Adds sample Throttle WebFilter

spring-cloud-gateway-sample/pom.xml

@@ -34,6 +34,11 @@
 			<groupId>org.springframework.cloud</groupId>
 			<artifactId>spring-cloud-starter-gateway</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>org.isomorphism</groupId>
+			<artifactId>token-bucket</artifactId>
+			<version>1.7</version>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-test</artifactId>

spring-cloud-gateway-sample/src/main/java/org/springframework/cloud/gateway/sample/GatewaySampleApplication.java

@@ -28,6 +28,7 @@ import org.springframework.context.annotation.Bean;
 import static org.springframework.cloud.gateway.filter.factory.WebFilterFactories.addResponseHeader;
 import static org.springframework.cloud.gateway.handler.predicate.RoutePredicates.host;
 import static org.springframework.cloud.gateway.handler.predicate.RoutePredicates.path;
+import static org.springframework.tuple.TupleBuilder.tuple;
 
 /**
  * @author Spencer Gibb
@@ -38,7 +39,7 @@ import static org.springframework.cloud.gateway.handler.predicate.RoutePredicate
 public class GatewaySampleApplication {
 
 	@Bean
-	public RouteLocator customRouteLocator() {
+	public RouteLocator customRouteLocator(ThrottleWebFilterFactory throttle) {
 		return Routes.locator()
 				.route("test")
 					.uri("http://httpbin.org:80")
@@ -50,9 +51,23 @@ public class GatewaySampleApplication {
 					.predicate(path("/image/webp"))
 					.add(addResponseHeader("X-AnotherHeader", "baz"))
 					.and()
+				.route("test3")
+					.order(-1)
+					.uri("http://httpbin.org:80")
+					.predicate(host("**.throttle.org").and(path("/get")))
+					.add(throttle.apply(tuple().of("capacity", 1,
+							"refillTokens", 1,
+							"refillPeriod", 10,
+							"refillUnit", "SECONDS")))
+					.and()
 				.build();
 	}
 
+	@Bean
+	public ThrottleWebFilterFactory throttleWebFilterFactory() {
+		return new ThrottleWebFilterFactory();
+	}
+
 	public static void main(String[] args) {
 		SpringApplication.run(GatewaySampleApplication.class, args);
 	}

spring-cloud-gateway-sample/src/main/java/org/springframework/cloud/gateway/sample/ThrottleWebFilterFactory.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2013-2017 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
+ *
+ *      http://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.sample;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.isomorphism.util.TokenBucket;
+import org.isomorphism.util.TokenBuckets;
+import org.springframework.cloud.gateway.filter.factory.WebFilterFactory;
+import org.springframework.http.HttpStatus;
+import org.springframework.tuple.Tuple;
+import org.springframework.web.server.WebFilter;
+
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Sample throttling filter.
+ * See https://github.com/bbeck/token-bucket
+ */
+public class ThrottleWebFilterFactory implements WebFilterFactory {
+	private Log log = LogFactory.getLog(getClass());
+
+	@Override
+	public WebFilter apply(Tuple args) {
+		int capacity = args.getInt("capacity");
+		int refillTokens = args.getInt("refillTokens");
+		int refillPeriod = args.getInt("refillPeriod");
+		TimeUnit refillUnit = TimeUnit.valueOf(args.getString("refillUnit"));
+
+		final TokenBucket tokenBucket = TokenBuckets.builder()
+				.withCapacity(capacity)
+				.withFixedIntervalRefillStrategy(refillTokens, refillPeriod, refillUnit)
+				.build();
+
+		return (exchange, chain) -> {
+			log.debug("TokenBucket capacity: " + tokenBucket.getCapacity());
+			boolean consumed = tokenBucket.tryConsume();
+			if (consumed) {
+				return chain.filter(exchange);
+			}
+			exchange.getResponse().setStatusCode(HttpStatus.TOO_MANY_REQUESTS);
+			return exchange.getResponse().setComplete();
+		};
+	}
+}