Merge pull request #11316 from dkublik:adding-MetricsClientHttpRequestInterceptor-only-once

* pr/11316:
  Polish
  Avoid duplicate Metrics HTTP interceptor registration

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

@@ -59,10 +59,13 @@ public class MetricsRestTemplateCustomizer implements RestTemplateCustomizer {
 		UriTemplateHandler templateHandler = restTemplate.getUriTemplateHandler();
 		templateHandler = this.interceptor.createUriTemplateHandler(templateHandler);
 		restTemplate.setUriTemplateHandler(templateHandler);
+		List<ClientHttpRequestInterceptor> existingInterceptors = restTemplate.getInterceptors();
+		if (!existingInterceptors.contains(this.interceptor)) {
 		List<ClientHttpRequestInterceptor> interceptors = new ArrayList<>();
-		interceptors.add(this.interceptor);
-		interceptors.addAll(restTemplate.getInterceptors());
-		restTemplate.setInterceptors(interceptors);
+			interceptors.add(this.interceptor);
+			interceptors.addAll(existingInterceptors);
+			restTemplate.setInterceptors(interceptors);
+		}
 	}
 
 }

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

@@ -24,6 +24,7 @@ import io.micrometer.core.instrument.Statistic;
 import io.micrometer.core.instrument.Tag;
 import io.micrometer.core.instrument.simple.SimpleConfig;
 import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
+import org.junit.Before;
 import org.junit.Test;
 
 import org.springframework.http.HttpMethod;
@@ -39,35 +40,54 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Tests for {@link MetricsRestTemplateCustomizer}.
  *
  * @author Jon Schneider
+ * @author Brian Clozel
  */
 public class MetricsRestTemplateCustomizerTests {
 
+	private MeterRegistry registry;
+
+	private RestTemplate restTemplate;
+
+	@Before
+	public void setup() {
+		this.registry = new SimpleMeterRegistry(SimpleConfig.DEFAULT, new MockClock());
+		this.restTemplate = new RestTemplate();
+	}
+
 	@Test
 	public void interceptRestTemplate() {
-		MeterRegistry registry = new SimpleMeterRegistry(SimpleConfig.DEFAULT,
-				new MockClock());
-		RestTemplate restTemplate = new RestTemplate();
 		MetricsRestTemplateCustomizer customizer = new MetricsRestTemplateCustomizer(
-				registry, new DefaultRestTemplateExchangeTagsProvider(),
+				this.registry, new DefaultRestTemplateExchangeTagsProvider(),
 				"http.client.requests", true);
-		customizer.customize(restTemplate);
+		customizer.customize(this.restTemplate);
 		MockRestServiceServer mockServer = MockRestServiceServer
-				.createServer(restTemplate);
+				.createServer(this.restTemplate);
 		mockServer.expect(MockRestRequestMatchers.requestTo("/test/123"))
 				.andExpect(MockRestRequestMatchers.method(HttpMethod.GET))
 				.andRespond(MockRestResponseCreators.withSuccess("OK",
 						MediaType.APPLICATION_JSON));
-		String result = restTemplate.getForObject("/test/{id}", String.class, 123);
-		MockClock.clock(registry).add(SimpleConfig.DEFAULT_STEP);
-		assertThat(registry.find("http.client.requests")
+		String result = this.restTemplate.getForObject("/test/{id}", String.class, 123);
+		MockClock.clock(this.registry).add(SimpleConfig.DEFAULT_STEP);
+		assertThat(this.registry.find("http.client.requests")
 				.meters()).anySatisfy((m) -> assertThat(
-						StreamSupport.stream(m.getId().getTags().spliterator(), false)
-								.map(Tag::getKey)).doesNotContain("bucket"));
-		assertThat(registry.find("http.client.requests")
+				StreamSupport.stream(m.getId().getTags().spliterator(), false)
+						.map(Tag::getKey)).doesNotContain("bucket"));
+		assertThat(this.registry.find("http.client.requests")
 				.tags("method", "GET", "uri", "/test/{id}", "status", "200")
 				.value(Statistic.Count, 1.0).timer()).isPresent();
 		assertThat(result).isEqualTo("OK");
 		mockServer.verify();
 	}
 
+	@Test
+	public void avoidDuplicateRegistration() {
+		MetricsRestTemplateCustomizer customizer = new MetricsRestTemplateCustomizer(
+				this.registry, new DefaultRestTemplateExchangeTagsProvider(),
+				"http.client.requests", true);
+		customizer.customize(this.restTemplate);
+		assertThat(this.restTemplate.getInterceptors()).hasSize(1);
+		customizer.customize(this.restTemplate);
+		assertThat(this.restTemplate.getInterceptors()).hasSize(1);
+	}
+
 }