如何在不重新启动应用程序的情况下在 PCF 中运行的 spring 引导应用程序中加载更改的环境变量？

Question

We have a spring boot application running in PCF and it reads the PCF environment variables(CF_INSTANCE_INDEX, CF_INSTANCE_ADDR,..) from an application. Based on those variables, we are trying to implement the logic for a scheduler. While running this scheduler, these variables' values could have changed. Is there a way to refresh/reload bean that have env values during runtime?

we used @RefreshScope annotation on config properties bean.

@Configuration
@RefreshScope
public class PcfEnvProperties{

@Value("${CF_INSTANCE_INDEX}")
private int intanceIndex;

@Value("${CF_INSTANCE_ADDR}")
private String intanceAddr;

...
}

and refresh using

context.getBean(RefreshScope.class).refresh("PcfEnvProperties");
PcfEnvProperties pcfEnv = context.getBean(PcfEnvProperties.class);

But It is not loading the recently changed env variable into running application. Any ideas on how to accomplish this?

Answer 1

You can use Spring Cloud Config Server in combination with Spring Actuator to expose an endpoint in your service that will refresh the application's properties on the fly. You could set up your scheduler to hit this endpoint on a timer or as needed.

Here is one tutorial I found that seems pretty straightforward: https://jeroenbellen.com/manage-and-reload-spring-application-properties-on-the-fly/

You may have to play with the setup depending on how your platform is configured, but I believe it should do what you're wanting. We have deployed many java web services on our PCF platform using this actuator/config server approach, and we can just make a call to the refresh endpoint and it successfully pulls in (and overwrites when necessary) the new properties and values from the config server. Also you can pull out a list of the property names and values that changed from the response.

I'm not familiar with the specific property values you mentioned, but as long as they are normally a part of Spring's ApplicationContext (where properties usually are found) then you should be able to pull in changed values using this approach with Spring's cloud config server and actuator libraries.

Hope this helps