SpringCloud基本特性

• 分布式配置中心

• 服務注冊/發現(Eureka)

• 智能路由（Zuul）

• 服務間的調用

• 客戶端負載均衡（Ribbon）

• 斷路器（Hystrix）

• 分布式消息管理

---

demo結構

服務發現:Eureka客戶端

Eureka is the Netflix Service Discovery Server and Client. The server can be configured and deployed to be highly available, with each server replicating state about the registered services to the others

Eureka是Netflix服務發現的一種服務和客戶端。這種服務是可以被高可用性配置的和部署,并且在注冊的服務當中，每個服務的狀態可以互相復制給彼此

開啟Eureka

@EnableEurekaServer //注冊服務器中心
@SpringBootApplication
public class SpringcloudDemoApplication {
 public static void main(String[] args) {
   SpringApplication.run(SpringcloudDemoApplication.class, args);
 }
}

---

application.properties

#SpringCloud - Eureka Configuration
server.port=1111
eureka.client.register-with-eureka=false
eureka.client.fetch-registry=false
# "defaultZone" is a magic string fallback value that provides the service URL for any client that doesn’t express a preference
# "defaultZone"是一個神奇的字符串回退值，它提供了服務的URL給任何客戶端，而這不意味優先級
eureka.client.serviceUrl.defaultZone=http://localhost:${server.port}/eureka/

訪問

http://localhost:1111/

---

注冊到Eureka

Eureka receives heartbeat messages from each instance belonging to a service. If the heartbeat fails over a configurable timetable, the instance is normally removed from the registry.

Eureka通過一個服務從各個實例接收心跳信息。如果心跳接收失敗超過配置的時間，實例將會正常從注冊里面移除。

@EnableEurekaServer //注冊服務器中心
@EnableDiscoveryClient //**Eureka中的DiscoveryClient實現，才能實現Controller中對服務信息的輸出。
@SpringBootApplication
public class SpringcloudServiceApplication {

    public static void main(String[] args) {
    SpringApplication.run(SpringcloudServiceApplication.class, args);
    }
}

---

@RestController
public class ComputeController {

    private final Logger logger = Logger.getLogger(getClass());

    /**通過DiscoveryClient對象，在日志中打印出服務實例的相關內容*/
    @Autowired
    private DiscoveryClient client;

    @RequestMapping(value = "/add" ,method = RequestMethod.GET)
    public Integer add(@RequestParam Integer a, @RequestParam Integer b) {
        ServiceInstance instance = client.getLocalServiceInstance();
        Integer r = a + b;
        logger.info("/add, host:" + instance.getHost() + ", service_id:" + instance.getServiceId() + ", result:" + r);
        return r;
    }

}

---

spring.application.name=compute-service
server.port=2222
eureka.client.serviceUrl.defaultZone=http://localhost:1111/eureka/

訪問

http://localhost:2222/add?a=1&b=2

---

• @EnableEurekaClient
  
  • 聲明Eureka注冊服務(etc.實例的行為由eureka.instance.*的配置項來決定,但是你最好確保你的spring.application.name有個默認值)
• @EnableDiscoveryClient
  
  • 定位發現Eureka客戶端

---

eureka 客戶端官方例子

@Configuration
@ComponentScan
@EnableAutoConfiguration
@EnableEurekaClient
@RestController
public class Application {

    @RequestMapping("/")
    public String home() {
        return "Hello world";
    }

    public static void main(String[] args) {
        new SpringApplicationBuilder(Application.class).web(true).run(args);
    }

}

更多配置請查看 EurekaInstanceConfigBean 和 EurekaClientConfigBean

---

Eureka服務的身份驗證

HTTP basic authentication will be automatically added to your eureka client if one of the eureka.client.serviceUrl.defaultZone URLs has credentials embedded in it

如果其中一個eureka.client.serviceUrl.defaultZone的url已經把憑證嵌入到它里面，那么HTTP基本的身份驗證將會被自動添加到你的eureka客戶端

For more complex needs you can create a @Bean of type DiscoveryClientOptionalArgs and inject ClientFilter instances into it, all of which will be applied to the calls from the client to the server

對于更復雜的需求，您可以創建一個帶“@Bean”注解的“DiscoveryClientOptionalArgs”類型并且為它注入“ClientFilter”實例

**由于Eureka的限制，Eureka不支持單節點身份驗證。

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

---

#security.basic.enabled=true
#fail
#user.name=admin    
#user.password=123

---

健康指標和狀態頁面

Springboot監控
Springboot-admin

官網

eureka.instance.statusPageUrlPath=${management.context-path}/info
eureka.instance.healthCheckUrlPath=${management.context-path}/health

---

---

        <!-- Springboot監控 -->
        <dependency>
            <groupId>de.codecentric</groupId>
            <artifactId>spring-boot-admin-server</artifactId>
             <version>1.4.2</version>
        </dependency>
        <dependency>
            <groupId>de.codecentric</groupId>
            <artifactId>spring-boot-admin-server-ui</artifactId>
            <version>1.4.2</version>
        </dependency>

---

@EnableAdminServer //開啟服務監控

---

spring.boot.admin.url=http://localhost:${server.port}
spring.jackson.serialization.indent_output=true
endpoints.health.sensitive=false

---

http://localhost:1111/metrics
http://localhost:1111/health

springcloud中文文檔