改变eureka server中注册的服务的健康检测方式

悠悠 2022-05-25 13:56 202阅读 0赞

默认情况下注册到eureka server的服务是通过心跳来告知自己是UP还是DOWN，并不是通过spring-boot-actuator模块的/health端点来实现的，这样其实不是很合理。

默认的心跳实现方式可以有效的检查eureka客户端进程是否正常运作，但是无法保证客户端应用能够正常提供服务。由于大多数微服务应用都会有一些其他的外部资源依赖，比如数据库，REDIS缓存等，如果我们的应用与这些外部资源无法连通的时候，实际上已经不能提供正常的对外服务了，但因为客户端心跳依然在运行，所以它还是会被服务消费者调用，而这样的调用实际上并不能获得预期的后果。

我们可以通过在eureka客户端中配置:eureka.client.healthcheck.enabled=true，就可以改变eureka server对客户端健康检测的方式，改用actuator的/health端点来检测。

我们在前面的ribbon consumer样例工程中添加一个自定义的HealthIndicator:

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1.  **package** com.example.eurekaclientconsumerribbon.health;  
2.    
3.  **import** org.springframework.boot.actuate.health.Health;  
4.  **import** org.springframework.boot.actuate.health.HealthIndicator;  
5.  **import** org.springframework.stereotype.Component;  
6.    
7.  @Component  
8.  **public** **class** MyHealthChecker **implements** HealthIndicator \{  
9.    
10.   
11.     **private** **boolean** up = **true**;  
12.   
13.     @Override  
14.     **public** Health health() \{  
15.         **if** (up) \{  
16.             **return** **new** Health.Builder().withDetail("aaa\_cnt", 10) //自定义监控内容  
17.                     .withDetail("bbb\_status", "up").up().build();  
18.         \} **else** \{  
19.             **return** **new** Health.Builder().withDetail("error", "client is down").down().build();  
20.         \}  
21.   
22.     \}  
23.   
24.     **public** **boolean** isUp() \{  
25.         **return** up;  
26.     \}  
27.   
28.     **public** **void** setUp(**boolean** up) \{  
29.         **this**.up = up;  
30.     \}  
31. \}

里面有一个成员变量up，用来控制是否监控，下面我们会在请求中改变这个变量的值来模拟健康状态UP->DOWN

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1.  **package** com.example.eurekaclientconsumerribbon.controller;  
2.    
3.  **import** com.example.eurekaclientconsumerribbon.health.MyHealthChecker;  
4.  **import** org.springframework.beans.factory.annotation.Autowired;  
5.  **import** org.springframework.web.bind.annotation.RequestMapping;  
6.  **import** org.springframework.web.bind.annotation.RequestParam;  
7.  **import** org.springframework.web.bind.annotation.RestController;  
8.    
9.  @RestController  
10. **public** **class** UpController \{  
11.   
12.     @Autowired  
13.     MyHealthChecker myHealthChecker;  
14.   
15.     @RequestMapping("/up")  
16.     **public** String up(@RequestParam("up") Boolean up) \{  
17.         myHealthChecker.setUp(up);  
18.   
19.         **return** up.toString();  
20.     \}  
21.   
22.   
23.   
24. \}

application.yml:

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1.  spring:  
2.    application:  
3.      name: eureka-client-consumer-ribbon  
4.  management:  
5.    security:  
6.      enabled: **false**  
7.  \---  
8.  spring:  
9.    profiles: peer1  
10. server:  
11.   port: 8200  
12. eureka:  
13.   client:  
14.     serviceUrl:  
15.       defaultZone: http://peer1:8001/eureka/,http://peer2:8002/eureka/  
16.     healthcheck:  
17.           enabled: **true** \#使用health端点来代替心跳表明服务是否可用，反应到eureka server ui上服务的UP还是DOWN  
18.   instance:  
19.     hostname: peer1  
20. \#    instanceId: $\{spring.application.name\}:$\{vcap.application.instance\_id:$\{spring.application.instance\_id:$\{random.value\}\}\}  
21.   
22. \---  
23. spring:  
24.   profiles: peer2  
25. server:  
26.   port: 8201  
27. eureka:  
28.   client:  
29.     serviceUrl:  
30.       defaultZone: http://peer1:8001/eureka/,http://peer2:8002/eureka/  
31.   instance:  
32.     hostname: peer2  
33. \#    instanceId: $\{spring.application.name\}:$\{vcap.application.instance\_id:$\{spring.application.instance\_id:$\{random.value\}\}\}

主要看配置里面设置了eureka.client.healthcheck.enabled=true，这个配置属性在IDEA里面不会自动提示，我一度怀疑写错了，试过确实有效的改变了检测方式。

启动类:

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1.  **package** com.example.eurekaclientconsumerribbon;  
2.    
3.  **import** org.springframework.boot.SpringApplication;  
4.  **import** org.springframework.boot.autoconfigure.SpringBootApplication;  
5.  **import** org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;  
6.  **import** org.springframework.cloud.client.loadbalancer.LoadBalanced;  
7.  **import** org.springframework.cloud.netflix.eureka.EnableEurekaClient;  
8.  **import** org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;  
9.  **import** org.springframework.context.annotation.Bean;  
10. **import** org.springframework.web.client.RestTemplate;  
11.   
12. @SpringBootApplication  
13. @EnableEurekaClient  
14. @EnableCircuitBreaker  
15. @EnableHystrixDashboard  
16. **public** **class** EurekaClientConsumerRibbonApplication \{  
17.   
18.   
19.     @LoadBalanced  
20.     @Bean  
21.     RestTemplate restTemplate() \{  
22.         **return** **new** RestTemplate();  
23.     \}  
24.   
25.   
26.   
27.   
28.     **public** **static** **void** main(String\[\] args) \{  
29.         SpringApplication.run(EurekaClientConsumerRibbonApplication.**class**, args);  
30.     \}  
31. \}

pom:

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1.  <?xml version="1.0" encoding="UTF-8"?>  
2.  <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
3.      xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">  
4.      <modelVersion>4.0.0</modelVersion>  
5.    
6.      <groupId>com.example</groupId>  
7.      <artifactId>eureka-client-consumer-ribbon</artifactId>  
8.      <version>0.0.1\-SNAPSHOT</version>  
9.      <packaging>jar</packaging>  
10.   
11.     <name>eureka-client-consumer-ribbon</name>  
12.     <description>Demo project **for** Spring Boot</description>  
13.   
14.     <parent>  
15.         <groupId>org.springframework.boot</groupId>  
16.         <artifactId>spring-boot-starter-parent</artifactId>  
17.         <version>1.5.6.RELEASE</version>  
18.         <relativePath/>   
19.     </parent>  
20.   
21.     <properties>  
22.         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>  
23.         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>  
24.         <java.version>1.8</java.version>  
25.         <spring-cloud.version>Dalston.SR3</spring-cloud.version>  
26.     </properties>  
27.   
28.     <dependencies>  
29.         <dependency>  
30.             <groupId>org.springframework.cloud</groupId>  
31.             <artifactId>spring-cloud-starter-eureka</artifactId>  
32.         </dependency>  
33.         <dependency>  
34.             <groupId>org.jolokia</groupId>  
35.             <artifactId>jolokia-core</artifactId>  
36.         </dependency>  
37.         <dependency>  
38.             <groupId>org.springframework.cloud</groupId>  
39.             <artifactId>spring-cloud-starter-ribbon</artifactId>  
40.         </dependency>  
41.         <dependency>  
42.             <groupId>org.springframework.cloud</groupId>  
43.             <artifactId>spring-cloud-starter-hystrix</artifactId>  
44.         </dependency>  
45.         <dependency>  
46.             <groupId>org.springframework.cloud</groupId>  
47.             <artifactId>spring-cloud-starter-hystrix-dashboard</artifactId>  
48.         </dependency>  
49.         <dependency>  
50.             <groupId>org.springframework.boot</groupId>  
51.             <artifactId>spring-boot-starter-actuator</artifactId>  
52.         </dependency>  
53.         <dependency>  
54.             <groupId>org.springframework.boot</groupId>  
55.             <artifactId>spring-boot-starter-test</artifactId>  
56.             <scope>test</scope>  
57.         </dependency>  
58.     </dependencies>  
59.   
60.     <dependencyManagement>  
61.         <dependencies>  
62.             <dependency>  
63.                 <groupId>org.springframework.cloud</groupId>  
64.                 <artifactId>spring-cloud-dependencies</artifactId>  
65.                 <version>$\{spring-cloud.version\}</version>  
66.                 <type>pom</type>  
67.                 <scope>**import**</scope>  
68.             </dependency>  
69.         </dependencies>  
70.     </dependencyManagement>  
71.   
72.     <build>  
73.         <plugins>  
74.             <plugin>  
75.                 <groupId>org.springframework.boot</groupId>  
76.                 <artifactId>spring-boot-maven-plugin</artifactId>  
77.                 <executions>  
78.                     <execution>  
79.                         <goals>  
80.                             <goal>build-info</goal>  
81.                         </goals>  
82.                     </execution>  
83.                 </executions>  
84.             </plugin>  
85.         </plugins>  
86.     </build>  
87.   
88.   
89. </project>

启动该服务将会注册到eureka server中去，此时显示的应该是UP

![Center][]

然后我们调用一下服务:http://localhost:8200/up?up=false，将此时查看http://localhost:8200/health,整个应用的health状态变成DOWN了：

![Center 1][]

注册中心的服务状态也将变为DOWN：

![Center 2][]

我们可以试一下把application.yml中eureka.client.healthcheck.enabled=true这段配置去掉重新启动服务，然后调用服务将health变为DOWN,但是注册中心中仍然会显示该服务的status为UP！

[view plain]: https://blog.csdn.net/xiao_jun_0820/article/details/77991963#
[Center]: /images/20220525/a2de7707dd8349499e80f1c0f04d698c.png
[Center 1]: /images/20220525/89563af156eb4ad3bd8f95e25c290ca1.png
[Center 2]: /images/20220525/93a5837a6b824f05a47a548742107a6a.png