Auto-configure observations for RestClients

Closes gh-38500

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/observation/web/client/HttpClientObservationsAutoConfiguration.java

@@ -31,6 +31,7 @@ import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.web.client.RestClientAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
@@ -48,13 +49,15 @@ import org.springframework.core.annotation.Order;
  * @author Stephane Nicoll
  * @author Raheela Aslam
  * @author Brian Clozel
+ * @author Moritz Halbritter
  * @since 3.0.0
  */
 @AutoConfiguration(after = { ObservationAutoConfiguration.class, CompositeMeterRegistryAutoConfiguration.class,
-		RestTemplateAutoConfiguration.class, WebClientAutoConfiguration.class })
+		RestTemplateAutoConfiguration.class, WebClientAutoConfiguration.class, RestClientAutoConfiguration.class })
 @ConditionalOnClass(Observation.class)
 @ConditionalOnBean(ObservationRegistry.class)
-@Import({ RestTemplateObservationConfiguration.class, WebClientObservationConfiguration.class })
+@Import({ RestTemplateObservationConfiguration.class, WebClientObservationConfiguration.class,
+		RestClientObservationConfiguration.class })
 @EnableConfigurationProperties({ MetricsProperties.class, ObservationProperties.class })
 public class HttpClientObservationsAutoConfiguration {
 

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/observation/web/client/RestClientObservationConfiguration.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2012-2023 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.client;
+
+import io.micrometer.observation.ObservationRegistry;
+
+import org.springframework.beans.factory.ObjectProvider;
+import org.springframework.boot.actuate.autoconfigure.observation.ObservationProperties;
+import org.springframework.boot.actuate.metrics.web.client.ObservationRestClientCustomizer;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.web.client.RestClientCustomizer;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.http.client.observation.ClientRequestObservationConvention;
+import org.springframework.http.client.observation.DefaultClientRequestObservationConvention;
+import org.springframework.web.client.RestClient;
+
+/**
+ * Configure the instrumentation of {@link RestClient}.
+ *
+ * @author Moritz Halbritter
+ */
+@Configuration(proxyBeanMethods = false)
+@ConditionalOnClass(RestClient.class)
+@ConditionalOnBean(RestClient.Builder.class)
+class RestClientObservationConfiguration {
+
+	@Bean
+	RestClientCustomizer observationRestClientCustomizer(ObservationRegistry observationRegistry,
+			ObjectProvider<ClientRequestObservationConvention> customConvention,
+			ObservationProperties observationProperties) {
+		String name = observationProperties.getHttp().getClient().getRequests().getName();
+		ClientRequestObservationConvention observationConvention = customConvention
+			.getIfAvailable(() -> new DefaultClientRequestObservationConvention(name));
+		return new ObservationRestClientCustomizer(observationRegistry, observationConvention);
+	}
+
+}

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/observation/web/client/RestTemplateObservationConfiguration.java

@@ -19,7 +19,6 @@ package org.springframework.boot.actuate.autoconfigure.observation.web.client;
 import io.micrometer.observation.ObservationRegistry;
 
 import org.springframework.beans.factory.ObjectProvider;
-import org.springframework.boot.actuate.autoconfigure.metrics.MetricsProperties;
 import org.springframework.boot.actuate.autoconfigure.observation.ObservationProperties;
 import org.springframework.boot.actuate.metrics.web.client.ObservationRestTemplateCustomizer;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
@@ -44,7 +43,7 @@ class RestTemplateObservationConfiguration {
 	@Bean
 	ObservationRestTemplateCustomizer observationRestTemplateCustomizer(ObservationRegistry observationRegistry,
 			ObjectProvider<ClientRequestObservationConvention> customConvention,
-			ObservationProperties observationProperties, MetricsProperties metricsProperties) {
+			ObservationProperties observationProperties) {
 		String name = observationProperties.getHttp().getClient().getRequests().getName();
 		ClientRequestObservationConvention observationConvention = customConvention
 			.getIfAvailable(() -> new DefaultClientRequestObservationConvention(name));

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/observation/web/client/RestClientObservationConfigurationTests.java

@@ -0,0 +1,175 @@
+/*
+ * Copyright 2012-2023 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.client;
+
+import io.micrometer.common.KeyValues;
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.observation.ObservationRegistry;
+import io.micrometer.observation.tck.TestObservationRegistry;
+import io.micrometer.observation.tck.TestObservationRegistryAssert;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import org.springframework.boot.actuate.autoconfigure.metrics.test.MetricsRun;
+import org.springframework.boot.actuate.autoconfigure.observation.ObservationAutoConfiguration;
+import org.springframework.boot.actuate.metrics.web.client.ObservationRestClientCustomizer;
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.autoconfigure.web.client.RestClientAutoConfiguration;
+import org.springframework.boot.test.context.assertj.AssertableApplicationContext;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.boot.test.system.CapturedOutput;
+import org.springframework.boot.test.system.OutputCaptureExtension;
+import org.springframework.boot.test.web.client.MockServerRestClientCustomizer;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.client.observation.ClientRequestObservationContext;
+import org.springframework.http.client.observation.DefaultClientRequestObservationConvention;
+import org.springframework.test.web.client.MockRestServiceServer;
+import org.springframework.web.client.RestClient;
+import org.springframework.web.client.RestClient.Builder;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.test.web.client.match.MockRestRequestMatchers.requestTo;
+import static org.springframework.test.web.client.response.MockRestResponseCreators.withStatus;
+
+/**
+ * Tests for {@link RestClientObservationConfiguration}.
+ *
+ * @author Brian Clozel
+ * @author Moritz Halbritter
+ */
+@ExtendWith(OutputCaptureExtension.class)
+class RestClientObservationConfigurationTests {
+
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
+		.withBean(ObservationRegistry.class, TestObservationRegistry::create)
+		.withConfiguration(AutoConfigurations.of(ObservationAutoConfiguration.class, RestClientAutoConfiguration.class,
+				HttpClientObservationsAutoConfiguration.class));
+
+	@Test
+	void contributesCustomizerBean() {
+		this.contextRunner.run((context) -> assertThat(context).hasSingleBean(ObservationRestClientCustomizer.class));
+	}
+
+	@Test
+	void restClientCreatedWithBuilderIsInstrumented() {
+		this.contextRunner.run((context) -> {
+			RestClient restClient = buildRestClient(context);
+			restClient.get().uri("/projects/{project}", "spring-boot").retrieve().toBodilessEntity();
+			TestObservationRegistry registry = context.getBean(TestObservationRegistry.class);
+			TestObservationRegistryAssert.assertThat(registry)
+				.hasObservationWithNameEqualToIgnoringCase("http.client.requests");
+		});
+	}
+
+	@Test
+	void restClientCreatedWithBuilderUsesCustomConventionName() {
+		final String observationName = "test.metric.name";
+		this.contextRunner.withPropertyValues("management.observations.http.client.requests.name=" + observationName)
+			.run((context) -> {
+				RestClient restClient = buildRestClient(context);
+				restClient.get().uri("/projects/{project}", "spring-boot").retrieve().toBodilessEntity();
+				TestObservationRegistry registry = context.getBean(TestObservationRegistry.class);
+				TestObservationRegistryAssert.assertThat(registry)
+					.hasObservationWithNameEqualToIgnoringCase(observationName);
+			});
+	}
+
+	@Test
+	void restClientCreatedWithBuilderUsesCustomConvention() {
+		this.contextRunner.withUserConfiguration(CustomConvention.class).run((context) -> {
+			RestClient restClient = buildRestClient(context);
+			restClient.get().uri("/projects/{project}", "spring-boot").retrieve().toBodilessEntity();
+			TestObservationRegistry registry = context.getBean(TestObservationRegistry.class);
+			TestObservationRegistryAssert.assertThat(registry)
+				.hasObservationWithNameEqualTo("http.client.requests")
+				.that()
+				.hasLowCardinalityKeyValue("project", "spring-boot");
+		});
+	}
+
+	@Test
+	void afterMaxUrisReachedFurtherUrisAreDenied(CapturedOutput output) {
+		this.contextRunner.with(MetricsRun.simple())
+			.withPropertyValues("management.metrics.web.client.max-uri-tags=2")
+			.run((context) -> {
+				RestClientWithMockServer restClientWithMockServer = buildRestClientAndMockServer(context);
+				MockRestServiceServer server = restClientWithMockServer.mockServer();
+				RestClient restClient = restClientWithMockServer.restClient();
+				for (int i = 0; i < 3; i++) {
+					server.expect(requestTo("/test/" + i)).andRespond(withStatus(HttpStatus.OK));
+				}
+				for (int i = 0; i < 3; i++) {
+					restClient.get().uri("/test/" + i, String.class).retrieve().toBodilessEntity();
+				}
+				TestObservationRegistry registry = context.getBean(TestObservationRegistry.class);
+				TestObservationRegistryAssert.assertThat(registry)
+					.hasNumberOfObservationsWithNameEqualTo("http.client.requests", 3);
+				MeterRegistry meterRegistry = context.getBean(MeterRegistry.class);
+				assertThat(meterRegistry.find("http.client.requests").timers()).hasSize(2);
+				assertThat(output).contains("Reached the maximum number of URI tags for 'http.client.requests'.")
+					.contains("Are you using 'uriVariables'?");
+			});
+	}
+
+	@Test
+	void backsOffWhenRestClientBuilderIsMissing() {
+		new ApplicationContextRunner().with(MetricsRun.simple())
+			.withConfiguration(AutoConfigurations.of(ObservationAutoConfiguration.class,
+					HttpClientObservationsAutoConfiguration.class))
+			.run((context) -> assertThat(context).doesNotHaveBean(ObservationRestClientCustomizer.class));
+	}
+
+	private RestClient buildRestClient(AssertableApplicationContext context) {
+		RestClientWithMockServer restClientWithMockServer = buildRestClientAndMockServer(context);
+		restClientWithMockServer.mockServer()
+			.expect(requestTo("/projects/spring-boot"))
+			.andRespond(withStatus(HttpStatus.OK));
+		return restClientWithMockServer.restClient();
+	}
+
+	private RestClientWithMockServer buildRestClientAndMockServer(AssertableApplicationContext context) {
+		Builder builder = context.getBean(Builder.class);
+		MockServerRestClientCustomizer customizer = new MockServerRestClientCustomizer();
+		customizer.customize(builder);
+		return new RestClientWithMockServer(builder.build(), customizer.getServer());
+	}
+
+	private record RestClientWithMockServer(RestClient restClient, MockRestServiceServer mockServer) {
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	static class CustomConventionConfiguration {
+
+		@Bean
+		CustomConvention customConvention() {
+			return new CustomConvention();
+		}
+
+	}
+
+	static class CustomConvention extends DefaultClientRequestObservationConvention {
+
+		@Override
+		public KeyValues getLowCardinalityKeyValues(ClientRequestObservationContext context) {
+			return super.getLowCardinalityKeyValues(context).and("project", "spring-boot");
+		}
+
+	}
+
+}

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/observation/web/client/RestClientObservationConfigurationWithoutMetricsTests.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2012-2023 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.client;
+
+import io.micrometer.observation.ObservationRegistry;
+import io.micrometer.observation.tck.TestObservationRegistry;
+import io.micrometer.observation.tck.TestObservationRegistryAssert;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import org.springframework.boot.actuate.autoconfigure.observation.ObservationAutoConfiguration;
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.autoconfigure.web.client.RestClientAutoConfiguration;
+import org.springframework.boot.test.context.assertj.AssertableApplicationContext;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.boot.test.system.OutputCaptureExtension;
+import org.springframework.boot.test.web.client.MockServerRestClientCustomizer;
+import org.springframework.boot.testsupport.classpath.ClassPathExclusions;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.client.RestClient;
+import org.springframework.web.client.RestClient.Builder;
+
+import static org.springframework.test.web.client.match.MockRestRequestMatchers.requestTo;
+import static org.springframework.test.web.client.response.MockRestResponseCreators.withStatus;
+
+/**
+ * Tests for {@link RestClientObservationConfiguration} without Micrometer Metrics.
+ *
+ * @author Brian Clozel
+ * @author Andy Wilkinson
+ * @author Moritz Halbritter
+ */
+@ExtendWith(OutputCaptureExtension.class)
+@ClassPathExclusions("micrometer-core-*.jar")
+class RestClientObservationConfigurationWithoutMetricsTests {
+
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
+		.withBean(ObservationRegistry.class, TestObservationRegistry::create)
+		.withConfiguration(AutoConfigurations.of(ObservationAutoConfiguration.class, RestClientAutoConfiguration.class,
+				HttpClientObservationsAutoConfiguration.class));
+
+	@Test
+	void restClientCreatedWithBuilderIsInstrumented() {
+		this.contextRunner.run((context) -> {
+			RestClient restClient = buildRestClient(context);
+			restClient.get().uri("/projects/{project}", "spring-boot").retrieve().toBodilessEntity();
+			TestObservationRegistry registry = context.getBean(TestObservationRegistry.class);
+			TestObservationRegistryAssert.assertThat(registry)
+				.hasObservationWithNameEqualToIgnoringCase("http.client.requests");
+		});
+	}
+
+	private RestClient buildRestClient(AssertableApplicationContext context) {
+		Builder builder = context.getBean(Builder.class);
+		MockServerRestClientCustomizer customizer = new MockServerRestClientCustomizer();
+		customizer.customize(builder);
+		customizer.getServer().expect(requestTo("/projects/spring-boot")).andRespond(withStatus(HttpStatus.OK));
+		return builder.build();
+	}
+
+}

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/client/ObservationRestClientCustomizer.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2012-2023 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.metrics.web.client;
+
+import io.micrometer.observation.ObservationRegistry;
+
+import org.springframework.boot.web.client.RestClientCustomizer;
+import org.springframework.http.client.observation.ClientRequestObservationConvention;
+import org.springframework.util.Assert;
+import org.springframework.web.client.RestClient.Builder;
+
+/**
+ * {@link RestClientCustomizer} that configures the {@link Builder RestClient builder} to
+ * record request observations.
+ *
+ * @author Moritz Halbritter
+ * @since 3.2.0
+ */
+public class ObservationRestClientCustomizer implements RestClientCustomizer {
+
+	private final ObservationRegistry observationRegistry;
+
+	private final ClientRequestObservationConvention observationConvention;
+
+	/**
+	 * Create a new {@link ObservationRestClientCustomizer}.
+	 * @param observationRegistry the observation registry
+	 * @param observationConvention the observation convention
+	 */
+	public ObservationRestClientCustomizer(ObservationRegistry observationRegistry,
+			ClientRequestObservationConvention observationConvention) {
+		Assert.notNull(observationConvention, "ObservationConvention must not be null");
+		Assert.notNull(observationRegistry, "ObservationRegistry must not be null");
+		this.observationRegistry = observationRegistry;
+		this.observationConvention = observationConvention;
+	}
+
+	@Override
+	public void customize(Builder restClientBuilder) {
+		restClientBuilder.observationRegistry(this.observationRegistry);
+		restClientBuilder.observationConvention(this.observationConvention);
+	}
+
+}

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/web/client/ObservationRestClientCustomizerTests.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2012-2023 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.metrics.web.client;
+
+import io.micrometer.observation.ObservationRegistry;
+import io.micrometer.observation.tck.TestObservationRegistry;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.http.client.observation.DefaultClientRequestObservationConvention;
+import org.springframework.web.client.RestClient;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link ObservationRestClientCustomizer}.
+ *
+ * @author Brian Clozel
+ * @author Moritz Halbritter
+ */
+class ObservationRestClientCustomizerTests {
+
+	private static final String TEST_METRIC_NAME = "http.test.metric.name";
+
+	private final ObservationRegistry observationRegistry = TestObservationRegistry.create();
+
+	private final RestClient.Builder restClientBuilder = RestClient.builder();
+
+	private final ObservationRestClientCustomizer customizer = new ObservationRestClientCustomizer(
+			this.observationRegistry, new DefaultClientRequestObservationConvention(TEST_METRIC_NAME));
+
+	@Test
+	void shouldCustomizeObservationConfiguration() {
+		this.customizer.customize(this.restClientBuilder);
+		assertThat(this.restClientBuilder).hasFieldOrPropertyWithValue("observationRegistry", this.observationRegistry);
+		assertThat(this.restClientBuilder).extracting("observationConvention")
+			.isInstanceOf(DefaultClientRequestObservationConvention.class)
+			.hasFieldOrPropertyWithValue("name", TEST_METRIC_NAME);
+	}
+
+}

spring-boot-project/spring-boot-docs/src/docs/asciidoc/actuator/metrics.adoc

@@ -822,20 +822,21 @@ To customize the tags, provide a `@Bean` that implements `JerseyTagsProvider`.
 
 [[actuator.metrics.supported.http-clients]]
 ==== HTTP Client Metrics
-Spring Boot Actuator manages the instrumentation of both `RestTemplate` and `WebClient`.
+Spring Boot Actuator manages the instrumentation of `RestTemplate`, `WebClient` and `RestClient`.
 For that, you have to inject the auto-configured builder and use it to create instances:
 
 * `RestTemplateBuilder` for `RestTemplate`
 * `WebClient.Builder` for `WebClient`
+* `RestClient.Builder` for `RestClient`
 
-You can also manually apply the customizers responsible for this instrumentation, namely `ObservationRestTemplateCustomizer` and `ObservationWebClientCustomizer`.
+You can also manually apply the customizers responsible for this instrumentation, namely `ObservationRestTemplateCustomizer`, `ObservationWebClientCustomizer` and `ObservationRestClientCustomizer`.
 
 By default, metrics are generated with the name, `http.client.requests`.
 You can customize the name by setting the configprop:management.observations.http.client.requests.name[] property.
 
 See the {spring-framework-docs}/integration/observability.html#observability.http-client[Spring Framework reference documentation for more information on produced observations].
 
-To customize the tags when using `RestTemplate`, provide a `@Bean` that implements `ClientRequestObservationConvention` from the `org.springframework.http.client.observation` package.
+To customize the tags when using `RestTemplate` or `RestClient`, provide a `@Bean` that implements `ClientRequestObservationConvention` from the `org.springframework.http.client.observation` package.
 To customize the tags when using `WebClient`, provide a `@Bean` that implements `ClientRequestObservationConvention` from the `org.springframework.web.reactive.function.client` package.