While I am trying to reach the service meeting
via Zuul gateway, Zuul is unable to forward the request to the respective service. The following errors are what I am facing:
- nettflix.zuul.exception.ZuulException: Forwarding error
- Caused by: com.netflix.client.ClientException: Load balancer does not have available server for client: meeting
Let me share the application.yml for the service, eureka and zuul gateway.
EurekaClient:
Application.yml
server:
port: 8761
eureka:
instance:
hostname: localhost
lease-renewal-interval-in-seconds: 300
client:
register-with-eureka: false
fetch-registry: true
serviceUrl:
defaultZone: http://localhost:8761/eureka/
ZuulGateWay:
application.yml
server:
port: 8085
spring:
application:
name: gatekeeper
zuul:
routes:
meeting: /meeting/**
serviceId: meeting
ribbon:
eureka:
enabled: false
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/
ZuulGateWay: SpringBootApplication
package com.sagarp.gatekeeper;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.zuul.EnableZuulProxy;
@SpringBootApplication
@EnableEurekaClient
@EnableZuulProxy
public class MeetingApplication {
public static void main(String[] args) {
SpringApplication.run(MeetingApplication.class, args);
}
}
My Service class (meeting): Application.yml
server:
port: 0
spring:
application:
name: meeting
datasource:
url: jdbc:mysql://localhost:3306/sagarp?useSSL=false
username: myUserName
password: myPassWord
jpa:
properties:
hibernate:
dialect: org.hibernate.dialect.MySQL5InnoDBDialect
hibernate:
ddl-auto: update
eureka:
client:
registerWithEureka: true
fetchRegistry: true
serviceUrl:
defaultZone: http://localhost:8761/eureka/
instance:
lease-renewal-interval-in-seconds: 5
My Service class (meeting): SpringBootApplication
package com.sagarp;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
@SpringBootApplication
@EnableEurekaClient
public class MeetingApplication {
public static void main(String[] args) {
SpringApplication.run(MeetingApplication.class, args);
}
}
As you can see, the configuration ensures that all my services are discovered by eureka client.
In the eureka console, I have verified the same, the zuul gateway
and my service(meeting)
both are visible.
For better view, you can visit my git repo. https://github.com/sagar-patro/demo-microservices
Any help would be very much appreciable
ribbon:
eureka:
enabled: false
Spring Cloud Netflix Zuul uses Netflix’s Ribbon to perform client-side load balancing, and by default, Ribbon would use Netflix Eureka for service discovery. You are skipping service discovery, so you've set ribbon.eureka.enabled
to false
. Since Ribbon now can’t use Eureka to look up services, you must specify an url for the meeting
service:
meeting:
ribbon:
listOfServers: localhost:8080
I will make it more clear for you.
The dependency org.springframework.cloud:spring-cloud-starter-netflix-zuul
, which you are currently using in the gatekeeper
project, has several compile dependencies:
com.netflix.zuul:zuul-core
org.springframework.boot:spring-boot-starter-web
org.springframework.boot:spring-boot-starter-actuator
org.springframework.cloud:spring-cloud-netflix-zuul
org.springframework.cloud:spring-cloud-starter
org.springframework.cloud:pring-cloud-starter-netflix-hystrix
org.springframework.cloud:spring-cloud-starter-netflix-ribbon
org.springframework.cloud:spring-cloud-starter-netflix-archaius
As you see, it constitutes many components gathered around the com.netflix.zuul:zuul-core
module (including Eureka for instance discovery and Ribbon for routing):
When you are launching the gatekeeper
application, the default ZuulProxyAutoConfiguration
configuration is being applied. It imports Ribbon configuration classes:
@Configuration
@Import({ RibbonCommandFactoryConfiguration.RestClientRibbonConfiguration.class,
RibbonCommandFactoryConfiguration.OkHttpRibbonConfiguration.class,
RibbonCommandFactoryConfiguration.HttpClientRibbonConfiguration.class,
HttpClientConfiguration.class })
@ConditionalOnBean(ZuulProxyMarkerConfiguration.Marker.class)
public class ZuulProxyAutoConfiguration extends ZuulServerAutoConfiguration { ... }
HttpClientRibbonConfiguration
, in turn, initialises RibbonLoadBalancingHttpClient
which is responsible for the error messages you saw.
That RibbonLoadBalancingHttpClient
by default utilises ZoneAwareLoadBalancer
which comes from a com.netflix.ribbon:ribbon-loadbalancer
package:
By default Zuul load balances using the
ZoneAwareLoadBalancer
from Ribbon. The algorithm is a round robin of the instances available in discovery, with availability zone success tracking for resiliency. The load balancer will keep stats for each zone and will drop a zone if the failure rates are above a configurable threshold.If you want to use your own custom load balancer you can set the
NFLoadBalancerClassName
property for that Ribbon client namespace or override thegetLoadBalancerClass()
method in theDefaultClientChannelManager
. Note that your class should extendDynamicServerListLoadBalancer
.
It explains that Zuul delegates routing and load balancing work to Ribbon components and proves that you are actually using Ribbon in the gatekeeper
project.
Unless you choose a different load balancer, you should go for my original answer.
I hope it will help.