Spring Cloud Alibaba

[Spring Cloud Alibaba] 4 Start a Provider Application

Sample illustrates how to register a service to Nacos...

Posted by Mr.Vincent on 2021-05-26
Estimated Reading Time 12 Minutes
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概述

通过一个简单的示例来感受一下如何将服务注册到 Nacos，其实和 Eureka 没有太大差别。

案例

POM

创建一个工程名为 hello-spring-cloud-alibaba-nacos-provider 的服务提供者项目，pom.xml 配置如下：

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<?xml version="1.0" encoding="UTF-8"?>
<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>
    <parent>
        <groupId>com.example</groupId>
        <artifactId>hello-spring-cloud-alibaba</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>

    <artifactId>hello-spring-cloud-alibaba-nacos-provider</artifactId>
    <packaging>jar</packaging>

    <name>hello-spring-cloud-alibaba-nacos-provider</name>
    <version>${parent.version}</version>
    <url>https://v-vincen.life</url>
    <inceptionYear>2021-Now</inceptionYear>
    <description>Demo project for Nacos Provider</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <!-- Spring Boot Begin -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!-- Spring Boot End -->

        <!-- Spring Cloud Alibaba Begin -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <!-- Spring Cloud Alibaba End -->
    </dependencies>

    <build>
        <finalName>${project.artifactId}</finalName>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

Application、Controller

通过 @EnableDiscoveryClient 注解表明是一个 Nacos 客户端，该注解是 Spring Cloud 提供的原生注解。

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/**
 * @author vincent 
 */
@SpringBootApplication
@EnableDiscoveryClient
public class HelloSpringCloudAlibabaNacosProviderApplication {
    public static void main(String[] args) {
        SpringApplication.run(HelloSpringCloudAlibabaNacosProviderApplication.class, args);
    }
}
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/**
 * @author vincent
 */
@RestController
public class NacosProviderController {
    @Autowired
    private DiscoveryClient discoveryClient;

    @Value("${spring.application.name}")
    private String serviceId;

    @GetMapping(value = "/instances")
    public List<ServiceInstance> instances() {
        return discoveryClient.getInstances(serviceId);
    }

    @GetMapping(value = "/echo/{message}")
    public String echo(@PathVariable String message) {
        return "Hello Nacos Discovery " + message;
    }
}

application.yml

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spring:
  application:
    name: nacos-provider
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848

server:
  port: 8081

management:
  endpoints:
    web:
      exposure:
        include: "*"

启动工程

通过浏览器访问 http://localhost:8848/nacos，即 Nacos Server 网址。

nacos_server

你会发现一个服务已经注册在服务中了，服务名为 nacos-provider。这时访问地址 http://localhost:8081/echo/hi ，你会在浏览器上看到：

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Hello Nacos Discovery hi

访问地址 http://localhost:8081/instances ，你会在浏览器上看到：

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[
  {
    "serviceId": "nacos-provider",
    "host": "192.168.0.138",
    "port": 8081,
    "secure": false,
    "metadata": {
      "nacos.instanceId": "192.168.0.138#8081#DEFAULT#DEFAULT_GROUP@@nacos-provider",
      "nacos.weight": "1.0",
      "nacos.cluster": "DEFAULT",
      "nacos.ephemeral": "true",
      "nacos.healthy": "true",
      "preserved.register.source": "SPRING_CLOUD"
    },
    "uri": "http://192.168.0.138:8081",
    "instanceId": null,
    "scheme": null
  }
]

服务的端点检查

Actuator endpoints 可以让我们监控和与我们的应用（application）交互。Spring Boot actuator 包含了大量的内置 endpoints， 当然，我们也可以添加我们自己的。如何暴露端口取决与你采用的技术。大多数应用采用 HTTP 监控，这时 endpoint 的 ID 就映射为一个接口 URL。通过访问 http://ip:port/actuator，我们可以看到其自带内置的全部 endpoint。

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{
  "_links": {
    "self": {
      "href": "http://localhost:8081/actuator",
      "templated": false
    },
    "threaddump": {
      "href": "http://localhost:8081/actuator/threaddump",
      "templated": false
    },
    "mappings": {
      "href": "http://localhost:8081/actuator/mappings",
      "templated": false
    },
    "info": {
      "href": "http://localhost:8081/actuator/info",
      "templated": false
    },
    "health-path": {
      "href": "http://localhost:8081/actuator/health/{*path}",
      "templated": true
    },
    "health": {
      "href": "http://localhost:8081/actuator/health",
      "templated": false
    },
    "loggers-name": {
      "href": "http://localhost:8081/actuator/loggers/{name}",
      "templated": true
    },
    "loggers": {
      "href": "http://localhost:8081/actuator/loggers",
      "templated": false
    },
    "caches-cache": {
      "href": "http://localhost:8081/actuator/caches/{cache}",
      "templated": true
    },
    "caches": {
      "href": "http://localhost:8081/actuator/caches",
      "templated": false
    },
    "beans": {
      "href": "http://localhost:8081/actuator/beans",
      "templated": false
    },
    "configprops": {
      "href": "http://localhost:8081/actuator/configprops",
      "templated": false
    },
    "env": {
      "href": "http://localhost:8081/actuator/env",
      "templated": false
    },
    "env-toMatch": {
      "href": "http://localhost:8081/actuator/env/{toMatch}",
      "templated": true
    },
    "refresh": {
      "href": "http://localhost:8081/actuator/refresh",
      "templated": false
    },
    "serviceregistry": {
      "href": "http://localhost:8081/actuator/serviceregistry",
      "templated": false
    },
    "features": {
      "href": "http://localhost:8081/actuator/features",
      "templated": false
    },
    "conditions": {
      "href": "http://localhost:8081/actuator/conditions",
      "templated": false
    },
    "heapdump": {
      "href": "http://localhost:8081/actuator/heapdump",
      "templated": false
    },
    "nacosdiscovery": {
      "href": "http://localhost:8081/actuator/nacosdiscovery",
      "templated": false
    },
    "scheduledtasks": {
      "href": "http://localhost:8081/actuator/scheduledtasks",
      "templated": false
    },
    "metrics-requiredMetricName": {
      "href": "http://localhost:8081/actuator/metrics/{requiredMetricName}",
      "templated": true
    },
    "metrics": {
      "href": "http://localhost:8081/actuator/metrics",
      "templated": false
    }
  }
}

具体详情，这里不做过多叙述，有兴趣的可自行查看官网。

本文中，主要讲述 spring-cloud-starter-alibaba-nacos-discovery 的使用，Actuator 也提供了一个 EndPoint, EndPoint 的访问地址为 http://ip:port/actuator/nacosdiscovery。 主要提供了两类信息：

  • subscribe：显示了当前有哪些服务订阅者。
  • NacosDiscoveryProperties：显示了当前服务实例关于 Nacos 的基础配置。

通过浏览器访问 http://localhost:8081/actuator/nacosdiscovery 你会在浏览器上看到：

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{
  "subscribe": [
    {
      "name": "nacos-provider",
      "groupName": "DEFAULT_GROUP",
      "clusters": "DEFAULT",
      "cacheMillis": 1000,
      "hosts": [
        {
          "instanceId": "192.168.0.138#8081#DEFAULT#DEFAULT_GROUP@@nacos-provider",
          "ip": "192.168.0.138",
          "port": 8081,
          "weight": 1.0,
          "healthy": true,
          "enabled": true,
          "ephemeral": true,
          "clusterName": "DEFAULT",
          "serviceName": "DEFAULT_GROUP@@nacos-provider",
          "metadata": {
            "preserved.register.source": "SPRING_CLOUD"
          },
          "instanceHeartBeatInterval": 5000,
          "instanceHeartBeatTimeOut": 15000,
          "ipDeleteTimeout": 30000
        }
      ],
      "lastRefTime": 0,
      "checksum": "",
      "allIPs": false,
      "valid": true
    }
  ],
  "NacosDiscoveryProperties": {
    "serverAddr": "127.0.0.1:8848",
    "username": "",
    "password": "",
    "endpoint": "",
    "namespace": "",
    "watchDelay": 30000,
    "logName": "",
    "service": "nacos-provider",
    "weight": 1.0,
    "clusterName": "DEFAULT",
    "group": "DEFAULT_GROUP",
    "namingLoadCacheAtStart": "false",
    "metadata": {
      "preserved.register.source": "SPRING_CLOUD"
    },
    "registerEnabled": true,
    "ip": "192.168.0.138",
    "networkInterface": "",
    "port": 8081,
    "secure": false,
    "accessKey": "",
    "secretKey": "",
    "heartBeatInterval": null,
    "heartBeatTimeout": null,
    "ipDeleteTimeout": null,
    "instanceEnabled": true,
    "ephemeral": true,
    "nacosProperties": {
      "secretKey": "",
      "namespace": "",
      "username": "",
      "namingLoadCacheAtStart": "false",
      "serverAddr": "127.0.0.1:8848",
      "com.alibaba.nacos.naming.log.filename": "",
      "clusterName": "DEFAULT",
      "password": "",
      "accessKey": "",
      "endpoint": ""
    }
  }
}

关于 Nacos Discovery Starter 更多的配置项信息

配置项 Key 默认值 说明
服务端地址 spring.cloud .nacos.discovery .server-addr Nacos Server 启动监听的ip地址和端口
服务名 spring.cloud .nacos.discovery .service ${spring.application.name} 注册的服务名
权重 spring.cloud .nacos.discovery .weight 1 取值范围 1 到 100，数值越大，权重越大
网卡名 spring.cloud .nacos.discovery .network-interface 当IP未配置时，注册的IP为此网卡所对应的IP地址，如果此项也未配置，则默认取第一块网卡的地址
注册的IP地址 spring.cloud .nacos.discovery .ip 优先级最高
注册的端口 spring.cloud .nacos.discovery .port -1 默认情况下不用配置，会自动探测
命名空间 spring.cloud .nacos.discovery .namespace 常用场景之一是不同环境的注册的区分隔离，例如开发测试环境和生产环境的资源（如配置、服务）隔离等
AccessKey spring.cloud .nacos.discovery .access-key 当要上阿里云时，阿里云上面的一个云账号名
SecretKey spring.cloud .nacos.discovery .secret-key 当要上阿里云时，阿里云上面的一个云账号密码
Metadata spring.cloud .nacos.discovery .metadata 使用Map格式配置，用户可以根据自己的需要自定义一些和服务相关的元数据信息
日志文件名 spring.cloud .nacos.discovery .log-name
集群 spring.cloud .nacos.discovery .cluster-name DEFAULT Nacos集群名称
接入点 spring.cloud .nacos.discovery .endpoint 地域的某个服务的入口域名，通过此域名可以动态地拿到服务端地址
是否集成Ribbon ribbon.nacos .enabled true 一般都设置成true即可
是否开启Nacos Watch spring.cloud .nacos.discovery .watch.enabled true 可以设置成false来关闭 watch

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