Change FeignClient url at runtime

Question

Having Feign client as presented:

@FeignClient(name = "storeClient", url = "${feign.url}")
public interface StoreClient {
    //..
}

Is is possible to make use of Spring Cloud capabilities of environment changes to change the Feign url at runtime? (Changing the feign.url property and invoking /refresh endpoint)

Answer 1

As a possible solution - RequestInterceptor could be introduced in order to set URL in RequestTemplate from a property defined in the RefreshScope.

To implement this approach you should do the following:

1. Define ConfigurationProperties Component in the RefreshScope

   @Component
   @RefreshScope
   @ConfigurationProperties("storeclient")
   public class StoreClientProperties {
       private String url;
       ...
   }
   

2. Specify default URL for the client in the application.yml

   storeclient
       url: https://someurl
   

3. Define RequestInterceptor that will switch URL

   @Configuration
   public class StoreClientConfiguration {
   
       @Autowired
       private StoreClientProperties storeClientProperties;
   
       @Bean
       public RequestInterceptor urlInterceptor() {
           return template -> template.insert(0, storeClientProperties.getUrl());
       }
   
   }
   

4. Use some placeholder in your FeignClient definition for the URL, because it will not be used

   @FeignClient(name = "storeClient", url = "NOT_USED")
   public interface StoreClient {
       //..
   }
   

Now storeclient.url can be refreshed and the URL defined will be used in RequestTemplate to sent http request.