SpringCloud註冊與發現元件eureka使用
它主要包括兩個元件：Eureka Server 和 Eureka Client
- Eureka Client：一個Java客戶端，用於簡化與 Eureka Server 的互動（通常就是微服務中的客戶端和服務端）
- Eureka Server：提供服務註冊和發現的能力（通常就是微服務中的註冊中心）
工作結構圖：
各個微服務啟動時，會通過 Eureka Client 向 Eureka Server 註冊自己，Eureka Server 會儲存該服務的資訊
也就是說，每個微服務的客戶端和服務端，都會註冊到 Eureka Server，這就衍生出了微服務相互識別的話題
- 同步：每個 Eureka Server 同時也是 Eureka Client（邏輯上的）
多個 Eureka Server 之間通過複製的方式完成服務登錄檔的同步，形成 Eureka 的高可用 - 識別：Eureka Client 會快取 Eureka Server 中的資訊
即使所有 Eureka Server 節點都宕掉，服務消費者仍可使用快取中的資訊找到服務提供者（筆者已親測） - 續約：微服務會週期性（預設30s）地向 Eureka Server 傳送心跳以Renew（續約）資訊（類似於heartbeat）
- 續期：Eureka Server 會定期（預設60s）執行一次失效服務檢測功能
它會檢查超過一定時間（預設90s）沒有Renew的微服務，發現則會登出該微服務節點
Spring Cloud 已經把 Eureka 整合在其子專案 Spring Cloud Netflix 裡面
Eureka Server在springCloud整合
1.pom檔案配置
<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 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>com.itmuch.cloud</groupId> <artifactId>microservice-spring-cloud</artifactId> <version>0.0.1-SNAPSHOT</version> </parent> <artifactId>microservice-discovery-eureka</artifactId> <packaging>jar</packaging> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-eureka-server</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> </dependency> </dependencies> </project>
<dependencies>
<dependency><!--eureka-server註冊與發現依賴-->
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka-server</artifactId>
</dependency>
<dependency><!--eureka-server安全管理依賴，例如使用者名稱，密碼登入-->
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-security</artifactId>
</dependency>
</dependencies>
2 yml配置檔案
security:
basic:
enabled: true
user:
name: user
password: password123
server:
port: 8761
eureka:
client:
register-with-eureka: false
fetch-registry: false
service-url:
defaultZone: http://user:password123@localhost:8761/eureka3.啟動類
package com.itmuch.cloud;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
@SpringBootApplication
@EnableEurekaServer
public class EurekaApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaApplication.class, args);
}
}
SpringCloud 整合Eureka client
1.pom檔案
<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>microservice-provider-user</artifactId>
<packaging>jar</packaging>
<name>microservice-provider-user</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>com.itmuch.cloud</groupId>
<artifactId>microservice-spring-cloud</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
</dependencies>
</project>
<dependency><!--客戶端依賴-->
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<dependency><!--運維監控瀏覽器檢視依賴-->
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
2.yml配置檔案
server:
port: 7900
spring:
jpa:
generate-ddl: false
show-sql: true
hibernate:
ddl-auto: none
datasource:
platform: h2
schema: classpath:schema.sql
data: classpath:data.sql
application:
name: microservice-provider-user
logging:
level:
root: INFO
org.hibernate: INFO
org.hibernate.type.descriptor.sql.BasicBinder: TRACE
org.hibernate.type.descriptor.sql.BasicExtractor: TRACE
com.itmuch: DEBUG
eureka:
client:
healthcheck:
enabled: true
serviceUrl:
defaultZone: http://user:password123@localhost:8761/eureka
instance:
prefer-ip-address: true
instance-id: ${spring.application.name}:${spring.cloud.client.ipAddress}:${spring.application.instance_id:${server.port}}
metadata-map:
zone: ABC # eureka可以理解的元資料
lilizhou: BBC # 不會影響客戶端行為
lease-renewal-interval-in-seconds: 53.啟動客戶端類
package com.itmuch.cloud;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
@SpringBootApplication
@EnableEurekaClient
public class MicroserviceSimpleProviderUserApplication {
public static void main(String[] args) {
SpringApplication.run(MicroserviceSimpleProviderUserApplication.class, args);
}
}