springgateway基于数据库 + nacos 的动态路由

动态路由的实现方式多种多样，研究一下基于数据方式的动态路由。

1. 创建项目，并pom.xml文件引入如下依赖

<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 https://maven.apache.org/xsd/maven-4.0.0.xsd"> 
    <modelVersion>4.0.0</modelVersion>
   <groupId>com.olive</groupId>
    <artifactId>olive-gateway</artifactId>
 <version>0.0.1-SNAPSHOT</version> 
  <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>2.7.1</version> 
  </parent>
 <dependencyManagement>
     <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>2021.0.3</version>
            <type>pom</type>
            <scope>import</scope>
   </dependency>
      <dependency>
           <groupId>com.alibaba.cloud</groupId>
           <artifactId>spring-cloud-alibaba-dependencies</artifactId>
           <version>2021.1</version>
           <type>pom</type>
           <scope>import</scope>
      </dependency>
  </dependencies>

 </dependencyManagement> 

  <dependencies>
       <dependency> 
          <groupId>org.springframework.cloud</groupId>
          <artifactId>spring-cloud-starter-gateway</artifactId>
    </dependency>
      <dependency>
           <groupId>com.alibaba.cloud</groupId>
          <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
    </dependency> 
   </dependencies>

</project>

使用 spring-boot-starter-paren t就不需要给子集pom配置版本号了，因为它包括了

• 定义了 java 编译版本为 1.8

• 使用 utf-8 格式编码

• 继承 spring-boot-dependencies 进行统一版本依赖管理

• 执行打包 war jar 操作配置；可以省略打包 plugin 的配置

• 自动化资源过滤。如 application.properties 和 application.yml 的资源过滤、 包括 profile 多环境配置的

• 自动化插件配置

• 不需要配置 maven 打包 plugin 插件配置

2. 从数据库加载路由配置

先定义一个接口，该接口的功能主要是返回数据库配置的所有路由

import org.springframework.cloud.gateway.route.RouteDefinition;
import reactor.core.publisher.Flux;

/** 
* 返回所有路由数据 
*/
public interface GatewayRouterService {
    Flux<RouteDefinition> getGatewayRoutes();
}

实现该接口

import java.util.ArrayList;import java.util.List;
import org.springframework.cloud.gateway.route.RouteDefinition;
import org.springframework.stereotype.Service;
import com.olive.router.GatewayRouterService;
import reactor.core.publisher.Flux;

@Service
public class RouterServiceImpl implements GatewayRouterService {
    
    @Override 
    public Flux<RouteDefinition> getGatewayRoutes() {
           System.out.println("------getGatewayRoutes-------");
     List<RouteDefinition> routes = null;     
         //TODO查询数据库返回所有有效路由
     return Flux.fromIterable(routes );
   }
}

3. 动态加载路由

实现 RouteDefinitionRepository  接口，Spring自动从数据库中读取路由配置；采用 nacos 作为服务发现与配置中心，nacos 自动触发心跳检测，网关基于心跳检测会自动刷新数据库路由配置，默认 30s 进行一次路由刷新。参考实现 RouteRefreshListener。

import org.springframework.cloud.gateway.route.RouteDefinition;
import org.springframework.cloud.gateway.route.RouteDefinitionRepository;
import com.olive.router.GatewayRouterService;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
public class DatabaseRouteDefinitionRepository implements RouteDefinitionRepository {
    private final GatewayRouterService gatewayRouterService;
    public InDBRouteDefinitionRepository(GatewayRouterService gatewayRouterService) {
        this.gatewayRouterService= gatewayRouterService;
    }
    @Override
    public Flux<RouteDefinition> getRouteDefinitions() {
        return gatewayRouterService.getGatewayRoutes();
    }
    @Override    
    public Mono<Void> save(Mono<RouteDefinition> route) {
        //TODO
        return Mono.empty();
    }
    @Override
    public Mono<Void> delete(Mono<String> routeId) {
    //TODO 
       return Mono.empty();
    }

}

4. 配置加载自定义的路由

spring-gateway 默认是先从 application.yml 文件加载路由配置；这里通过 AutoConfigureBefore 注解，加载数据库的路由配置。

import org.springframework.boot.autoconfigure.AutoConfigureBefore;
import org.springframework.boot.autoconfigure.AutoConfigureOrder;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.cloud.gateway.config.GatewayAutoConfiguration;
import org.springframework.cloud.gateway.route.RouteDefinitionRepository;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.Ordered;
import com.olive.route.DatabaseRouteDefinitionRepository;
import com.olive.router.GatewayRouterService;

@AutoConfigureBefore(GatewayAutoConfiguration.class)
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 5)
@Configuration
public class GatewayConfig {    

   /**
   * 网关路由配置实现bean
   */ 
   @Bean   
   @ConditionalOnMissingBean(RouteDefinitionRepository.class)
   @ConditionalOnBean(GatewayRouterService.class)
   public DatabaseRouteDefinitionRepository databaseRouteDefinitionRepository(GatewayRouterService gatewayRouterService) {
        return new DatabaseRouteDefinitionRepository(gatewayRouterService);    
    }
}

5. 添加 application.yml 配置文件

需要启动nacos，然后要配置 nacos 注册中心地址。

server:
  port: 8089
spring:
  application:
    name: olive-gateway
  cloud:
    nacos: 
     discovery: 
       server-addr: 192.168.255.10:8848

6. 编写 springboot  启动引导类

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@EnableDiscoveryClient
@SpringBootApplication
public class GwApplication {
 public static void main(String[] args) {
   SpringApplication.run(GwApplication.class, args);
 }
}