An exploratory project for learning how to implement annotation-based feature toggles in Spring

How to use the feature toggle

1. Annotate the endpoint(s) in your controller with @FeatureToggle and define a name for it. Name could be reused so you could mark multiple related endpoints with the same feature name and be toggled at the same time.

   @RestController
   public class HelloWorldController {
       @FeatureToggle(name = "hello")
       @GetMapping("/hello")
       public String helloWorld() {
           return "Hello World";
       }
   }

2. Optional: List and toggle each feature in the application.yaml. When set to true, the endpoint will be available. Otherwise, it will return HTTP 404 when called.

   featuretoggle:
     features:
       hello: true
       # list of other features here    

Note: if the endpoints is annotated with @FeatureToggle but is not defined in the application.yaml, it will be disabled by default.

Future plans

• will try to change the featuretoggle.features in application.yaml into a list instead of a map to make it convenient to add/modify them as environment variables e.g. as environment variables of a K8s pod, which can be configured without rebuilding the application.
• will convert (or maybe create a new repo) this into a library instead of a Spring application