spring-gateway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);
 }
 
}