Move MVC metrics to Observation auto-configuration

This commit moves the entire Metrics auto-configuration for Spring MVC
to the new `Observation` API and the instrumentation contributed in
Spring Framework.

Closes gh-32538

Author: bclozel

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/MetricsProperties.java

@@ -194,37 +194,18 @@ public static class ServerRequest {
 				 */
 				private String metricName = "http.server.requests";
 
-				/**
-				 * Whether the trailing slash should be ignored when recording metrics.
-				 */
-				private boolean ignoreTrailingSlash = true;
-
-				/**
-				 * Auto-timed request settings.
-				 */
-				@NestedConfigurationProperty
-				private final AutoTimeProperties autotime = new AutoTimeProperties();
-
-				public AutoTimeProperties getAutotime() {
-					return this.autotime;
-				}
-
+				@Deprecated(since = "3.0.0", forRemoval = true)
+				@DeprecatedConfigurationProperty(replacement = "management.observations.http.server.requests.name")
 				public String getMetricName() {
 					return this.metricName;
 				}
 
+				@Deprecated(since = "3.0.0", forRemoval = true)
+				@DeprecatedConfigurationProperty(replacement = "management.observations.http.server.requests.name")
 				public void setMetricName(String metricName) {
 					this.metricName = metricName;
 				}
 
-				public boolean isIgnoreTrailingSlash() {
-					return this.ignoreTrailingSlash;
-				}
-
-				public void setIgnoreTrailingSlash(boolean ignoreTrailingSlash) {
-					this.ignoreTrailingSlash = ignoreTrailingSlash;
-				}
-
 			}
 
 		}

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/jersey/JerseyServerMetricsAutoConfiguration.java

@@ -57,6 +57,7 @@
 @ConditionalOnClass({ ResourceConfig.class, MetricsApplicationEventListener.class })
 @ConditionalOnBean({ MeterRegistry.class, ResourceConfig.class })
 @EnableConfigurationProperties(MetricsProperties.class)
+@SuppressWarnings("removal")
 public class JerseyServerMetricsAutoConfiguration {
 
 	private final MetricsProperties properties;
@@ -75,9 +76,8 @@ public DefaultJerseyTagsProvider jerseyTagsProvider() {
 	public ResourceConfigCustomizer jerseyServerMetricsResourceConfigCustomizer(MeterRegistry meterRegistry,
 			JerseyTagsProvider tagsProvider) {
 		Server server = this.properties.getWeb().getServer();
-		return (config) -> config.register(
-				new MetricsApplicationEventListener(meterRegistry, tagsProvider, server.getRequest().getMetricName(),
-						server.getRequest().getAutotime().isEnabled(), new AnnotationUtilsAnnotationFinder()));
+		return (config) -> config.register(new MetricsApplicationEventListener(meterRegistry, tagsProvider,
+				server.getRequest().getMetricName(), true, new AnnotationUtilsAnnotationFinder()));
 	}
 
 	@Bean

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/web/reactive/WebFluxMetricsAutoConfiguration.java

@@ -51,6 +51,7 @@
 		SimpleMetricsExportAutoConfiguration.class })
 @ConditionalOnBean(MeterRegistry.class)
 @ConditionalOnWebApplication(type = ConditionalOnWebApplication.Type.REACTIVE)
+@SuppressWarnings("removal")
 public class WebFluxMetricsAutoConfiguration {
 
 	private final MetricsProperties properties;
@@ -62,15 +63,13 @@ public WebFluxMetricsAutoConfiguration(MetricsProperties properties) {
 	@Bean
 	@ConditionalOnMissingBean(WebFluxTagsProvider.class)
 	public DefaultWebFluxTagsProvider webFluxTagsProvider(ObjectProvider<WebFluxTagsContributor> contributors) {
-		return new DefaultWebFluxTagsProvider(this.properties.getWeb().getServer().getRequest().isIgnoreTrailingSlash(),
-				contributors.orderedStream().toList());
+		return new DefaultWebFluxTagsProvider(true, contributors.orderedStream().toList());
 	}
 
 	@Bean
 	public MetricsWebFilter webfluxMetrics(MeterRegistry registry, WebFluxTagsProvider tagConfigurer) {
 		ServerRequest request = this.properties.getWeb().getServer().getRequest();
-		return new MetricsWebFilter(registry, tagConfigurer, request.getMetricName(),
-				new PropertiesAutoTimer(request.getAutotime()));
+		return new MetricsWebFilter(registry, tagConfigurer, request.getMetricName(), new PropertiesAutoTimer(null));
 	}
 
 	@Bean

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/web/servlet/WebMvcMetricsAutoConfiguration.java

@@ -38,10 +38,16 @@ public static class Http {
 
 		private final Client client = new Client();
 
+		private final Server server = new Server();
+
 		public Client getClient() {
 			return this.client;
 		}
 
+		public Server getServer() {
+			return this.server;
+		}
+
 		public static class Client {
 
 			private final ClientRequests requests = new ClientRequests();
@@ -70,6 +76,34 @@ public void setName(String name) {
 
 		}
 
+		public static class Server {
+
+			private final ServerRequests requests = new ServerRequests();
+
+			public ServerRequests getRequests() {
+				return this.requests;
+			}
+
+			public static class ServerRequests {
+
+				/**
+				 * Name of the observation for server requests. If empty, will use the
+				 * default "http.server.requests".
+				 */
+				private String name;
+
+				public String getName() {
+					return this.name;
+				}
+
+				public void setName(String name) {
+					this.name = name;
+				}
+
+			}
+
+		}
+
 	}
 
 }

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/observation/ObservationProperties.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2012-2022 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
+ *
+ *      https://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.observation.web.servlet;
+
+import java.util.List;
+
+import io.micrometer.common.KeyValues;
+import io.micrometer.core.instrument.Tag;
+import io.micrometer.observation.Observation;
+
+import org.springframework.boot.actuate.metrics.web.servlet.DefaultWebMvcTagsProvider;
+import org.springframework.boot.actuate.metrics.web.servlet.WebMvcTagsContributor;
+import org.springframework.boot.actuate.metrics.web.servlet.WebMvcTagsProvider;
+import org.springframework.http.observation.ServerRequestObservationContext;
+import org.springframework.http.observation.ServerRequestObservationConvention;
+import org.springframework.util.Assert;
+import org.springframework.web.servlet.HandlerMapping;
+
+/**
+ * Adapter class that applies {@link WebMvcTagsProvider} tags as a
+ * {@link ServerRequestObservationConvention}.
+ *
+ * @author Brian Clozel
+ */
+@SuppressWarnings({ "deprecation", "removal" })
+class ServerRequestObservationConventionAdapter implements ServerRequestObservationConvention {
+
+	private final String observationName;
+
+	private final WebMvcTagsProvider tagsProvider;
+
+	ServerRequestObservationConventionAdapter(String observationName, WebMvcTagsProvider tagsProvider,
+			List<WebMvcTagsContributor> contributors) {
+		Assert.state((tagsProvider != null) || (contributors != null),
+				"adapter should adapt to a WebMvcTagsProvider or a list of contributors");
+		this.observationName = observationName;
+		this.tagsProvider = (tagsProvider != null) ? tagsProvider : new DefaultWebMvcTagsProvider(contributors);
+	}
+
+	@Override
+	public String getName() {
+		return this.observationName;
+	}
+
+	@Override
+	public boolean supportsContext(Observation.Context context) {
+		return context instanceof ServerRequestObservationContext;
+	}
+
+	@Override
+	public KeyValues getLowCardinalityKeyValues(ServerRequestObservationContext context) {
+		KeyValues keyValues = KeyValues.empty();
+		Iterable<Tag> tags = this.tagsProvider.getTags(context.getCarrier(), context.getResponse(), getHandler(context),
+				context.getError());
+		for (Tag tag : tags) {
+			keyValues = keyValues.and(tag.getKey(), tag.getValue());
+		}
+		return keyValues;
+	}
+
+	private Object getHandler(ServerRequestObservationContext context) {
+		return context.getCarrier().getAttribute(HandlerMapping.BEST_MATCHING_HANDLER_ATTRIBUTE);
+	}
+
+}