Make webflux optional

pom.xml

@@ -91,6 +91,12 @@
 					</exclusion>
 				</exclusions>
 			</dependency>
+			<dependency>
+				<groupId>org.springframework.cloud</groupId>
+				<artifactId>spring-cloud-test-support</artifactId>
+				<scope>test</scope>
+				<version>${spring-cloud-commons.version}</version>
+			</dependency>
 			<dependency>
 				<groupId>org.springframework.cloud</groupId>
 				<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>

spring-cloud-gateway-core/pom.xml

@@ -76,6 +76,11 @@
 			<artifactId>spring-boot-starter-test</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-test-support</artifactId>
+			<scope>test</scope>
+		</dependency>
 		<dependency>
 			<groupId>io.projectreactor</groupId>
 			<artifactId>reactor-test</artifactId>

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java

@@ -104,7 +104,8 @@ import rx.RxReactiveStreams;
 @ConditionalOnProperty(name = "spring.cloud.gateway.enabled", matchIfMissing = true)
 @EnableConfigurationProperties
 @AutoConfigureBefore(HttpHandlerAutoConfiguration.class)
-@AutoConfigureAfter(GatewayLoadBalancerClientAutoConfiguration.class)
+@AutoConfigureAfter({GatewayLoadBalancerClientAutoConfiguration.class, GatewayClassPathWarningAutoConfiguration.class})
+@ConditionalOnClass(DispatcherHandler.class)
 public class GatewayAutoConfiguration {
 
 	@Configuration

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/config/GatewayClassPathWarningAutoConfiguration.java

@@ -2,18 +2,37 @@ package org.springframework.cloud.gateway.config;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.springframework.boot.autoconfigure.AutoConfigureBefore;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingClass;
 import org.springframework.context.annotation.Configuration;
 
 @Configuration
-@ConditionalOnClass(name = "org.springframework.web.servlet.DispatcherServlet")
+@AutoConfigureBefore(GatewayAutoConfiguration.class)
 public class GatewayClassPathWarningAutoConfiguration {
 
 	private static final Log log = LogFactory.getLog(GatewayClassPathWarningAutoConfiguration.class);
 	private static final String BORDER = "\n\n**********************************************************\n\n";
 
-	public GatewayClassPathWarningAutoConfiguration() {
-		log.warn(BORDER+"Spring MVC found on classpath, which is incompatible with Spring Cloud Gateway at this time. "+
-			"Please remove spring-boot-starter-web dependency."+BORDER);
+	@Configuration
+	@ConditionalOnClass(name = "org.springframework.web.servlet.DispatcherServlet")
+	protected static class SpringMvcFoundOnClasspathConfiguration {
+
+		public SpringMvcFoundOnClasspathConfiguration() {
+			log.warn(BORDER+"Spring MVC found on classpath, which is incompatible with Spring Cloud Gateway at this time. "+
+					"Please remove spring-boot-starter-web dependency."+BORDER);
+		}
+
+	}
+
+	@Configuration
+	@ConditionalOnMissingClass("org.springframework.web.reactive.DispatcherHandler")
+	protected static class WebfluxMissingFromClasspathConfiguration {
+
+		public WebfluxMissingFromClasspathConfiguration() {
+			log.warn(BORDER+"Spring Webflux is missing from the classpath, which is required for Spring Cloud Gateway at this time. "+
+					"Please add spring-boot-starter-webflux dependency."+BORDER);
+		}
+
 	}
 }

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/config/GatewayLoadBalancerClientAutoConfiguration.java

@@ -25,12 +25,13 @@ import org.springframework.cloud.gateway.filter.LoadBalancerClientFilter;
 import org.springframework.cloud.netflix.ribbon.RibbonAutoConfiguration;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.web.reactive.DispatcherHandler;
 
 /**
  * @author Spencer Gibb
  */
 @Configuration
-@ConditionalOnClass({LoadBalancerClient.class, RibbonAutoConfiguration.class})
+@ConditionalOnClass({LoadBalancerClient.class, RibbonAutoConfiguration.class, DispatcherHandler.class})
 @AutoConfigureAfter(RibbonAutoConfiguration.class)
 public class GatewayLoadBalancerClientAutoConfiguration {
 

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/config/GatewayRedisAutoConfiguration.java

@@ -22,12 +22,13 @@ import org.springframework.data.redis.serializer.RedisSerializationContext;
 import org.springframework.data.redis.serializer.RedisSerializer;
 import org.springframework.data.redis.serializer.StringRedisSerializer;
 import org.springframework.scripting.support.ResourceScriptSource;
+import org.springframework.web.reactive.DispatcherHandler;
 
 @Configuration
 @AutoConfigureAfter(RedisReactiveAutoConfiguration.class)
 @AutoConfigureBefore(GatewayAutoConfiguration.class)
 @ConditionalOnBean(ReactiveRedisTemplate.class)
-@ConditionalOnClass(RedisTemplate.class)
+@ConditionalOnClass({RedisTemplate.class, DispatcherHandler.class})
 class GatewayRedisAutoConfiguration {
 
 	@Bean

spring-cloud-gateway-core/src/main/resources/META-INF/spring.factories

@@ -1,6 +1,6 @@
 # Auto Configure
 org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
-org.springframework.cloud.gateway.config.GatewayAutoConfiguration,\
 org.springframework.cloud.gateway.config.GatewayClassPathWarningAutoConfiguration,\
+org.springframework.cloud.gateway.config.GatewayAutoConfiguration,\
 org.springframework.cloud.gateway.config.GatewayLoadBalancerClientAutoConfiguration,\
 org.springframework.cloud.gateway.config.GatewayRedisAutoConfiguration

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

@@ -0,0 +1,40 @@
+/*
+ * 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.test;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.SpringBootConfiguration;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.cloud.test.ClassPathExclusions;
+import org.springframework.cloud.test.ModifiedClassPathRunner;
+
+@RunWith(ModifiedClassPathRunner.class)
+@ClassPathExclusions({"spring-webflux-*.jar"})
+public class WebfluxNotIncludedTests {
+
+	@Test
+	public void noWebfluxWorks() {
+		new SpringApplication(Config.class).run();
+	}
+
+	@SpringBootConfiguration
+	@EnableAutoConfiguration
+	public static class Config {}
+}

spring-cloud-starter-gateway/pom.xml

@@ -24,9 +24,5 @@
 			<groupId>org.springframework.cloud</groupId>
 			<artifactId>spring-cloud-gateway-core</artifactId>
 		</dependency>
-		<dependency>
-			<groupId>org.springframework.boot</groupId>
-			<artifactId>spring-boot-starter-webflux</artifactId>
-		</dependency>
 	</dependencies>
 </project>