Zuul and Eureka setup acting strange - spring

Question

I have setup a zuul proxy with eureka(not as a separate service).
Sometimes when i try to proxy to my service I get the following error:
12-04-2019 13:03:05.667 [http-nio-8761-exec-8] WARN o.s.c.n.z.f.post.SendErrorFilter.run - Error during filtering
com.netflix.zuul.exception.ZuulException: Forwarding error
at org.springframework.cloud.netflix.zuul.filters.route.RibbonRoutingFilter.handleException(RibbonRoutingFilter.java:198)
at org.springframework.cloud.netflix.zuul.filters.route.RibbonRoutingFilter.forward(RibbonRoutingFilter.java:173)
at org.springframework.cloud.netflix.zuul.filters.route.RibbonRoutingFilter.run(RibbonRoutingFilter.java:119)
at com.netflix.zuul.ZuulFilter.runFilter(ZuulFilter.java:117)
at com.netflix.zuul.FilterProcessor.processZuulFilter(FilterProcessor.java:193)
at com.netflix.zuul.FilterProcessor.runFilters(FilterProcessor.java:157)
at com.netflix.zuul.FilterProcessor.route(FilterProcessor.java:118)
at com.netflix.zuul.ZuulRunner.route(ZuulRunner.java:96)
at com.netflix.zuul.http.ZuulServlet.route(ZuulServlet.java:116)
at com.netflix.zuul.http.ZuulServlet.service(ZuulServlet.java:81)
at org.springframework.web.servlet.mvc.ServletWrappingController.handleRequestInternal(ServletWrappingController.java:165)
at org.springframework.cloud.netflix.zuul.web.ZuulController.handleRequest(ZuulController.java:45)
at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:52)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038)
...........................
After that it says:
Caused by: com.netflix.client.ClientException: Load balancer does not have available server for client: EXAMPLE-SERVICE
at com.netflix.loadbalancer.LoadBalancerContext.getServerFromLoadBalancer(LoadBalancerContext.java:483)
at com.netflix.loadbalancer.reactive.LoadBalancerCommand$1.call(LoadBalancerCommand.java:184)
at com.netflix.loadbalancer.reactive.LoadBalancerCommand$1.call(LoadBalancerCommand.java:180)
at rx.Observable.unsafeSubscribe(Observable.java:10327)
at rx.internal.operators.OnSubscribeConcatMap.call(OnSubscribeConcatMap.java:94)
at rx.internal.operators.OnSubscribeConcatMap.call(OnSubscribeConcatMap.java:42)
at rx.Observable.unsafeSubscribe(Observable.java:10327)
at rx.internal.operators.OperatorRetryWithPredicate$SourceSubscriber$1.call(OperatorRetryWithPredicate.java:127)
at rx.internal.schedulers.TrampolineScheduler$InnerCurrentThreadScheduler.enqueue(TrampolineScheduler.java:73)
at rx.internal.schedulers.TrampolineScheduler$InnerCurrentThreadScheduler.schedule(TrampolineScheduler.java:52)
at rx.internal.operators.OperatorRetryWithPredicate$SourceSubscriber.onNext(OperatorRetryWithPredicate.java:79)
at rx.internal.operators.OperatorRetryWithPredicate$SourceSubscriber.onNext(OperatorRetryWithPredicate.java:45)
at rx.internal.util.ScalarSynchronousObservable$WeakSingleProducer.request(ScalarSynchronousObservable.java:276)
at rx.Subscriber.setProducer(Subscriber.java:209)
at rx.internal.util.ScalarSynchronousObservable$JustOnSubscribe.call(ScalarSynchronousObservable.java:138)
at rx.internal.util.ScalarSynchronousObservable$JustOnSubscribe.call(ScalarSynchronousObservable.java:129)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
.........................
I try a couple more requests on the same endpoint and it prints this:
12-04-2019 13:03:20.417 [PollingServerListUpdater-0] INFO c.n.config.ChainedDynamicProperty.checkAndFlip - Flipping property: EXAMPLE-SERVICE.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647
And suddenly everything works....??!??
Here is some info about both services:
Eureka/Proxy Service:
//application.properties
server.port=8761
spring.application.name=proxyservice
#This is a eureka server so no need to register
eureka.client.register-with-eureka=false
#This is a eureka server no need to fetch registry
eureka.client.fetch-registry=true
#Register url for client
eureka.client.service-url.defaultZone=http://localhost:8761/eureka
#Zuul proxying
#All url come with prefix/api will interpret
zuul.prefix=/api
ribbon.ReadTimeout=60000
#Routes
zuul.routes.student-service.path=/example/**
zuul.routes.student-service.serviceId=EXAMPLE-SERVICE
//pom.xml
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Greenwich.SR1</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-zuul</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-security</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.security</groupId>
<artifactId>spring-security-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
//Application.java
#EnableZuulProxy
#EnableEurekaServer
#SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
EXAMPLE-SERVICE:
//application.properties
server.port=8098
eureka.client.serviceUrl.defaultZone=http://localhost:8761/eureka/
eureka.client.healthcheck.enabled=true
spring.application.name=sirma-service

Answer 1

Need to use Eureka Discovery Client because you have mentioned eureka.client.service-url.defaultZone for Eureka Client and you are using in Application #EnableEurekaServer.
You need to use #EnableDiscoveryClient, So that Your Application will be registered with Eureka Naming Server.