This is about zuul and routing

Question

This question is about zuul and routing. Now to get zuul routing is quite easy in your application.yml you have the following

routes:
    silver:
      path: "/silver/**"
      serviceId: "SILVER-MICO-SERVICE"
      stripPrefix: true
    gold:
      path: "/gold/**"
      serviceId: "GOLD-MICO-SERVICE"
      stripPrefix: false

So if your URL has silver in it, it will direct the silver micro service, if it has gold it directs to the gold micro service.

But I have a 3rd service, that I want to call before I direct the to the silver or gold. so i want something like

routes:
    silver:
      path: "/silver/**"
      serviceId: "SILVER-MICO-SERVICE"
      stripPrefix: true
    gold:
      path: "/gold/**"
      serviceId: "GOLD-MICO-SERVICE"
      stripPrefix: false
   throttle
     path: "/throttle/**"
      serviceId: "THROTTLE-MICO-SERVICE"
      stripPrefix: false

And when say silver is called

I will have the following in my filter, I would have a throttleFilter which will call out to the throttle micro service. But I have no idea how to code a zuul call in Java.

Thanks for any help

Answer 1

You do not need to route to throttle micro service cause you can route to only one micro service. Instead you can write a pre filter and call throttle micro service. Here is an example of how to write a pre filter

import com.netflix.zuul.ZuulFilter;
import com.netflix.zuul.context.RequestContext;

import javax.servlet.http.HttpServletRequest;

public class SimplePreFilter extends ZuulFilter {

    @Override
    public String filterType() {
        return "pre";
    }

    @Override
    public int filterOrder() {
        return 1;
    }

    @Override
    public boolean shouldFilter() {
        //You can apply custom logic if required
        return true;
    }

    @Override
    public Object run() {
        RequestContext ctx = RequestContext.getCurrentContext();
        HttpServletRequest request = ctx.getRequest();
        //TODO you can call throttle micro service here
        return null;
    }

}

Answer 2

Ok this is the code to do what I want to do. The functionality I needed was supplied by the EurekaClient

zuul 
    throttling:
      path: "/throttling/**"
      serviceId: "SITE-THROTTLING"
      stripPrefix: false

And in the code I have

@Autowired
private EurekaClient eurekaClient;

private boolean checkThrottling(String url) {
        
        InstanceInfo service = eurekaClient
                  .getApplication("SITE-THROTTLING")
                  .getInstances()
                  .get(0);
        StringBuilder sb = new StringBuilder(service.getHomePageUrl())
                .append("/throttling")
                .append("?paramUrl=")
                .append(url);
        return webSevice.sendPost(sb.toString());

public boolean sendPost(String url) {
        WebClient webClient = WebClient.create();
        Boolean flag = webClient.get()
                                       .uri(url)
                                       .retrieve()
                                       .bodyToMono(Boolean.class)
                                       .block();
        return flag;