Add links to child paths for /actuator/gateway endpoint

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/actuate/AbstractGatewayControllerEndpoint.java

@@ -16,12 +16,16 @@
 
 package org.springframework.cloud.gateway.actuate;
 
+import java.io.IOException;
 import java.net.URI;
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -34,6 +38,7 @@ import org.springframework.cloud.gateway.filter.GlobalFilter;
 import org.springframework.cloud.gateway.filter.factory.GatewayFilterFactory;
 import org.springframework.cloud.gateway.handler.predicate.PredicateDefinition;
 import org.springframework.cloud.gateway.handler.predicate.RoutePredicateFactory;
+import org.springframework.cloud.gateway.route.Route;
 import org.springframework.cloud.gateway.route.RouteDefinition;
 import org.springframework.cloud.gateway.route.RouteDefinitionLocator;
 import org.springframework.cloud.gateway.route.RouteDefinitionWriter;
@@ -42,6 +47,9 @@ import org.springframework.cloud.gateway.support.NotFoundException;
 import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.context.ApplicationEventPublisherAware;
 import org.springframework.core.Ordered;
+import org.springframework.core.type.MethodMetadata;
+import org.springframework.core.type.classreading.MetadataReader;
+import org.springframework.core.type.classreading.SimpleMetadataReaderFactory;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.util.CollectionUtils;
@@ -51,6 +59,8 @@ import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.server.ResponseStatusException;
 
@@ -61,6 +71,8 @@ public class AbstractGatewayControllerEndpoint implements ApplicationEventPublis
 
 	private static final Log log = LogFactory.getLog(GatewayControllerEndpoint.class);
 
+	private static final String ENDPOINT_PREFIX = "/actuator/gateway";
+
 	protected RouteDefinitionLocator routeDefinitionLocator;
 
 	protected List<GlobalFilter> globalFilters;
@@ -88,6 +100,53 @@ public class AbstractGatewayControllerEndpoint implements ApplicationEventPublis
 		this.routeLocator = routeLocator;
 	}
 
+	private List<GatewayEndpointInfo> getAvailableEndpointsForClass(String className) {
+		try {
+			MetadataReader metadataReader = new SimpleMetadataReaderFactory().getMetadataReader(className);
+			Set<MethodMetadata> annotatedMethods = metadataReader.getAnnotationMetadata()
+					.getAnnotatedMethods(RequestMapping.class.getName());
+
+			return annotatedMethods.stream().map(method -> new GatewayEndpointInfo(ENDPOINT_PREFIX
+					+ ((String[]) method.getAnnotationAttributes(RequestMapping.class.getName()).get("path"))[0],
+					((RequestMethod[]) method.getAnnotationAttributes(RequestMapping.class.getName()).get("method"))[0]
+							.name()))
+					.collect(Collectors.toList());
+		}
+		catch (IOException exception) {
+			log.warn(exception.getMessage());
+			throw new ResponseStatusException(HttpStatus.INTERNAL_SERVER_ERROR, exception.getMessage());
+		}
+	}
+
+	public static List<GatewayEndpointInfo> mergeEndpoints(List<GatewayEndpointInfo> listA,
+			List<GatewayEndpointInfo> listB) {
+		Map<String, List<String>> mergedMap = new HashMap<>();
+
+		Stream.concat(listA.stream(), listB.stream()).forEach(e -> mergedMap
+				.computeIfAbsent(e.getHref(), k -> new ArrayList<>()).addAll(Arrays.asList(e.getMethods())));
+
+		return mergedMap.entrySet().stream().map(entry -> new GatewayEndpointInfo(entry.getKey(), entry.getValue()))
+				.collect(Collectors.toList());
+	}
+
+	GatewayEndpointInfo generateHref(Route r, GatewayEndpointInfo path) {
+		return new GatewayEndpointInfo(path.getHref().replace("{id}", r.getId()), Arrays.asList(path.getMethods()));
+	}
+
+	@GetMapping("/")
+	public Mono<List<GatewayEndpointInfo>> getEndpoints() {
+		List<GatewayEndpointInfo> endpoints = mergeEndpoints(
+				getAvailableEndpointsForClass(AbstractGatewayControllerEndpoint.class.getName()),
+				getAvailableEndpointsForClass(GatewayControllerEndpoint.class.getName()));
+
+		return Flux.fromIterable(endpoints).map(p -> p)
+				.flatMap(path -> this.routeLocator.getRoutes().map(r -> generateHref(r, path)).distinct().collectList()
+						.flatMapMany(Flux::fromIterable))
+				.distinct() // Ensure overall uniqueness
+				.collectList();
+
+	}
+
 	@Override
 	public void setApplicationEventPublisher(ApplicationEventPublisher publisher) {
 		this.publisher = publisher;

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/actuate/GatewayEndpointInfo.java

@@ -0,0 +1,71 @@
+/*
+ * 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.actuate;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+
+/**
+ * @author Marta Medio
+ */
+class GatewayEndpointInfo {
+
+	private String href;
+
+	private List<String> methods;
+
+	public String getHref() {
+		return href;
+	}
+
+	public void setHref(String href) {
+		this.href = href;
+	}
+
+	public String[] getMethods() {
+		return methods.stream().toArray(String[]::new);
+	}
+
+	GatewayEndpointInfo(String href, String method) {
+		this.href = href;
+		this.methods = Collections.singletonList(method);
+	}
+
+	GatewayEndpointInfo(String href, List<String> methods) {
+		this.href = href;
+		this.methods = methods;
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (this == o) {
+			return true;
+		}
+		if (o == null || getClass() != o.getClass()) {
+			return false;
+		}
+		GatewayEndpointInfo that = (GatewayEndpointInfo) o;
+		return Objects.equals(href, that.href) && Objects.equals(methods, that.methods);
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(href, methods);
+	}
+
+}

spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/actuate/GatewayControllerEndpointTests.java

@@ -68,6 +68,15 @@ public class GatewayControllerEndpointTests {
 	@LocalServerPort
 	int port;
 
+	@Test
+	public void testEndpoints() {
+		testClient.get().uri("http://localhost:" + port + "/actuator/gateway").exchange().expectStatus().isOk()
+				.expectBody(List.class).consumeWith(result -> {
+					List<String> responseBody = result.getResponseBody();
+					assertThat(responseBody).isNotEmpty();
+				});
+	}
+
 	@Test
 	public void testRefresh() {
 		testClient.post().uri("http://localhost:" + port + "/actuator/gateway/refresh").exchange().expectStatus()