java - Spring cloud stream kafka pause/resume binders

Question

We are using spring cloude stream 2.0 & Kafka as a message broker.
We've implemented a circuit breaker which stops the Application context, for cases where the target system (DB or 3rd party API) is unavilable, as suggested here: Stop Spring Cloud Stream @StreamListener from listening when target system is down

Now in spring cloud stream 2.0 there is a way to manage the lifecycle of binder using actuator: Binding visualization and control

Is it possible to control the binder lifecycle from the code, means in case target server is down, to pause the binder, and when it's up, to resume?

Answer 1

Sorry, I misread your question.

You can auto wire the BindingsEndpoint but, unfortunately, its State enum is private so you can't call changeState() programmatically.

I have opened an issue for this.

EDIT

You can do it with reflection, but it's a bit ugly...

@SpringBootApplication
@EnableBinding(Sink.class)
public class So53476384Application {

    public static void main(String[] args) {
        SpringApplication.run(So53476384Application.class, args);
    }

    @Autowired
    BindingsEndpoint binding;

    @Bean
    public ApplicationRunner runner() {
        return args -> {
            Class<?> clazz = ClassUtils.forName("org.springframework.cloud.stream.endpoint.BindingsEndpoint$State",
                    So53476384Application.class.getClassLoader());
            ReflectionUtils.doWithMethods(BindingsEndpoint.class, method -> {
                try {
                    method.invoke(this.binding, "input", clazz.getEnumConstants()[2]); // PAUSE
                }
                catch (InvocationTargetException e) {
                    e.printStackTrace();
                }
            }, method -> method.getName().equals("changeState"));
        };
    }

    @StreamListener(Sink.INPUT)
    public void listen(String in) {

    }

}