Annotations for feature flipping REST end points

Question

I have spring controller with several (REST) endpoints. I want to bring up multiple instances of this controller where each instance would have few endpoints selectively enabled/disabled.

Based on my reading so far, togglz provides feature flipping, but it doesnt enable/disable the REST endpoints (togglz provides API so that caller code can check if a feature is enabled); ff4j seems to be another alternative, but it was not very obvious from the documentation if it can enable/disable REST end points

I read the thread Feature Toggling Java Annotations but it is a longer implementation. Is there any package that I can use to specify the endpoints that need to be enabled/disabled in a configuration file and use annotation on REST endpoints to disable/enable them (this way the logic in my method stays untouched and minimizes the testing)

Answer 1

A class with the @Bean or @Component will be loaded by spring on startup through the bean visitor mechanism. To exclude this bean from the Spring context at startup you can create a BeanPostProcessor(here) and check for dedicated annotation BUT as far as I understand, you cannot put the bean back to the context at runtime.

As a consequence, you must make this bean 'intelligent' to perform the correct operation/mock (or send 503 HTTP code) when requests come in.

FF4j can indeed help you implementing this behaviour but not with a single annotation on top of your REST Controller. What you could do :

• Create an interface, annotate the interface with the dedicated FF4J annotation
• Create 2 implementations of the interface, each time with a different name
• Use FF4J to choose an implementation or another at runtime.

Here some code snippet to get the idea :

public interface GreetingService {
  @Flip(name = "theFeatureIDToToggle", alterBean = "greeting.french")
  String sayHello(String name);
}

@Component("greeting.french")
public class GreetingServiceFrenchImpl implements GreetingService {
    public String sayHello(String name) {return "Bonjour " + name;
}

@Component("greeting.english")
public class GreetingServiceEnglishImpl implements GreetingService {
    public String sayHello(String name) {return "Hello " + name;
}

//... import
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext-ff4j-aop-test.xml")
public class FeatureAdvisorTest {

   @Autowired
   private FF4j ff4j;

   @Autowired
   @Qualifier("greeting.english")
   private GreetingService greeting

   @Test
   public void testAnnotatedFlipping_with_alterBean() {
      ff4j.disable("theFeatureIDToToggle");
      Assert.assertTrue(greeting.sayHello("CLU").startsWith("Hello"));

      ff4j.enable("theFeatureIDToToggle");
      Assert.assertTrue(greeting.sayHello("CLU").startsWith("Bonjour"));
   }
}

You can toggle a single method or the whole class, as you wish all samples are available here.