Spring Gateway集成 Nacos注册中心不能够发现服务的解决方案_Java

一、问题描述

我们现在是在用nacos替换eureka，原来eureka和spring gateway运行正常，可以通过spring gateway调用注册到eureka中的服务。

当前spring cloud的版本是hoxton.sr8，nacos discovery的版本为0.9.0.release，使用的nacos版本为2.0.3。

nacos替换eureka改动的地方如下：

１、去掉pom中eureka的引入；

２、去掉主类中引入的@enableeurekaclient注解；

３、引入nacos依赖：

<dependency>
  <groupid>org.springframework.cloud</groupid>
  <artifactid>spring-cloud-starter-alibaba-nacos-discovery</artifactid>
  <version>0.9.0.release</version>
  <exclusions>
    <exclusion>
        <groupid>com.alibaba.nacos</groupid>
        <artifactid>nacos-client</artifactid>
    </exclusion>
    <exclusion>
     <groupid>org.springframework.cloud</groupid>
     <artifactid>spring-cloud-starter-netflix-ribbon</artifactid>
    </exclusion>
  </exclusions>
</dependency>
<dependency>
  <groupid>com.alibaba.nacos</groupid>
  <artifactid>nacos-client</artifactid>
  <version>2.0.3</version>
</dependency>

４、引入spring-cloud-loadbalancer：

<dependency>
	<groupid>org.springframework.cloud</groupid>
	<artifactid>spring-cloud-loadbalancer</artifactid>
</dependency>

５、spring-cloud-starter-openfeign中exclude掉ribbon的依赖：

<dependency>
    <groupid>org.springframework.cloud</groupid>
    <artifactid>spring-cloud-starter-openfeign</artifactid>
    <exclusions>
        <exclusion>
            <groupid>org.springframework.cloud</groupid>
            <artifactid>spring-cloud-netflix-ribbon</artifactid>
        </exclusion>
    </exclusions>
</dependency>

６、application.yml中禁用nacos的ribbon：

ribbon:
  nacos:
    enabled: false

现在的现象：

spring gateway启动不报错；
gateway也可以正常注册到nacos；
通过打断点到nacosdiscoveryclientautoconfiguration，nacosdiscoveryclient会被初使化，但是调用时不会调用nacosdiscoveryclient.getinstances(string)获取被调用应用的provider，会报类似下面的接口404错误：

{"msg":"/user-service/user/getbytoken","result":404,"data":null}

其中user-service为注册到nacos上面的服务名称，但是就是不能够被调用到。

spring gateway的注册中心切换为eureka，再次调用服务时，eureka的compositediscoveryclient.getinstances(string)方法就会被调用。

二、问题分析

前面走了一些弯路，也花了一些时间，最后想到的是与eureka注册中心进行对比调试分析，下面例出关键的分析步骤。

debug断点打到discoveryclientroutedefinitionlocator两个构造函数上，只有参数是reactivediscoveryclient的构造函数被加载：

继续跟踪到reactivecompositediscoveryclient.getservices()方法：

发现数组变量discoveryclients包含了两个实现，如下图所示：

其中有一个是eurekareactivediscoveryclient，那在使用nacos时就应该包含一个针对nacos实现的reactivediscoveryclient，于是切换为nacos分支调试。

但是调试发现数组变量discoveryclients并没有包含针对nacos实现的reactivediscoveryclient：

于是参考eurekareactivediscoveryclient以及nacosdiscoveryclient，立即就写了nacosreactivediscoveryclient：

import java.util.arraylist;
import java.util.collections;
import java.util.hashmap;
import java.util.list;
import java.util.map;
import org.springframework.cloud.alibaba.nacos.nacosdiscoveryproperties;
import org.springframework.cloud.alibaba.nacos.nacosserviceinstance;
import org.springframework.cloud.client.serviceinstance;
import org.springframework.cloud.client.discovery.reactivediscoveryclient;
import com.alibaba.nacos.api.naming.pojo.instance;
import com.alibaba.nacos.api.naming.pojo.listview;
import lombok.extern.slf4j.slf4j;
import reactor.core.publisher.flux;
/**
 * 
 * @author fenglibin
 *
 */
@slf4j
public class nacosreactivediscoveryclient implements reactivediscoveryclient {
	public static final string description = "spring cloud nacos reactive discovery client";
	private nacosdiscoveryproperties discoveryproperties;
	public nacosreactivediscoveryclient(nacosdiscoveryproperties discoveryproperties) {
		this.discoveryproperties = discoveryproperties;
	}
	@override
	public string description() {
		return description;
	}
	@override
	public flux<serviceinstance> getinstances(string serviceid) {
		try {
			list<instance> instances = discoveryproperties.namingserviceinstance().selectinstances(serviceid, true);
			return flux.fromstream(hosttoserviceinstancelist(instances, serviceid).stream());
		} catch (exception e) {
			throw new runtimeexception("can not get hosts from nacos server. serviceid: " + serviceid, e);
		}
	}
	@override
	public flux<string> getservices() {
		try {
			listview<string> services = discoveryproperties.namingserviceinstance().getservicesofserver(1,
					integer.max_value);
			return flux.fromstream(services.getdata().parallelstream());
		} catch (exception e) {
			log.error("get service name from nacos server fail,", e);
			return flux.fromstream(collections.<string>emptylist().stream());
		}
	}
	private static serviceinstance hosttoserviceinstance(instance instance, string serviceid) {
		nacosserviceinstance nacosserviceinstance = new nacosserviceinstance();
		nacosserviceinstance.sethost(instance.getip());
		nacosserviceinstance.setport(instance.getport());
		nacosserviceinstance.setserviceid(serviceid);
		map<string, string> metadata = new hashmap<>();
		metadata.put("nacos.instanceid", instance.getinstanceid());
		metadata.put("nacos.weight", instance.getweight() + "");
		metadata.put("nacos.healthy", instance.ishealthy() + "");
		metadata.put("nacos.cluster", instance.getclustername() + "");
		metadata.putall(instance.getmetadata());
		nacosserviceinstance.setmetadata(metadata);
		if (metadata.containskey("secure")) {
			boolean secure = boolean.parseboolean(metadata.get("secure"));
			nacosserviceinstance.setsecure(secure);
		}
		return nacosserviceinstance;
	}
	private static list<serviceinstance> hosttoserviceinstancelist(list<instance> instances, string serviceid) {
		list<serviceinstance> result = new arraylist<>(instances.size());
		for (instance instance : instances) {
			result.add(hosttoserviceinstance(instance, serviceid));
		}
		return result;
	}
}

或者集成如下starter：

    <dependency>
        <groupid>com.eeeffff</groupid>
        <artifactid>nacos-reactive-discovery-client</artifactid>
        <version>1.0.0</version>
    </dependency>

并在启动时创建bean：