Allow Feign Hystrix support to be disabled.

fixes gh-717

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

@@ -806,6 +806,7 @@ Spring Cloud Netflix provides the following beans by default for feign (`BeanTyp
 * `Encoder` feignEncoder: `SpringEncoder`
 * `Logger` feignLogger: `Slf4jLogger`
 * `Contract` feignContract: `SpringMvcContract`
+* `Feign.Builder` feignBuilder: `HystrixFeign.Builder`
 
 Spring Cloud Netflix _does not_ provide the following beans by default for feign, but still looks up beans of these types from the application context to create the feign client:
 
@@ -837,6 +838,27 @@ This replaces the `SpringMvcContract` with `feign.Contract.Default` and adds a `
 
 Default configurations can be specified in the `@EnableFeignClients` attribute `defaultConfiguration` in a similar manner as described above. The difference is that this configuration will apply to _all_ feign clients.
 
+[[spring-cloud-feign-hystrix]]
+=== Feign Hystrix Support
+
+If Hystrix is on the classpath, by default Feign will wrap all methods with a circuit breaker. Returning a `com.netflix.hystrix.HystrixCommand` is also available. This lets you use reactive patterns (with a call to `.toObservable()` or `.observe()` or asynchronous use (with a call to `.queue()`).
+
+To disable Hystrix support for Feign, set `feign.hystrix.enabled=false`.
+
+To disable Hystrix support on a per-client basis create a vanilla `Feign.Builder` with the "prototype" scope, e.g.:
+
+[source,java,indent=0]
+----
+@Configuration
+public class FooConfiguration {
+    @Bean
+	@Scope("prototype")
+	public Feign.Builder feignBuilder() {
+		return Feign.builder();
+	}
+}
+----
+
 [[spring-cloud-feign-inheritance]]
 === Feign Inheritance Support
 

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/feign/FeignClientFactoryBean.java

@@ -75,7 +75,7 @@ class FeignClientFactoryBean implements FactoryBean<Object>, InitializingBean, A
 		}
 
 		// @formatter:off
-		Feign.Builder builder = HystrixFeign.builder()
+		Feign.Builder builder = get(factory, Feign.Builder.class)
 				// required values
 				.logger(logger)
 				.encoder(get(factory, Encoder.class))

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/feign/FeignClientsConfiguration.java

@@ -24,6 +24,7 @@ import org.springframework.beans.factory.ObjectFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.autoconfigure.web.HttpMessageConverters;
 import org.springframework.cloud.netflix.feign.support.ResponseEntityDecoder;
 import org.springframework.cloud.netflix.feign.support.SpringDecoder;
@@ -31,12 +32,17 @@ import org.springframework.cloud.netflix.feign.support.SpringEncoder;
 import org.springframework.cloud.netflix.feign.support.SpringMvcContract;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Scope;
+
+import com.netflix.hystrix.HystrixCommand;
 
 import feign.Client;
 import feign.Contract;
+import feign.Feign;
 import feign.codec.Decoder;
 import feign.codec.Encoder;
 import feign.httpclient.ApacheHttpClient;
+import feign.hystrix.HystrixFeign;
 
 /**
  * @author Dave Syer
@@ -68,6 +74,23 @@ public class FeignClientsConfiguration {
 		return new SpringMvcContract(parameterProcessors);
 	}
 
+	@Bean
+	@Scope("prototype")
+	@ConditionalOnMissingBean
+	@ConditionalOnClass(HystrixCommand.class)
+	@ConditionalOnProperty(name = "feign.hystrix.enabled", matchIfMissing = true)
+	public Feign.Builder feignHystrixBuilder() {
+		return HystrixFeign.builder();
+	}
+
+	@Bean
+	@Scope("prototype")
+	@ConditionalOnMissingBean
+	@ConditionalOnProperty(name = "feign.hystrix.enabled", matchIfMissing = false, havingValue = "false")
+	public Feign.Builder feignBuilder() {
+		return Feign.builder();
+	}
+
 	@Configuration
 	@ConditionalOnClass(ApacheHttpClient.class)
 	protected static class HttpClientConfiguration {

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/feign/EnableFeignClientsTests.java

@@ -17,9 +17,11 @@
 package org.springframework.cloud.netflix.feign;
 
 import feign.Contract;
+import feign.Feign;
 import feign.Logger;
 import feign.codec.Decoder;
 import feign.codec.Encoder;
+import feign.hystrix.HystrixFeign;
 import feign.slf4j.Slf4jLogger;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -70,6 +72,11 @@ public class EnableFeignClientsTests {
 		SpringMvcContract.class.cast(this.factory.getInstance("foo", Contract.class));
 	}
 
+	@Test
+	public void builderDefaultCorrect() {
+		HystrixFeign.Builder.class.cast(this.factory.getInstance("foo", Feign.Builder.class));
+	}
+
 	@Configuration
 	@Import({ PropertyPlaceholderAutoConfiguration.class,
 			ArchaiusAutoConfiguration.class, FeignAutoConfiguration.class })

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/feign/FeignClientOverrideDefaultsTests.java

@@ -19,6 +19,7 @@ package org.springframework.cloud.netflix.feign;
 import static org.junit.Assert.*;
 
 import feign.Contract;
+import feign.Feign;
 import feign.Logger;
 import feign.Request;
 import feign.RequestInterceptor;
@@ -27,6 +28,7 @@ import feign.auth.BasicAuthRequestInterceptor;
 import feign.codec.Decoder;
 import feign.codec.Encoder;
 import feign.codec.ErrorDecoder;
+import feign.hystrix.HystrixFeign;
 import feign.slf4j.Slf4jLogger;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -97,6 +99,12 @@ public class FeignClientOverrideDefaultsTests {
 		ErrorDecoder.Default.class.cast(factory.getInstance("bar", ErrorDecoder.class));
 	}
 
+	@Test
+	public void overrideBuilder() {
+		Feign.Builder.class.cast(factory.getInstance("foo", Feign.Builder.class));
+		HystrixFeign.Builder.class.cast(factory.getInstance("bar", Feign.Builder.class));
+	}
+
 	@Test
 	public void overrideRequestOptions() {
 		assertNull(factory.getInstance("foo", Request.Options.class));
@@ -145,6 +153,11 @@ public class FeignClientOverrideDefaultsTests {
 		public Contract feignContract() {
 			return new Contract.Default();
 		}
+
+		@Bean
+		public Feign.Builder feignBuilder() {
+			return Feign.builder();
+		}
 	}
 
 	@FeignClient(value = "bar", configuration = BarConfiguration.class)

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/feign/valid/FeignHttpClientTests.java

@@ -62,7 +62,8 @@ import lombok.NoArgsConstructor;
 @RunWith(SpringJUnit4ClassRunner.class)
 @SpringApplicationConfiguration(classes = FeignHttpClientTests.Application.class)
 @WebAppConfiguration
-@IntegrationTest({ "server.port=0", "spring.application.name=feignclienttest" })
+@IntegrationTest({ "server.port=0", "spring.application.name=feignclienttest",
+		"feign.hystrix.enabled=false" })
 @DirtiesContext
 public class FeignHttpClientTests {