SpringCloud Config @RefreshScope Anotasyonu

Giriş

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import org.springframework.cloud.context.config.annotation.RefreshScope;

@RefreshScope anotasyonunu açıklaması şöyle

When this annotation is applied to a Spring component (i.e., a @Component, @Service, @RestController, etc.), the component is re-created when a configuration refresh occurs, in this case giving an updated value for ${hello.message}.

You can refresh an application’s configuration by including the Spring Boot Actuator dependency, exposing the /actuator/refresh endpoint, and sending an empty POST request

Don’t use @RefreshScope in controllers

Açıklaması şöyle

Now, what about using @RefreshScope in controllers? While it's technically possible to use @RefreshScope in controllers, it's generally not recommended. Controllers are typically responsible for handling incoming requests and generating responses, and their behavior shouldn't be affected by changes to configuration settings. In addition, refreshing a controller could result in requests being dropped or delayed, which could have a negative impact on the user experience.

Instead, it’s better to use @RefreshScope with beans that are responsible for handling configuration settings, such as @ConfigurationProperties or @Value beans. By using @RefreshScope with these beans, you can ensure that changes to the configuration are applied across the entire application without having to restart it.

Örnek 

Şöyle yaparız. Burada Config Server'dan okunacak değer @Vaue ile çekiliyor.

@RefreshScope
@RestController
@RequestMapping("/secure")
public static class SecureController {
  @Value("${hello.message}")
  private String helloMessage;
  
  @GetMapping
  public String secure(Principal principal) {
    return helloMessage;
  }
}

Örnek

Şöyle yaparız. Burada @RefreshScope ile yeni konfigürasyonun okunabileceği belirtiliyor. Konfigürasyon verisi sürekli env.getProperty() şeklinde alınıyor.

import org.springframework.core.env.Environment;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.ui.Model;

@RefreshScope
@RestController
public class HelloController {
  @Autowired
  private Environment env;
  
  @GetMapping("/hello")
  public ResponseEntity<String> getHello(Model model) {   
    return new ResponseEntity<String>( env.getProperty("message"), HttpStatus.OK);
  }
}

Eğer Config Server'da bir şey değişirse Client uygulamayı ayarları tekrar okuması için  tetiklemek gerekir. Şöyle yaparız

http://localhost:8080/actuator/refresh