Nacos

更好的发现、配置和管理微服务

• 动态服务发现, 服务健康监测
• 配置管理

服务注册与发现

@startuml Nacos 服务注册发现原理


actor 服务提供者 as Provider
participant "Nacos 客户端" as SDK
participant "Nacos 服务器" as Server
actor 服务消费者 as Consumer

' 样式定义
skinparam participant {
  BackgroundColor #f0f8ff
  BorderColor #2c3e50
}
skinparam actor {
  BackgroundColor #e8f4fd
  BorderColor #2980b9
}
skinparam note {
  BackgroundColor #fff3cd
  BorderColor #f39c12
}

== 1. 服务注册流程 ==
Provider -> SDK: 调用 registerInstance()
SDK -> Server: HTTP POST /nacos/v1/ns/instance\n(服务名、IP、端口、元数据)
Server -> Server: 1. 校验请求\n2. 存储实例到注册表\n3. 标记为"健康"
Server --> SDK: 返回注册成功 (200 OK)
SDK --> Provider: 注册完成回调

== 2. 心跳保活机制 ==
note over SDK, Server: 客户端每5秒发送心跳，证明服务存活
loop 每5秒执行
  SDK -> Server: HTTP PUT /nacos/v1/ns/instance/beat\n(实例唯一标识)
  Server -> Server: 1. 更新心跳时间\n2. 15秒未收到→标记"不健康"\n3. 30秒未收到→剔除实例
  Server --> SDK: 返回心跳确认
end

== 3. 服务订阅流程 ==
Consumer -> SDK: 调用 subscribe(serviceName, listener)
SDK -> Server: HTTP GET /nacos/v1/ns/instance/list\n(拉取初始实例列表)
Server --> SDK: 返回实例列表 + MD5哈希值
SDK -> SDK: 1. 缓存到本地内存\n2. 注册订阅关系
SDK --> Consumer: 订阅成功，返回初始实例

== 4. 实例变更推送（推拉结合） ==
note over Server, SDK: 推模式（实时）+ 拉模式（校验）
Server -> Server: 检测到实例变化（如下线）
Server --> SDK: 主动推送变更 (HTTP/UDP) 【推模式】
SDK -> SDK: 1. 更新本地缓存\n2. 计算新MD5
SDK --> Consumer: 触发 listener 回调（新实例列表）

loop 每10秒执行 【拉模式校验】
  SDK -> Server: HTTP GET /nacos/v1/ns/instance/list\n(携带本地MD5)
  Server -> Server: 对比MD5判断是否变更
  alt 有变更
    Server --> SDK: 返回新实例列表 + 新MD5
    SDK -> SDK: 更新缓存
    SDK --> Consumer: 触发 listener 回调
  else 无变更
    Server --> SDK: 返回 304 Not Modified
  end
end
@enduml

Demo - Js

服务注册:

const { NacosNamingClient } = require('nacos');
const http = require('http');

// Nacos 连接信息
const nacosHost = '192.168.1.3';
const nacosPort = 8848;

// 实例化 Nacos 命名服务客户端
const nacosClient = new NacosNamingClient({
    logger: console,
  serverList: `${nacosHost}:${nacosPort}`,
  namespace: 'public', // 默认命名空间
});

// 服务信息
const serviceName = 'nodejs-sdk-service';
const serviceIp = '127.0.0.1';
const servicePort = 3000;

// 服务启动
const server = http.createServer((req, res) => {
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end(`Hello from ${serviceName} on port ${servicePort}`);
});

server.listen(servicePort, async () => {
  console.log(`Service provider started at http://${serviceIp}:${servicePort}`);
  try {
    // 注册服务
    await nacosClient.ready();
    await nacosClient.registerInstance(serviceName, {
      ip: serviceIp,
      port: servicePort,
      // 也可以添加其他元数据
      metadata: {
        env: 'production'
      }
    });
    console.log(`Service '${serviceName}' registered to Nacos.`);
  } catch (error) {
    console.error('Failed to register service:', error);
  }
});

// 优雅停机处理，确保服务注销
process.on('SIGINT', async () => {
  try {
    console.log(`\nStopping service provider...`);
    await nacosClient.deregisterInstance(serviceName, {
      ip: serviceIp,
      port: servicePort,
    });
    console.log(`Service '${serviceName}' deregistered from Nacos.`);
    process.exit(0);
  } catch (error) {
    console.error('Failed to deregister service:', error);
    process.exit(1);
  }
});

消费者服务发现

const { NacosNamingClient } = require('nacos');
const http = require('http');

// Nacos 连接信息
const nacosHost = '192.168.1.3';
const nacosPort = 8848;

const nacosClient = new NacosNamingClient({
    logger: console,
    serverList: `${nacosHost}:${nacosPort}`,
    namespace: 'public', // 默认命名空间
});

// 目标服务信息
const targetServiceName = 'nodejs-sdk-service';

async function consumeService() {
    try {
        await nacosClient.ready();

        // 获取服务实例列表
        const instances = await nacosClient.getAllInstances(targetServiceName);
        if (!instances || instances.length === 0) {
            console.log(`No instances of '${targetServiceName}' found.`);
            return;
        }

        // 随机选择一个健康的实例
        const healthyInstances = instances.filter(instance => instance.healthy);
        if (healthyInstances.length === 0) {
            console.log(`No healthy instances of '${targetServiceName}' found.`);
            return;
        }

        const instance = healthyInstances[Math.floor(Math.random() * healthyInstances.length)];
        const { ip, port } = instance;

        console.log(`Found service instance: ${ip}:${port}. Calling...`);

        // 调用选定的服务实例
        http.get(`http://${ip}:${port}`, (res) => {
            let data = '';
            res.on('data', (chunk) => {
                data += chunk;
            });
            res.on('end', () => {
                console.log(`Response from service: ${data}`);
            });
        }).on('error', (err) => {
            console.error('Failed to call service:', err.message);
        });

    } catch (error) {
        console.error('Failed to get service instances:', error);
    }
}

// 每隔 5 秒调用一次服务
setInterval(consumeService, 5000);
console.log(`Starting service consumer for '${targetServiceName}'.`);

动态配置

@startuml Nacos 配置变更与推送原理
' 参与者定义
actor 配置管理员Admin as Admin
participant "Nacos 控制台" as Console
participant "Nacos 服务器" as Server
participant "Nacos Clinet SDK" as SDK
actor 业务应用Application as App

' 样式定义
skinparam participant {
  BackgroundColor #f0f8ff
  BorderColor #2c3e50
}
skinparam actor {
  BackgroundColor #e8f4fd
  BorderColor #2980b9
}
skinparam note {
  BackgroundColor #fff3cd
  BorderColor #f39c12
}

== 1. 初始配置拉取 ==
App -> SDK: 调用 getConfig(dataId, group)
SDK -> SDK: 检查本地缓存\n(路径：${user.home}/nacos/config)
alt 缓存有效
  SDK --> App: 返回本地缓存配置
else 缓存无效/不存在
  SDK -> Server: HTTP GET /nacos/v1/cs/configs\n(携带dataId、group)
  Server -> Server: 1. 查询配置\n2. 计算MD5
  Server --> SDK: 返回配置内容 + MD5
  SDK -> SDK: 1. 更新本地文件缓存\n2. 记录MD5
  SDK --> App: 返回最新配置
end

== 2. 配置监听（长轮询核心） ==
App -> SDK: 调用 addListener(dataId, listener)
SDK -> Server: 长轮询请求\nHTTP GET /nacos/v1/cs/configs/listener\n(超时30秒，携带本地MD5)
note over SDK, Server: 长轮询：请求挂起，等待变更或超时

== 3. 配置变更触发 ==
Admin -> Console: 控制台修改并发布配置
Console -> Server: HTTP POST /nacos/v1/cs/configs\n(提交新配置)
Server -> Server: 1. 更新配置存储\n2. 计算新MD5\n3. 标记"已变更"
Server --> Console: 返回发布成功

== 4. 变更推送与处理 ==
Server -> SDK: 长轮询响应（返回变更的dataId）
SDK -> Server: 拉取新配置\nHTTP GET /nacos/v1/cs/configs\n(携带dataId、group)
Server --> SDK: 返回新配置 + 新MD5
SDK -> SDK: 1. 更新本地缓存\n2. 对比MD5确认变更
SDK --> App: 触发 listener 回调（返回新配置）

' 持续监听循环
SDK -> Server: 立即发起下一次长轮询
note over SDK, Server: 循环长轮询，保持实时监听
@enduml