Rename gateway client observation metric to avoid WebClient conflict

Renames DefaultGatewayObservationConvention's metric from
'http.client.requests' to 'spring.cloud.gateway.http.client.requests'
so it no longer collides with Spring Web's
DefaultClientRequestObservationConvention, which uses the same name
with a different low-cardinality label set and causes Prometheus to
drop one of the two series.

Fixes gh-3153

Signed-off-by: JooYoung Jung <143606756+LivingLikeKrillin@users.noreply.github.com>

Author: LivingLikeKrillin

spring-cloud-gateway-server-webflux/src/main/java/org/springframework/cloud/gateway/filter/headers/observation/DefaultGatewayObservationConvention.java

@@ -72,7 +72,7 @@ public KeyValues getHighCardinalityKeyValues(GatewayContext context) {
 
 	@Override
 	public String getName() {
-		return "http.client.requests";
+		return "spring.cloud.gateway.http.client.requests";
 	}
 
 	@Override

spring-cloud-gateway-server-webflux/src/test/java/org/springframework/cloud/gateway/filter/headers/observation/DefaultGatewayObservationConventionTests.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2013-present 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.cloud.gateway.filter.headers.observation;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class DefaultGatewayObservationConventionTests {
+
+	@Test
+	void getName_returnsSpringCloudGatewayPrefixedName() {
+		assertThat(DefaultGatewayObservationConvention.INSTANCE.getName())
+			.isEqualTo("spring.cloud.gateway.http.client.requests");
+	}
+
+}

spring-cloud-gateway-server-webflux/src/test/java/org/springframework/cloud/gateway/filter/headers/observation/ObservedHttpHeadersFilterTests.java

@@ -99,11 +99,12 @@ public SampleTestRunnerConsumer yourCode() throws Exception {
 							.hasTag("spring.cloud.gateway.route.uri", "http://localhost:8080/")
 							.hasTag("spring.cloud.gateway.route.id", "foo"));
 			MeterRegistryAssert.then(meterRegistry)
-				.hasTimerWithNameAndTags("http.client.requests",
+				.hasTimerWithNameAndTags("spring.cloud.gateway.http.client.requests",
 						Tags.of("spring.cloud.gateway.route.id", "foo", "error", "none", "http.method", "GET",
 								"http.status_code", "200", "spring.cloud.gateway.route.uri", "http://localhost:8080/"))
-				.hasMeterWithNameAndTags("http.client.requests.active", Tags.of("spring.cloud.gateway.route.id", "foo",
-						"http.method", "GET", "spring.cloud.gateway.route.uri", "http://localhost:8080/"));
+				.hasMeterWithNameAndTags("spring.cloud.gateway.http.client.requests.active",
+						Tags.of("spring.cloud.gateway.route.id", "foo", "http.method", "GET",
+								"spring.cloud.gateway.route.uri", "http://localhost:8080/"));
 		};
 	}