Moves random uuid back to constructor, but only if config is set.

By default, no random ids will be generated.

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

@@ -51,6 +51,8 @@ NOTE: URIs defined in routes without a port will get a default port set to 80 an
 
 Spring Cloud Gateway matches routes as part of the Spring WebFlux `HandlerMapping` infrastructure. Spring Cloud Gateway includes many built-in Route Predicate Factories. All of these predicates match on different attributes of the HTTP request. Multiple Route Predicate Factories can be combined and are combined via logical `and`.
 
+WARNING: Previously, Spring Cloud Gateway generated a default Route ID by creating a random UUID. Generating a random UUID is a blocking operation and can lead to instability. Default id generation has been turned off by default. To re-enable this set an environment variable `SPRING_CLOUD_GATEWAY_ROUTE_GENERATE_ID` or system property `spring.cloud.gateway.route.generate-id` to `true`.
+
 === After Route Predicate Factory
 The After Route Predicate Factory takes one parameter, a datetime. This predicate matches requests that happen after the current datetime.
 

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/route/CompositeRouteDefinitionLocator.java

@@ -16,52 +16,22 @@
 
 package org.springframework.cloud.gateway.route;
 
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
 import reactor.core.publisher.Flux;
-import reactor.core.publisher.Mono;
-import reactor.core.scheduler.Schedulers;
-
-import org.springframework.util.AlternativeJdkIdGenerator;
-import org.springframework.util.IdGenerator;
 
 /**
  * @author Spencer Gibb
  */
 public class CompositeRouteDefinitionLocator implements RouteDefinitionLocator {
 
-	private static final Log log = LogFactory
-			.getLog(CompositeRouteDefinitionLocator.class);
-
 	private final Flux<RouteDefinitionLocator> delegates;
 
-	private final IdGenerator idGenerator;
-
 	public CompositeRouteDefinitionLocator(Flux<RouteDefinitionLocator> delegates) {
-		this(delegates, new AlternativeJdkIdGenerator());
-	}
-
-	public CompositeRouteDefinitionLocator(Flux<RouteDefinitionLocator> delegates,
-			IdGenerator idGenerator) {
 		this.delegates = delegates;
-		this.idGenerator = idGenerator;
 	}
 
 	@Override
 	public Flux<RouteDefinition> getRouteDefinitions() {
-		return this.delegates.flatMap(RouteDefinitionLocator::getRouteDefinitions)
-				.flatMap(routeDefinition -> Mono.justOrEmpty(routeDefinition.getId())
-						.defaultIfEmpty(idGenerator.generateId().toString())
-						.publishOn(Schedulers.elastic()).map(id -> {
-							if (routeDefinition.getId() == null) {
-								routeDefinition.setId(id);
-								if (log.isDebugEnabled()) {
-									log.debug(
-											"Id set on route definition: " + routeDefinition);
-								}
-							}
-							return routeDefinition;
-						}));
+		return this.delegates.flatMap(RouteDefinitionLocator::getRouteDefinitions);
 	}
 
 }

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/route/RouteDefinition.java

@@ -20,6 +20,7 @@ import java.net.URI;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
+import java.util.UUID;
 
 import javax.validation.Valid;
 import javax.validation.ValidationException;
@@ -38,6 +39,7 @@ import static org.springframework.util.StringUtils.tokenizeToStringArray;
 @Validated
 public class RouteDefinition {
 
+	@NotEmpty
 	private String id;
 
 	@NotEmpty
@@ -53,6 +55,13 @@ public class RouteDefinition {
 	private int order = 0;
 
 	public RouteDefinition() {
+		String envGenerateId = System.getenv("SPRING_CLOUD_GATEWAY_ROUTE_GENERATE_ID");
+		String propGenerateId = System
+				.getProperty("spring.cloud.gateway.route.generate-id", "false");
+		if ("true".equalsIgnoreCase(envGenerateId)
+				|| "true".equalsIgnoreCase(propGenerateId)) {
+			id = UUID.randomUUID().toString();
+		}
 	}
 
 	public RouteDefinition(String text) {

spring-cloud-gateway-core/src/test/java/org/springframework/cloud/gateway/route/RouteDefinitionDefaultIdTests.java

@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.gateway.route;
 
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -43,6 +45,16 @@ public class RouteDefinitionDefaultIdTests {
 	@Autowired
 	private GatewayProperties properties;
 
+	@BeforeClass
+	public static void before() {
+		System.setProperty("spring.cloud.gateway.route.generate-id", "true");
+	}
+
+	@AfterClass
+	public static void after() {
+		System.clearProperty("spring.cloud.gateway.route.generate-id");
+	}
+
 	@Test
 	public void testDefaultIdWorks() {
 		assertThat(properties.getRoutes()).hasSize(1);