How to configure dynamic properties while using spring boot?

Question

I'm planning to use Spring Boot for my assignment. Its a typical server application with connection to database. I know I can use Spring Configuration to externalize my properties e.g. db connection details. But I also have other dynamic properties which needs be updated at runtime. e.g. flippers/feature flags. Certain features of my application needs to be controlled dynamically e.g. imagine a property like app.cool-feature.enable=true and then after a while the same feature would be turned off by app.cool-feature.enable=false

Any suggestions what is the best practice around ingesting such dynamic behavior at runtime? I can think of following options to trigger the change...

• Send a JMS message to server instance with above property change
• Call an exposed API endpoint on the server instance e.g. POST http://myapp/admin/config/update { "config": { "app.cool-feature.enable": true } }

I know I can write the my own custom code implementing this (it would be for the 3rd time) but just wondering if there is already standard way/common practice around dynamic property configurations that I'm not aware of. Also it would be great if it can work with other solutions like Apache ZooKeeper, coreos etcd, Netflix curator etc and have close integration with Spring.

Thoughts?

Answer 1

If you are using Spring boot have a look on @ConfigurationProperties. You will be required to provide a Bean to access your properties. Therefore original values of the properties can be changed during execution since they are regular properties of a bean.

In your case for example:

@Component
@ConfigurationProperties
public class JmsProperties {

    private String url = "vm://localhost" (let's suppose you use ActiveMQ);

    public String getUrl()...
    public void setUrl(String value)...

}

And then inject this bean in you JMS message listener.

Of course if you use JMS and Spring boot, with autoconfiguration you already have Properties class...