Ribbon load balancing service call

summary

Spring Cloud Ribbon Is based on Netflix Ribbon A set of implementations client Load balancing Tools for .

To put it simply ,Ribbon yes Netflix Published open source projects , The main function is to provide Software load balancing algorithm and service invocation of client .Ribbon The client component provides a complete set of configuration items such as connection timeouts , Retry etc. . To put it simply , This is listed in the configuration file Load Balancer ( abbreviation LB) All the machines in the back ,Ribbon Will automatically help you based on certain rules ( Such as simple polling , Random connection, etc ) To connect the machines . It's easy for us to use Ribbon Implement custom load balancing algorithm .

Ribbon Official website information

Ribbon At present, it also enters maintenance mode , But still in use .

What can I do?

LB（ Load balancing ）
LB Load balancing (Load Balance) What is it? ？

To put it simply, users' requests are evenly distributed to multiple services , So as to achieve systematic HA ( High availability ). Common load balancing software Nginx, LVS, Hardware F5 etc. .

Ribbon Local load balancing client VS Nginx The difference between server-side load balancing

Nginx It's server load balancing , All client requests are delivered to nginx, Then from nginx Implement forwarding request . That is to say, the load balance is realized by the server .

Ribbon Local load balancing , When calling the microservice interface , The registration information service list will be retrieved from the registry and then cached to JVM Local , So that it can be implemented locally RPC Remote service call technology .

1.1 Centralized LB

I.e. use independent... Between consumers and providers of services LB facilities ( It can be hardware , Such as F5, It can also be software , Such as nginx), The facility is responsible for forwarding access requests through some policy to the service provider :

1.2 In process LB

take LB Logic is integrated into the consumer , The consumer knows from the service registry what addresses are available , Then I choose a suitable server from these addresses .Ribbon It's in the process LB, It's just a class library , Integrated into consumer processes , The consumer uses it to get the address of the service provider .

In a word ：

Load balancing +RestTemplate call

summary ：Ribbon In fact, it is a soft load balancing client component , It can be used in combination with other clients that require requests , and eureka Combination is just one example .

Two 、Ribbon Load balancing Demo

1. Architecture description

Ribbon Work in two steps

The first step is to choose EurekaServer , It preferentially selects the one with less load in the same area server.

The second step is according to the policy specified by the user , In from server Select an address from the service registration list .

among Ribbon There are many strategies : Like polling 、 Random and weighted by response time .

3.Ribbon Core components IRule

IRule: Select a service to be accessed from the service list according to a specific algorithm
Ribbon Seven ways of load balancing ：

The default is polling algorithm , How to replace ？

1. Create a configuration class .

@Configuration
public class MySelfRule {

    @Bean
    public IRule myRule(){
        return new RandomRule();// Defined as random 
    }
}

Be careful ： This configuration class cannot be in @CompontentScan Under the current package and sub package scanned , Otherwise, the configuration class we defined will be used by all Ribbon Shared by the client , Can not achieve the purpose of special customization .

2. Modify the startup class

@SpringBootApplication
@EnableEurekaClient
@RibbonClient(name = "CLOUD-PAYMENT-SERVICE",configuration = MySelfRule.class)
public class OrderMain80 {
    public static void main(String[] args) {
        SpringApplication.run(OrderMain80.class,args);
    }
}

add @RibbonClient(name = "CLOUD-PAYMENT-SERVICE",configuration = MySelfRule.class) Annotations can be ！！

4. Principle of load balancing algorithm