Add metric to include the path as a Gateway metric Tag

Fixes gh-2419

docs/src/main/asciidoc/_configprops.adoc

@@ -107,6 +107,7 @@
 |spring.cloud.gateway.metrics.enabled | `false` | Enables the collection of metrics data.
 |spring.cloud.gateway.metrics.prefix | `spring.cloud.gateway` | The prefix of all metrics emitted by gateway.
 |spring.cloud.gateway.metrics.tags |  | Tags map that added to metrics.
+|spring.cloud.gateway.metrics.tags.path.enabled | `false` | If the collection of metrics data is enabled, enables an extra metric data tag by path.
 |spring.cloud.gateway.predicate.after.enabled | `true` | Enables the after predicate.
 |spring.cloud.gateway.predicate.before.enabled | `true` | Enables the before predicate.
 |spring.cloud.gateway.predicate.between.enabled | `true` | Enables the between predicate.

docs/src/main/asciidoc/spring-cloud-gateway.adoc

@@ -1898,6 +1898,10 @@ To enable gateway metrics, add spring-boot-starter-actuator as a project depende
 * `httpStatusCode`: The HTTP Status of the request returned to the client.
 * `httpMethod`: The HTTP method used for the request.
 
+In addition, through the property `spring.cloud.gateway.metrics.tags.path.enabled` (by default, set to false), you can activate an extra metric with the tag:
+
+* `path`: Path of the request.
+
 These metrics are then available to be scraped from `/actuator/metrics/spring.cloud.gateway.requests` and can be easily integrated with Prometheus to create a link:images/gateway-grafana-dashboard.jpeg[Grafana] link:gateway-grafana-dashboard.json[dashboard].
 
 NOTE: To enable the prometheus endpoint, add `micrometer-registry-prometheus` as a project dependency.

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/config/GatewayMetricsAutoConfiguration.java

@@ -33,6 +33,7 @@ import org.springframework.cloud.gateway.filter.GatewayMetricsFilter;
 import org.springframework.cloud.gateway.route.RouteDefinitionLocator;
 import org.springframework.cloud.gateway.route.RouteDefinitionMetrics;
 import org.springframework.cloud.gateway.support.tagsprovider.GatewayHttpTagsProvider;
+import org.springframework.cloud.gateway.support.tagsprovider.GatewayPathTagsProvider;
 import org.springframework.cloud.gateway.support.tagsprovider.GatewayRouteTagsProvider;
 import org.springframework.cloud.gateway.support.tagsprovider.GatewayTagsProvider;
 import org.springframework.cloud.gateway.support.tagsprovider.PropertiesTagsProvider;
@@ -53,6 +54,12 @@ public class GatewayMetricsAutoConfiguration {
 		return new GatewayHttpTagsProvider();
 	}
 
+	@Bean
+	@ConditionalOnProperty(name = GatewayProperties.PREFIX + ".metrics.tags.path.enabled")
+	public GatewayPathTagsProvider gatewayPathTagsProvider() {
+		return new GatewayPathTagsProvider();
+	}
+
 	@Bean
 	public GatewayRouteTagsProvider gatewayRouteTagsProvider() {
 		return new GatewayRouteTagsProvider();

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/support/tagsprovider/GatewayPathTagsProvider.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2013-2020 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.support.tagsprovider;
+
+import io.micrometer.core.instrument.Tags;
+
+import org.springframework.cloud.gateway.route.Route;
+import org.springframework.web.server.ServerWebExchange;
+
+import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.GATEWAY_ROUTE_ATTR;
+
+/**
+ * @author Marta Medio
+ * @author Alberto C. Ríos
+ */
+public class GatewayPathTagsProvider implements GatewayTagsProvider {
+
+	private static final String START_PATH_PATTERN = "Paths: [";
+
+	private static final String END_PATH_PATTERN = "], match";
+
+	@Override
+	public Tags apply(ServerWebExchange exchange) {
+		Route route = exchange.getAttribute(GATEWAY_ROUTE_ATTR);
+
+		if (route != null) {
+			String rawPredicate = route.getPredicate().toString();
+			if (predicateContainsPath(rawPredicate)) {
+				int beginIndex = rawPredicate.indexOf(START_PATH_PATTERN) + START_PATH_PATTERN.length();
+				String predicate = rawPredicate.substring(beginIndex, rawPredicate.indexOf(END_PATH_PATTERN));
+				return Tags.of("path", predicate);
+			}
+		}
+
+		return Tags.empty();
+	}
+
+	private boolean predicateContainsPath(String rawPredicate) {
+		return rawPredicate != null && rawPredicate.contains(START_PATH_PATTERN)
+				&& rawPredicate.contains(END_PATH_PATTERN);
+	}
+
+}

spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/support/tagsprovider/GatewayPathTagsProviderTests.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2013-2020 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.support.tagsprovider;
+
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import io.micrometer.core.instrument.Tags;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.cloud.gateway.handler.predicate.MethodRoutePredicateFactory;
+import org.springframework.cloud.gateway.handler.predicate.PathRoutePredicateFactory;
+import org.springframework.cloud.gateway.route.Route;
+import org.springframework.http.HttpMethod;
+import org.springframework.mock.http.server.reactive.MockServerHttpRequest;
+import org.springframework.mock.web.server.MockServerWebExchange;
+import org.springframework.web.server.ServerWebExchange;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.GATEWAY_ROUTE_ATTR;
+
+/**
+ * @author Marta Medio
+ * @author Alberto C. Ríos
+ */
+public class GatewayPathTagsProviderTests {
+
+	private final GatewayPathTagsProvider pathTagsProvider = new GatewayPathTagsProvider();
+
+	private static final String ROUTE_URI = "http://gatewaytagsprovider.org:80";
+
+	@Test
+	void addPathToRoutes() {
+		List<String> pathList = Stream.of("/git/**").collect(Collectors.toList());
+
+		Route route = Route.async().id("git").uri(ROUTE_URI).predicate(
+				new PathRoutePredicateFactory().apply(new PathRoutePredicateFactory.Config().setPatterns(pathList)))
+				.build();
+
+		ServerWebExchange exchange = MockServerWebExchange.from(MockServerHttpRequest.get(ROUTE_URI).build());
+		exchange.getAttributes().put(GATEWAY_ROUTE_ATTR, route);
+
+		Tags tags = pathTagsProvider.apply(exchange);
+		assertThat(tags.stream().count()).isEqualTo(1);
+		assertThat(tags.stream().anyMatch(tag -> "path".equals(tag.getKey()))).isEqualTo(true);
+	}
+
+	@Test
+	void ignoreRoutesWithoutPath() {
+		MethodRoutePredicateFactory.Config config = new MethodRoutePredicateFactory.Config();
+		config.setMethods(HttpMethod.GET);
+		Route route = Route.async().id("empty").uri(ROUTE_URI)
+				.predicate(new MethodRoutePredicateFactory().apply(config)).build();
+
+		ServerWebExchange exchange = MockServerWebExchange.from(MockServerHttpRequest.get(ROUTE_URI).build());
+		exchange.getAttributes().put(GATEWAY_ROUTE_ATTR, route);
+
+		Tags tags = pathTagsProvider.apply(exchange);
+		assertThat(tags.stream().count()).isEqualTo(0);
+	}
+
+}