SpringCloud/spring-cloud-openfeign
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Added support for Spring Cloud CircuitBreaker

Browse Source 
fixes gh-279
This commit is contained in:
Marcin Grzejszczak
2020-12-15 15:52:14 +01:00
parent 89fb98daf7
commit e32b10b60f
13 changed files with 892 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
docs/src/main/asciidoc/_attributes.adoc
View File

@@ -14,3 +14,5 @@
:sc-ext: java
:project-full-name: Spring Cloud OpenFeign
:all: {asterisk}{asterisk}
:core_path: {project-root}/spring-cloud-openfeign-core

43
docs/src/main/asciidoc/spring-cloud-openfeign.adoc
View File

@@ -15,7 +15,7 @@ To use Feign create an interface and annotate it.
It has pluggable annotation support including Feign annotations and JAX-RS annotations.
Feign also supports pluggable encoders and decoders.
Spring Cloud adds support for Spring MVC annotations and for using the same `HttpMessageConverters` used by default in Spring Web.
Spring Cloud integrates Ribbon and Eureka, as well as Spring Cloud LoadBalancer to provide a load-balanced http client when using Feign.
Spring Cloud integrates Ribbon and Eureka, Spring Cloud CircuitBreaker, as well as Spring Cloud LoadBalancer to provide a load-balanced http client when using Feign.
[[netflix-feign-starter]]
=== How to Include Feign
@@ -55,7 +55,7 @@ public interface StoreClient {
}
----
In the `@FeignClient` annotation the String value ("stores" above) is an arbitrary client name, which is used to create either a https://github.com/Netflix/ribbon[Ribbon] load-balancer (see <<spring-cloud-ribbon,below for details of Ribbon support>>) or https://github.com/spring-cloud/spring-cloud-commons/blob/master/spring-cloud-commons/src/main/java/org/springframework/cloud/client/loadbalancer/reactive/ReactiveLoadBalancer.java[Spring Cloud LoadBalancer].
In the `@FeignClient` annotation the String value ("stores" above) is an arbitrary client name, which is used to create either a https://github.com/Netflix/ribbon[Ribbon] load-balancer (see <<spring-cloud-ribbon,below for details of Ribbon support>> and <<spring-cloud-circuitbreaker,below for details of Spring Cloud CircuitBreaker support>>) or https://github.com/spring-cloud/spring-cloud-commons/blob/master/spring-cloud-commons/src/main/java/org/springframework/cloud/client/loadbalancer/reactive/ReactiveLoadBalancer.java[Spring Cloud LoadBalancer].
You can also specify a URL using the `url` attribute
(absolute value or just a hostname). The name of the bean in the
application context is the fully qualified name of the interface.
@@ -119,6 +119,7 @@ Spring Cloud OpenFeign provides the following beans by default for feign (`BeanT
* `Logger` feignLogger: `Slf4jLogger`
* `Contract` feignContract: `SpringMvcContract`
* `Feign.Builder` feignBuilder: `HystrixFeign.Builder`
* `Feign.Builder` feignBuilder: `FeignCircuitBreaker.Builder`
* `Client` feignClient: if Ribbon is in the classpath and is enabled it is a `LoadBalancerFeignClient`, otherwise if Spring Cloud LoadBalancer is in the classpath, `FeignBlockingLoadBalancerClient` is used.
If none of them is in the classpath, the default feign client is used.
@@ -430,6 +431,44 @@ static class HystrixClientFallbackFactory implements FallbackFactory<HystrixClie
WARNING: There is a limitation with the implementation of fallbacks in Feign and how Hystrix fallbacks work. Fallbacks are currently not supported for methods that return `com.netflix.hystrix.HystrixCommand` and `rx.Observable`.
[[spring-cloud-feign-circuitbreaker]]
=== Feign Spring Cloud CircuitBreaker Support
If Spring Cloud CircuitBreaker is on the classpath and `feign.circuitbreaker.enabled=true`, Feign will wrap all methods with a circuit breaker.
To disable Spring Cloud CircuitBreaker 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();
}
}
----
The circuit breaker name follows this pattern `<feignClientName>_<calledMethod>`. When calling a `@FeignClient` with name `foo` and the called interface method is `bar` then the circuit breaker name will be `foo_bar`.
[[spring-cloud-feign-circuitbreaker-fallback]]
=== Feign Spring Cloud CircuitBreaker Fallbacks
Spring Cloud CircuitBreaker supports the notion of a fallback: a default code path that is executed when they circuit is open or there is an error. To enable fallbacks for a given `@FeignClient` set the `fallback` attribute to the class name that implements the fallback. You also need to declare your implementation as a Spring bean.
[source,java,indent=0]
----
include::{core_path}/src/test/java/org/springframework/cloud/openfeign/circuitbreaker/CirciutBreakerTests.java[tags=client_with_fallback, indent=0]
----
If one needs access to the cause that made the fallback trigger, one can use the `fallbackFactory` attribute inside `@FeignClient`.
[source,java,indent=0]
----
include::{core_path}/src/test/java/org/springframework/cloud/openfeign/circuitbreaker/CirciutBreakerTests.java[tags=client_with_fallback_factory, indent=0]
----
=== Feign and `@Primary`
When using Feign with Hystrix fallbacks, there are multiple beans in the `ApplicationContext` of the same type. This will cause `@Autowired` to not work because there isn't exactly one bean, or one marked as primary. To work around this, Spring Cloud OpenFeign marks all Feign instances as `@Primary`, so Spring Framework will know which bean to inject. In some cases, this may not be desirable. To turn off this behavior set the `primary` attribute of `@FeignClient` to false.