@FeignClient with top level @RequestMapping annotation is also registered as Spring MVC handler

[jmnarloch]

This is follow up to the discussion from this issue: #457

Generally the problem is that: when you annotate an @FeignClient interface with @RequestMapping annotation the handler will be also registered within Spring MVC.

Example:

@FeignClient("localapp")

@RequestMapping(value = "/users")

public interface UsersClient extends CrudClient<User> {


}

In this test case: jmnarloch@2d24bf6 this acctually causes the test to fail with error:

Caused by: java.lang.IllegalStateException: Ambiguous mapping. Cannot map 'feignHttpClientTests$UserClient' method 
public abstract T org.springframework.cloud.netflix.feign.valid.FeignHttpClientTests$CrudClient.get(long)
to {[/users/{id}],methods=[GET]}: There is already 'feignHttpClientTests.Application' bean method
public java.lang.Object org.springframework.cloud.netflix.feign.valid.FeignHttpClientTests$Application.get(long) mapped.
    at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping$MappingRegistry.assertUniqueMethodMapping(AbstractHandlerMethodMapping.java:565)
    at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping$MappingRegistry.register(AbstractHandlerMethodMapping.java:529)
    at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.registerHandlerMethod(AbstractHandlerMethodMapping.java:252)
    at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.detectHandlerMethods(AbstractHandlerMethodMapping.java:223)
    at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.initHandlerMethods(AbstractHandlerMethodMapping.java:183)
    at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.afterPropertiesSet(AbstractHandlerMethodMapping.java:164)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.afterPropertiesSet(RequestMappingHandlerMapping.java:134)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1637)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1574)
    ... 44 more

Due to duplicated Spring MVC - FeignClient mappings, but this how I found this issue.

Removing the top @RequestMapping fixes the tests, but disallows some advances usages like interface inheritance and path overriding.

[jmnarloch]

So is there some neat way to hide the @RequestMapping annotation on the interface type?
I guess that it's being exposed through FeignClientFactoryBean#getObjectType method.

[dsyer]

There's no way to hide it other than not be in a web application. Or I guess put it in a child context with no handler mappings. I don't expect this will be explicitly supportable in the framework, but if you try it and it works it might be good to share your experience here.

[spencergibb]

Closing, this would need to change in the framework.

[succour]

Does it have any new progress?

[spencergibb]

@succour this issue is closed and we cannot fix it as this how spring framework works.

[joevalerio]

could we not get around this by just extending the EnableWebMvcConfiguration to ignore classes annotated with @RequestMapping AND @FeignClient? Something like this? It appears to be working.

@Configuration
public class WebConfiguration extends EnableWebMvcConfiguration {

    @Override
    protected RequestMappingHandlerMapping createRequestMappingHandlerMapping() {
    RequestMappingHandlerMapping mapping = new RequestMappingHandlerMapping(){
            @Override
            protected boolean isHandler(Class<?> beanType) {
                return super.isHandler(beanType) && (AnnotationUtils.findAnnotation(beanType, FeignClient.class) == null);
            }
    };
    return mapping;
    }
}

[dsyer]

That's a decent workaround. I'm not sure I want that code to be in Spring Cloud though. IMO Spring MVC should not consider a bean without a @Controller annotation to be a handler. You'd have to take that up in JIRA though.

[joevalerio]

I agree this should not exist in spring-cloud but only as a specific workaround for this issue. I also agree with your other point about @controller but that ship has sail and it would be a major breaking change to revert that now. In the mean time, we need to manage clients. IMO they are easier to maintain with the @RequestMapping annotations, and applying it at the Class level reduces the need for each method's @RequestMapping to set its consumes/produces property, making the file much easier to read and maintain.

Long term, it would be great if we could delegate the isHandler method to a Bean, then spring-cloud-netflix could supply a version that takes @FeignClient into consideration to avoid the bindings.

[cforce]

We have worked around it by using anotation on method only

joevalerio notifications@github.com schrieb am Mi., 20. Juli 2016, 18:18:

I agree this should not exist in spring-cloud but only as a specific
workaround for this issue. I also agree with your other point about
@controller https://github.com/Controller but that ship has sail and it
would be a major breaking change to revert that now. In the mean time, we
need to manage clients. IMO they are easier to maintain with the
@RequestMapping annotations, and applying it at the Class level reduces the
need for each method's @ReqeustMapping to set its consumes/produces
property, making the file much easier to read and maintain.

Long term, it would be great if we could delegate the isHandler method to
a Bean, then spring-cloud-netflix could supply a version that does take the
@FeignClient into consideration to avoid the bindings.

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[kadaan]

What about doing:

@Configuration
@ConditionalOnClass({Feign.class})
public class FeignMappingDefaultConfiguration {
    @Bean
    public WebMvcRegistrations feignWebRegistrations() {
        return new WebMvcRegistrationsAdapter() {
            @Override
            public RequestMappingHandlerMapping getRequestMappingHandlerMapping() {
                return new FeignFilterRequestMappingHandlerMapping();
            }
        };
    }

    private static class FeignFilterRequestMappingHandlerMapping extends RequestMappingHandlerMapping {
        @Override
        protected boolean isHandler(Class<?> beanType) {
            return super.isHandler(beanType) && (AnnotationUtils.findAnnotation(beanType, FeignClient.class) == null);
        }
    }
}

[SympathyForTheDev]

@kadaan thank for your code, it's working great :)

[zhijun714]

@kadaan thank for your code.

[mengxiangrui007]

@kadaan thank for your code.

[chuguoren]

@kadaan thank for your code.

[qiujiayu]

@Configuration
@ConditionalOnClass({ Feign.class })
public class FeignMappingDefaultConfiguration {
    @Bean
    public WebMvcRegistrations feignWebRegistrations() {
        return new WebMvcRegistrationsAdapter() {
            @Override
            public RequestMappingHandlerMapping getRequestMappingHandlerMapping() {
                return new FeignFilterRequestMappingHandlerMapping();
            }
        };
    }

    @Slf4j
    private static class FeignFilterRequestMappingHandlerMapping extends RequestMappingHandlerMapping {
        @Override
        protected boolean isHandler(Class<?> beanType) {
            return super.isHandler(beanType) && !beanType.isInterface();
        }
    }
}

@kadaan

[ARadauer]

In my opinion this is a major security issue in spring. My application is exposing services which I call internally just because the team of the other service annotated their interfaces with @ RequestMapping on top level.
This is not what I would expect. If I want a Controller to behave like a Controller it should be annotated as Controller.

        protected boolean isHandler(Class<?> beanType) {
            return (AnnotatedElementUtils.hasAnnotation(beanType, Controller.class));
        }
  

[dsyer]

I guess you need to open an issue in the Spring JIRA for that?

[asgh]

Can you maybe throw an error if a FeignClient also has a RequestMapping? This would at least help people who get bitten by this.

[sparqueur]

Workaround provided by @kadaan works well when running the server but fails in Spring boot tests (FeignFilterRequestMappingHandlerMapping.isHandler is not called).
Any clue ?

[Hronom]

What the progress on this?
Why not just add rule to the Spring MVC that will register handler only if it annotated by @Controller or @RestController? Looks very oblivious and will not bring to the Spring MVC any additional dependency.

[spencergibb]

That's in spring Framework and not handled here, hence it was closed. Open in issue in http://jira.spring.io if you'd like

[Hronom]

@spencergibb Was able to reproduce this, will create issue for this on jira. Reproducible at Greenwich.RC2 and Spring Boot 2.1.1.RELEASE.

Here is my test project for this https://github.com/Hronom/test-shared-mapping-interface

[Hronom]

Done https://jira.spring.io/browse/SPR-17622

[storm-coding]

Why not use path. Such as @FeignClient(name="localapp", path="users")

[storm-coding]

@jmnarloch