Nacos实现Spring Cloud Gateway的动态路由

前言

方案参考：https://www.cnblogs.com/zlt2000/p/11712943.html

网关的核心概念就是路由配置和路由规则，而作为所有请求流量的入口，在实际生产环境中为了保证高可靠和高可用，是尽量要避免重启的，所以实现动态路由是非常有必要的；本文主要介绍Spring Cloud Gateway实现的思路，并且以Nacos为数据源来讲解

实现要点

要实现动态路由只需关注下面4个点

1. 网关启动时，动态路由的数据怎样加载进来
2. 静态路由与动态路由以哪个为准，ps：静态路由指的是配置文件里写死的路由配置
3. 监听动态路由的数据源变化
4. 数据有变化时怎样通知gateway刷新路由

具体实现

Spring Cloud Gateway中加载路由信息分别由以下几个类负责

• PropertiesRouteDefinitionLocator：从配置文件中读取路由信息(如YML、Properties等)
• RouteDefinitionRepository：从存储器中读取路由信息(如内存、配置中心、Redis、MySQL等)
• DiscoveryClientRouteDefinitionLocator：从注册中心中读取路由信息(如Nacos、Eurka、Zookeeper等)

我们可以通过自定义RouteDefinitionRepository的实现类来实现动态路由的目的

添加依赖

<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>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-webflux</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-configuration-processor</artifactId>
    <optional>true</optional>
</dependency>

静态路由示例

spring:
  cloud:
    gateway:
      discovery:
        locator:
          lowerCaseServiceId: true
          enabled: true
      routes:
        - id: auth
          uri: lb://uaa-server
          predicates:
            - Path=/api-uaa/**
          filters:
            - StripPrefix=1
            - PreserveHostHeader

实现动态路由的数据加载

创建一个Nacos的RouteDefinitionRepository实现类

• 重写getRouteDefinitions方法实现路由信息的读取
• 配置Nacos监听器，监听路由配置信息的变化
• 路由变化只需要往ApplicationEventPublisher推送一个RefreshRoutesEvent事件即刻，Gateway会自动监听该事件并调用getRouteDefinitions方法更新路由信息

import cn.hutool.core.collection.CollUtil;
import cn.hutool.core.util.StrUtil;
import com.alibaba.cloud.nacos.NacosConfigProperties;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.nacos.api.config.listener.Listener;
import com.alibaba.nacos.api.exception.NacosException;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.gateway.event.RefreshRoutesEvent;
import org.springframework.cloud.gateway.route.RouteDefinition;
import org.springframework.cloud.gateway.route.RouteDefinitionRepository;
import org.springframework.context.ApplicationEventPublisher;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Executor;

/**
 * nacos路由数据源
 */
@Slf4j
public class NacosRouteDefinitionRepository implements RouteDefinitionRepository {
    private static final String SCG_DATA_ID = "scg-routes";
    private static final String SCG_GROUP_ID = "SCG_GATEWAY";

    private ApplicationEventPublisher publisher;

    private NacosConfigProperties nacosConfigProperties;

    public NacosRouteDefinitionRepository(ApplicationEventPublisher publisher, NacosConfigProperties nacosConfigProperties) {
        this.publisher = publisher;
        this.nacosConfigProperties = nacosConfigProperties;
        addListener();
    }

    @Override
    public Flux<RouteDefinition> getRouteDefinitions() {
        try {
            String content = nacosConfigProperties.configServiceInstance().getConfig(SCG_DATA_ID, SCG_GROUP_ID,5000);
            List<RouteDefinition> routeDefinitions = getListByStr(content);
            return Flux.fromIterable(routeDefinitions);
        } catch (NacosException e) {
            log.error("getRouteDefinitions by nacos error", e);
        }
        return Flux.fromIterable(CollUtil.newArrayList());
    }

    /**
     * 添加Nacos监听
     */
    private void addListener() {
        try {
            nacosConfigProperties.configServiceInstance().addListener(SCG_DATA_ID, SCG_GROUP_ID, new Listener() {
                @Override
                public Executor getExecutor() {
                    return null;
                }

                @Override
                public void receiveConfigInfo(String configInfo) {
                    publisher.publishEvent(new RefreshRoutesEvent(this));
                }
            });
        } catch (NacosException e) {
            log.error("nacos-addListener-error", e);
        }
    }

    @Override
    public Mono<Void> save(Mono<RouteDefinition> route) {
        return null;
    }

    @Override
    public Mono<Void> delete(Mono<String> routeId) {
        return null;
    }

    private List<RouteDefinition> getListByStr(String content) {
        if (StrUtil.isNotEmpty(content)) {
            return JSONObject.parseArray(content, RouteDefinition.class);
        }
        return new ArrayList<>(0);
    }
}

创建配置类

创建配置类DynamicRouteConfig

import com.alibaba.cloud.nacos.NacosConfigProperties;
import com.central.gateway.route.NacosRouteDefinitionRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * 动态路由配置
 */
@Configuration
@ConditionalOnProperty(prefix = "appblog.gateway.dynamicRoute", name = "enabled", havingValue = "true")
public class DynamicRouteConfig {
    @Autowired
    private ApplicationEventPublisher publisher;

    /**
     * Nacos实现方式
     */
    @Configuration
    @ConditionalOnProperty(prefix = "appblog.gateway.dynamicRoute", name = "dataType", havingValue = "nacos", matchIfMissing = true)
    public class NacosDynRoute {
        @Autowired
        private NacosConfigProperties nacosConfigProperties;

        @Bean
        public NacosRouteDefinitionRepository nacosRouteDefinitionRepository() {
            return new NacosRouteDefinitionRepository(publisher, nacosConfigProperties);
        }
    }
}

添加Nacos路由配置

新增配置项：

• Data Id：scg-routes
• Group：SCG_GATEWAY

添加两条路由数据，配置内容：

[
    {
        "id": "appblog",
        "predicates": [{
            "name": "Path",
            "args": {
                "pattern": "/appblog/**"
            }
        }],
        "uri": "http://www.appblog.cn/",
        "filters": []
    },
    {
        "id": "github",
        "predicates": [{
            "name": "Path",
            "args": {
                "pattern": "/github/**"
            }
        }],
        "uri": "https://github.com/",
        "filters": []
    }
]

测试

启动网关通过/actuator/gateway/routes端点查看当前路由信息

可以看到Nacos里配置的两条路由信息