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Fix gh 177 add sc loadbalancer support (#239)

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* Add FeignBlockingLoadBalancerClient, configurations for default, apache
httpclient and okhttp setup. Add autoconfiguration. Init fix for gh-177.

* Fix SC loadbalancer dependencies.

* Fix generating Feign response when instance not found.

* Fix configuration.

* Add tests for FeignBlockingLoadBalancerClient and FeignLoadBalancerAutoConfiguration.

* Fix checkstyle and formatting.

* Refactor, add docs and javadocs.

* Fix author name.

* Fix docs after code review.
This commit is contained in:
Olga Maciaszek-Sharma
2019-11-06 19:06:39 +01:00
committed by GitHub
parent bc10583bf3
commit f661105e63
16 changed files with 797 additions and 151 deletions
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25
docs/src/main/asciidoc/spring-cloud-openfeign.adoc
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@@ -9,7 +9,13 @@ include::intro.adoc[]
[[spring-cloud-feign]]
== Declarative REST Client: Feign
https://github.com/Netflix/feign[Feign] is a declarative web service client. It makes writing web service clients easier. 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 to provide a load balanced http client when using Feign.
https://github.com/OpenFeign/feign[Feign] is a declarative web service client.
It makes writing web service clients easier.
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.
[[netflix-feign-starter]]
=== How to Include Feign
@@ -46,22 +52,24 @@ public interface StoreClient {
}
----
In the `@FeignClient` annotation the String value ("stores" above) is
an arbitrary client name, which is used to create a Ribbon load
balancer (see <<spring-cloud-ribbon,below for details of Ribbon
support>>). You can also specify a URL using the `url` attribute
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].
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.
To specify your own alias value you can use the `qualifier` value
of the `@FeignClient` annotation.
The Ribbon client above will want to discover the physical addresses
The load-balancer client above will want to discover the physical addresses
for the "stores" service. If your application is a Eureka client then
it will resolve the service in the Eureka service registry. If you
don't want to use Eureka, you can simply configure a list of servers
in your external configuration (see
<<spring-cloud-ribbon-without-eureka,above for example>>).
WARNING: In order to maintain backward compatibility, is used as the default load-balancer implementation.
However, Spring Cloud Netflix Ribbon is now in maintenance mode, so we recommend using Spring Cloud LoadBalancer instead.
To do this, set the value of `spring.cloud.loadbalancer.ribbon.enabled` to `false`.
[[spring-cloud-feign-overriding-defaults]]
=== Overriding Feign Defaults
@@ -109,7 +117,10 @@ Spring Cloud Netflix provides the following beans by default for feign (`BeanTyp
* `Logger` feignLogger: `Slf4jLogger`
* `Contract` feignContract: `SpringMvcContract`
* `Feign.Builder` feignBuilder: `HystrixFeign.Builder`
* `Client` feignClient: if Ribbon is enabled it is a `LoadBalancerFeignClient`, otherwise the default feign client is used.
* `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.
NOTE: `spring-cloud-starter-openfeign` contains both `spring-cloud-starter-netflix-ribbon` and `spring-cloud-starter-loadbalancer`.
The OkHttpClient and ApacheHttpClient feign clients can be used by setting `feign.okhttp.enabled` or `feign.httpclient.enabled` to `true`, respectively, and having them on the classpath.
You can customize the HTTP client used by providing a bean of either `org.apache.http.impl.client.CloseableHttpClient` when using Apache or `okhttp3.OkHttpClient` when using OK HTTP.