Spring Cloud Netflix Ribbon核心接口

Spring Cloud Netflix Ribbon核心接口

LoadBalancerClient

主要職責

• 轉化URI：將含應用名稱URI轉化成具體主機+端口形式
• 選擇服務實例:通過負載算法，選擇指定服務中的一臺機器實例
• 請求執行回調：針對選擇後服務實例，執行具體的請求回調操作
  默認實現：RibbonLoadBalancerClient

自動裝配源：RibbonAutoConfiguration#loadBalancerClient（...）

負載均衡器上下文

LoadBalancerContext

主要職責

• 轉化URI：將含應用名稱URI轉化成具體主機+端口的形式
• 組件關聯：關聯RetryHandler、ILoadBalancer等
• 記錄服務統計信息：記錄請求響應時間、錯誤數量等
• 默認實現：RibbonLoadBalancerContext
• 自動裝配源：RibbonClientConfiguration#ribbonLoadBalancerContext（...）

負載均衡器

ILoadBalancer

主要職責

• 增加服務器
• 獲取服務器：通過關聯Key獲取、獲取所有服務列表、獲取可用服務器列表
• 服務器狀態：標記服務器宕機
• 默認實現：ZoneAwareLoadBalancer
• 自動裝配源：RibbonClientConfiguration#ribbonLoadBalancer（...）

規則接口

IRule

主要職責

• 選擇服務器：根據負載均衡器以及關聯Key獲取候選的服務器
• 默認實現：ZoneAvoidanceRule
• 自動裝配源：RibbonClientConfiguration#ribbonRule（...）

PING策略

IPing

主要職責

• 活動檢測：根據指定的服務器，檢測其是否活動
• 默認實現：DummyPing
• 自動裝配源：RibbonClientConfiguration#ribbonPing（...）

服務器列表

ServerList

主要職責

• 獲取初始化服務器列表
• 獲取更新服務器列表
• 默認實現：ConfigurationBasedServerList或DiscoveryEnabledNIWSServerList
• 自動裝配源：RibbonClientConfiguration#ribbonPing（...）

我的項目版本信息Maven配置

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <modules>
      <module>user-api</module>
   </modules>
   <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>2.1.3.RELEASE</version>
      <relativePath/> <!-- lookup parent from repository -->
   </parent>
   <groupId>com.example</groupId>
   <artifactId>spring-cloud-lesson-7</artifactId>
   <version>0.0.1-SNAPSHOT</version>
   <packaging>pom</packaging>
   <name>spring-cloud-lesson-7</name>
   <description>Demo project for Spring Boot</description>

   <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-actuator</artifactId>
      </dependency>
      <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-client</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-ribbon</artifactId>
      </dependency>

      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-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>

   <build>
      <plugins>
         <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
         </plugin>
      </plugins>
   </build>

</project>

idea多工程配置

pom.xml文件中

然後刪除之前src文件夾，然後new個項目，效果如圖

三個模塊：

• user-api：公用 API
• user-robbon-client：客戶端應用
• user-service-provider：服務端應用

實現 user-robbon-client

配置信息
application.properties:

## 用戶 Ribbon 客戶端應用
spring.application.name = user-ribbon-client

## 服務端口
server.port = 8080

## 提供方服務名稱
provider.service.name = user-service-provider
## 提供方服務主機
provider.service.host = localhost
## 提供方服務端口
provider.service.port = 9090

## 關閉 Eureka Client，顯示地通過配置方式註冊 Ribbon 服務地址
eureka.client.enabled = false

## 定義 user-service-provider Ribbon 的服務器地址
## 爲 RibbonLoadBalancerClient 提供服務列表
user-service-provider.ribbon.listOfServers = \
  http://${provider.service.host}:${provider.service.port}

2.編寫客戶端調用

package com.segumentfault.spring.cloud.lesson7.user.ribbon.client.web.controller;

import com.segumentfault.spring.cloud.lesson7.domain.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import javax.ws.rs.GET;
import java.io.IOException;

/**
 * 用戶 Ribbon Controller
 *
 */
@RestController
public class UserRibbonController {

    /**
     * 負載均衡器客戶端
     */
    @Autowired
    private LoadBalancerClient loadBalancerClient;

    @Value("${provider.service.name}")
    private String providerServiceName;


    @GetMapping("")
    public String index() throws IOException {

        User user = new User();
        user.setId(1L);
        user.setName("小馬哥");

        // 選擇指定的 service Id
        ServiceInstance serviceInstance = loadBalancerClient.choose(providerServiceName);

        return loadBalancerClient.execute(providerServiceName, serviceInstance, instance -> {

            //服務器實例，獲取 主機名（IP） 和 端口
            String host = instance.getHost();
            int port = instance.getPort();
            String url = "http://" + host + ":" + port + "/user/save";
            RestTemplate restTemplate = new RestTemplate();

            return restTemplate.postForObject(url, user, String.class);

        });

    }

}

3.編寫引導類

package com.segumentfault.spring.cloud.lesson7.user.ribbon.client;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.ribbon.RibbonClient;

/**
 * 引導類
 *
 */
@SpringBootApplication
@RibbonClient("user-service-provider") // 指定目標應用名稱
public class UserRibbonClientApplication {

    public static void main(String[] args) {
        SpringApplication.run(UserRibbonClientApplication.class, args);
    }
}

實現user-service-provider

1.配置信息
application.properties

## 用戶服務提供方應用信息
spring.application.name = user-service-provider

## 服務端口
server.port = 9090

## 關閉 Eureka Client，顯示地通過配置方式註冊 Ribbon 服務地址
eureka.client.enabled = false

2.實現UserService

package com.segumentfault.spring.cloud.lesson7.user.service.provider.service;

import com.segumentfault.spring.cloud.lesson7.api.UserService;
import com.segumentfault.spring.cloud.lesson7.domain.User;
import org.springframework.stereotype.Service;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * 內存實現{@link UserService}
 *
 */
@Service
public class InMemoryUserService implements UserService {

    private Map<Long, User> repository = new ConcurrentHashMap<>();

    @Override
    public boolean saveUser(User user) {
        return repository.put(user.getId(), user) == null;
    }

    @Override
    public List<User> findAll() {
        return new ArrayList(repository.values());
    }
}

3.實現Web服務

package com.segumentfault.spring.cloud.lesson7.user.service.web.controller;

import com.segumentfault.spring.cloud.lesson7.api.UserService;
import com.segumentfault.spring.cloud.lesson7.domain.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

/**
 * 用戶服務提供方 Controller
 *
 */
@RestController
public class UserServiceProviderController {

    @Autowired
    private UserService userService;

    @PostMapping("/user/save")
    public boolean user(@RequestBody User user){
        return userService.saveUser(user);
    }

}

4.編寫引導類

package com.segumentfault.spring.cloud.lesson7.user.service;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.ribbon.RibbonClient;

/**
 * 引導類
 *
 */
@SpringBootApplication
public class UserServiceProviderApplication {

    public static void main(String[] args) {
        SpringApplication.run(UserServiceProviderApplication.class, args);
    }
}

下面知識點是拓展源碼練習，只做瞭解

分析調用鏈路
選擇服務器邏輯
LoadBalancerClient（LoadBalancerClient） -> ILoadBalancer（ZoneAwareLoadBalancer） -> IRule (ZoneAvoidanceRule)

自定義實現IRule

擴展AbstractLoadBalancerRule:MyRule

package com.segumentfault.spring.cloud.lesson7.user.ribbon.client.rule;

import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.AbstractLoadBalancerRule;
import com.netflix.loadbalancer.ILoadBalancer;
import com.netflix.loadbalancer.IRule;
import com.netflix.loadbalancer.Server;

import java.util.List;

/**
 * 自定義{@link IRule} 實現，永遠選擇最後一臺可達服務器
 *
 */
public class MyRule extends AbstractLoadBalancerRule {

    @Override
    public void initWithNiwsConfig(IClientConfig clientConfig) {

    }

    @Override
    public Server choose(Object key) {

        ILoadBalancer loadBalancer = getLoadBalancer();

        //獲取所有可達服務器列表
        List<Server> servers = loadBalancer.getReachableServers();
        if (servers.isEmpty()) {
            return null;
        }

        // 永遠選擇最後一臺可達服務器
        Server targetServer = servers.get(servers.size() - 1);
        return targetServer;
    }

}

將MyRule暴露成Bean
通過ribbonClientConfiguration學習源碼

@Bean
@ConditionalOnMissingBean
public IRule ribbonRule(IClientConfig config) {
   if (this.propertiesFactory.isSet(IRule.class, name)) {
      return this.propertiesFactory.get(IRule.class, config, name);
   }
   ZoneAvoidanceRule rule = new ZoneAvoidanceRule();
   rule.initWithNiwsConfig(config);
   return rule;
}

然後將其暴露成Bean

/**
 * 將 {@link MyRule} 暴露成 {@link Bean}
 *
 * @return {@link MyRule}
 */
@Bean
public IRule myRule() {
    return new MyRule();
}

配置化實現組件
通過學習PropertiesFactory源碼

public PropertiesFactory() {
        classToProperty.put(ILoadBalancer.class, "NFLoadBalancerClassName");
        classToProperty.put(IPing.class, "NFLoadBalancerPingClassName");
        classToProperty.put(IRule.class, "NFLoadBalancerRuleClassName");
        classToProperty.put(ServerList.class, "NIWSServerListClassName");
        classToProperty.put(ServerListFilter.class, "NIWSServerListFilterClassName");
    }

可知NFLoadBalancerClassName等是可以配置的
實現IPing：MyPing

package com.segumentfault.spring.cloud.lesson7.user.ribbon.client.ping;

import com.netflix.loadbalancer.IPing;
import com.netflix.loadbalancer.Server;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.client.RestTemplate;
import org.springframework.web.util.UriComponentsBuilder;

import java.net.URI;

/**
 * 實現 {@link IPing} 接口：檢查對象 /health 是否正常狀態碼:200
 *
 */
public class MyPing implements IPing {

    @Override
    public boolean isAlive(Server server) {

        String host = server.getHost();
        int port = server.getPort();
        // /health endpoint
        // 通過 Spring 組件來實現URL 拼裝
        UriComponentsBuilder builder = UriComponentsBuilder.newInstance();
        builder.scheme("http");
        builder.host(host);
        builder.port(port);
        builder.path("/health");
        URI uri = builder.build().toUri();

        RestTemplate restTemplate = new RestTemplate();

        ResponseEntity responseEntity = restTemplate.getForEntity(uri, String.class);
        // 當響應狀態等於 200 時，返回 true ，否則 false
        return HttpStatus.OK.equals(responseEntity.getStatusCode());
    }
    
}

增加配置
application.properties

## 擴展 IPing 實現
user-service-provider.ribbon.NFLoadBalancerPingClassName = \
  com.segumentfault.spring.cloud.lesson7.user.ribbon.client.ping.MyPing