I managed to have ribbon dynamically discover instances in a k8s cluster using kubeflix and spring-cloud-kubernetes
This was when I manually used Ribbon to communicate between my microservices.
Zuul automatically uses Ribbon for the routes defined in its configuration.
Has anyone managed to enable Ribbon discovery for Zuul? I think I would need to override the instance of LoadBalancer for each of the routes. Any ideas how to do that?
That was actually quite easy. You only need to specify the NIWSServerListClassName, the k8s namespace and the k8s port name in the Ribbon configuration:
service-name:
ribbon:
NIWSServerListClassName: io.fabric8.kubeflix.ribbon.KubernetesServerList
KubernetesNamespace: uat
PortName: tcp80 #make sure you this matches the port name in the k8s service (kubectl describe svc service-name)
Then the Zuul route can refer to the service:
zuul:
routes:
rm-data-store:
path: /foo/**
retryable: true
service-id: service-name
Related
I don't have eureka, load balancer and so on. I want to load balance the request to list of URIs on which instances of backend run.
spring:
cloud:
gateway:
routes:
- id: myService-endpoints
uri: myServiceIp1, myServiceIp2
predicates:
- Path=/myservice/**
myServiceIp1 and myServiceIp2 are my backend service IPs. How can I achieve load balancing in this scenario?
If you are not using service registry, you can still use load-balancing in your app. You will just need to use the SimpleDiscoveryClient that allows you to set your service instance URIs via a property file, like so:
spring.cloud.discovery.client.simple.instances.service1[0].uri=http://s11:8080
Then you can just follow the guides for setting up load-balanced routes in Gateway, like so:
spring:
cloud:
gateway:
routes:
- id: myRoute
uri: lb://service
predicates:
- Path=/service/**
In Spring Boot Microservices architecture, we generally register our each microservice (its many instances) into Eureka server by doing eureka.client.register-with-eureka=true, eureka.client.fetch-registry=true and eureka.client.serviceUrl.defaultZone=http://localhost:8761/eureka. So Eureka acts as service registry for these services (service-name, hostname and its IP).
Spring Cloud API Gateway acts as a single point of entry for any microservice call. It can work as a proxy service to route a request to the concerned microservice, abstracting the producer details. It has route information only, then how Spring Cloud API gateway comes to know which microservice instance to call to? How API Gateway and Eureka communicates and load balance?
spring:
application:
name: api-gateway
cloud:
gateway:
discovery:
locator:
enabled: true
lower-case-service-id: true
routes:
- id: user-service
uri: lb://user-service
predicates:
- Path=/users/**
- id: order-service
uri: lb://department-service
predicates:
- Path=/departments/**
spring:
cloud:
gateway:
discovery:
locator:
enabled: true
With the Discovery Locator enabled in API Gateway, you do not have to manually configure the routes unless absolutely needed.
The way API Gateway knows which Eureka Service to route the incoming request to is as follows:
Assuming,
Orders Service runs on http://localhost:8080
API Gateway runs on http://localhost:8082
Eureka Service name for Orders Service - order-service
Then if order-service getOrders endpoint: http://localhost:8080/orders, then with Discovery Locator enabled the request needs to be routed through the API gateway with the following URL: https://localhost:8082/order-service/orders, i.e., {ApiGatewayHost}/{EurekaServiceId}/{ActualEndpoint}.
Register Gatway to Eureka Server
Through reading various books / tutorials, it appears that it is possible to auto-configure routes in Zuul when using it in combination with Eureka service discovery. That means that I don't have to explicitly add routes to Zuul's application.properties.
So I understand this correctly? Or do I still need to add routes explicitly to Zuul in order it to work as a gateway?
I would like it to automatically create routes from the application name's that are registered with Eureka. Is this possible?
(Note: I have actually tried this, but when I go to http://localhost:8762/routes I just get an error page.)
Sure. In most microservices implementations, internal microservices endpoints are not exposed outside. A set of public services will be exposed to the clients using an API gateway.
The zuul proxy internally uses the Eureka Server for service discovery.
I would like it to automatically create routes from the application name's that are registered with Eureka. Is this possible?
Sure. I will show you gateway example.
1. Create your service project (user-service)
create application.properties file
# --- Spring Config
spring:
application:
name: OVND-USER-SERVICE
# Eureka client
eureka:
client:
serviceUrl:
defaultZone: ${EUREKA_URL:http://localhost:8761/eureka/}
2. Setting up Zuul project (Gateway-service)
1.#EnableZuulproxy to tell Spring Boot that this is a Zuul proxy
#SpringBootApplication
#EnableZuulProxy
#EnableDiscoveryClient
public class GatewayServiceApplication {
2.create an application.properties file
# =======================================
# Gateway-service Server Configuration
# =======================================
# --- Spring Config
spring:
application:
name: gateway-service
server:
port: ${PORT:8080}
# Eureka client
eureka:
client:
serviceUrl:
defaultZone: ${EUREKA_URL:http://localhost:8761/eureka/}
zuul:
host:
routes:
## By default, all requests to user service for example will start with: "/user/"
## What will be sent to the user service is what comes after the path defined,
## So, if request is "/user/v1/user/tedkim", user service will get "/v1/user/tedkim".
user-service:
path: /user/**
service-id: OVND-USER-SERVICE
another-service:
path: /another/**
service-id: OVND-ANOTHER-SERVICE
Eureka website ( localhost:8761 )
Yes. You can integrate Zuul with Eureka and configure the routes based on application names registered in Eureka. Just add the following configuration to Zuul application:
zuul:
ignoredServices: "*"
routes:
a-service: /a-service/**
b-service: /b-service/**
c-service: /c-service/**
d-service: /d-service/**
Do we need to configure both Ribbon and Zuul for Loadbalancing the microservices.
From what I have seen Zuul is more of a conventional reverse-proxy loadbalancer and any request to services thro Zuul will automatically be loadbalanced and I do not have to configure Ribbon in individual microservices.
We will need Ribbon configured in the service only if we need to connect to a service that is not proxied by Zuul.
Is the understanding correct.
If you are using eureka for discovering your services, that are balanced through zuul, you don't need to configure ribbon in any way.
Say, you have a ServiceA that is discovered by eureka and you have a zuul route configured like this one
zuul:
routes:
example:
path: /example/**
serviceId: ServiceA
As soon as you have more than one instance of ServiceA running, zuul will start to load balance the load of all ServiceA with a round robin algorithm.
I have some web services registered at Spring Boot Eureka Server. Is there any way I can check the endpoints registered at Eureka Server, with respect to all the application?
e.g: Eureka server
Service1 means Request will be routed to service endpoint: localhost:9080/service1
Service2 means Request will be routed to service endpoint: localhost:9088/service2
Service3 means Request will be routed to service endpoint: localhost:9085/service3
You can check the Eureka dashboard at http://host-name:8761 (Change the port if you're using a different one).
Secondly, Eureka doesn't route any request. It is just a service registry and keeps the records of the Microservices and its instances. You need an API Gateway (ZUUL) or similar to do the routing along with client side load balancers (ribbon, etc.).
You can configure the zuul endpoints in the application.yml (or properties) file like below to access your service endpoints.
zuul:
ignoredServices: "*"
routes:
service1:
path: /service1/**
service2:
path: /service2/**
If you want to access the service1, then your endpoint will be something like http://localhost:8765/service1/{custom-path}
Note: 8765 is the default zuul port. Change it accordingly.