How to determine which default http client was injected by Spring container for @FeignClient?

Question

I am using @FeignClient annotation. I want to know which httpclient was injected by Spring when i am running my application.

For example, 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.

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@FeignClient(name = "service", path = "/api/v1", configuration = ServiceConfiguration.class)
public interface ServiceClient {

    @RequestMapping(method = RequestMethod.GET, value = "/test/{param1}", consumes = MediaType.APPLICATION_JSON_VALUE)
    String test(@PathVariable("param1") String param);
}

I am not sure now which of these client is being injected since my application is complex with multiple httpclient libraries in the classpath.

Is there a way that i can monitor it ?

I enabled JMX and tried to view the jconsole Mbeans and there was no information about httpclients.

Answer 1

It's impossible to tell without seeing your Spring setup, especially if your application is complex like you said.

Since you are using Spring annotations to declare your @FeignClient you most likely are depending on spring-cloud-netflix-core. If you are enabling defaults with @EnableFeignClients take a look at FeignAutoConfiguration class. This class registers the actual HTTP client bean. If you add both feign.httpclient.enabled and feign.okhttp.enabled properties (which IMO is a weird setup) try debugging FeignAutoConfiguration to see which Client feignClient() bean will be registered in the Spring context.

Alternatively enable wire logging in all HTTP client libraries and see which one actually executes the request based on logs.

Answer 2

According to previous answer, now I see this row in FeignAutoConfiguration.java

@ConditionalOnProperty(value = "feign.httpclient.enabled", matchIfMissing = true)

So simple answer would be Apache Client by default if you don't add any properties

Answer 3

you can add breakpoint in feign.Client#execute and debug your program