used"));
+		assertTrue(results.containsKey("heap"));
 
-	private static class ImmutablePublicMetrics implements PublicMetrics {
+		assertTrue(results.containsKey("threads.peak"));
-		private final Collection<Metric<?>> metrics;
+		assertTrue(results.containsKey("threads.daemon"));
+		assertTrue(results.containsKey("threads"));
 
-		private ImmutablePublicMetrics(Metric<?> metrics) {
+		assertTrue(results.containsKey("classes.loaded"));
-			this.metrics = new LinkedHashSet<Metric<?>>();
+		assertTrue(results.containsKey("classes.unloaded"));
-			this.metrics.addAll(Arrays.asList(metrics));
+		assertTrue(results.containsKey("classes"));
-		}
-
-		@Override
-		public Collection<Metric<?>> metrics() {
-			return metrics;
-		}
 	}
 }

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

@@ -585,12 +585,12 @@ Spring Boot Actuator includes a metrics service with ``gauge'' and ``counter'' s
 A ``gauge'' records a single value; and a ``counter'' records a delta (an increment or
 decrement). Spring Boot Actuator also provides a
 {sc-spring-boot-actuator}/endpoint/PublicMetrics.{sc-ext}[`PublicMetrics`] interface that
-you can implement to expose metrics that you cannot record via one of those two mechanisms. Look
+you can implement to expose metrics that you cannot record via one of those two
-at {sc-spring-boot-actuator}/endpoint/SystemPublicMetrics.{sc-ext}[`SystemPublicMetrics`]
+mechanisms. Look at {sc-spring-boot-actuator}/endpoint/SystemPublicMetrics.{sc-ext}[`SystemPublicMetrics`]
 for an example.
 
-Metrics for all HTTP requests are automatically recorded, so if you hit the
+Metrics for all HTTP requests are automatically recorded, so if you hit the `metrics`
-`metrics` endpoint you should see a response similar to this:
+endpoint you should see a response similar to this:
 
 [source,json,indent=0]
 ----
@@ -668,15 +668,17 @@ TIP: You can use any string as a metric name but you should follow guidelines of
 store/graphing technology. Some good guidelines for Graphite are available on
 http://matt.aimonetti.net/posts/2013/06/26/practical-guide-to-graphite-monitoring/[Matt Aimonetti's Blog].
 
+
+
 [[production-ready-public-metrics]]
 === Adding your own public metrics
-
 To add additional metrics that are computed every time the metrics endpoint is invoked,
 simply register additional `PublicMetrics` implementation bean(s). By default, all such
 beans are gathered by the endpoint. You can easily change that by defining your own
 `MetricsEndpoint`.
 
 
+
 [[production-ready-metric-repositories]]
 === Metric repositories
 Metric service implementations are usually bound to a