Springclub02 Eureka registry

2、 Registry

1. Introduction to Eureka

Eureka is the core service of microservice system
Role: registration and discovery
To start all services, you need to register your address in the registry; to call other services, you need to get the registry from the registry to find other services.
Service ID
Host address
item-service—localhost:8001
user-service—localhost:8101
order-service—localhost:8201

2. The working mechanism of Eureka:

• register

  • When the service provider starts, it will repeatedly try to register with Eureka until the registration is successful

• Pull

  • Consumers pull the registry every 30 seconds to refresh it

• heartbeat

  • The service provider sends heartbeat data to Eureka every 30 seconds
  • If the Eureka server fails to receive the heartbeat of a service three times in a row, it will delete the registration information of the service

• Self protection model

  • If the network is unstable, 85% of servers have abnormal heartbeat within 15 minutes, they will automatically enter the self-protection mode
  • All registration information will not be deleted
  • After the network is restored, it can automatically exit the protection mode and return to normal
  • During development and debugging, protection mode can be disabled to avoid affecting the test

3. Build Eureka server

3.1 create eurekaserver project

3.2 editing pom.xml

<?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>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>cn.tedu</groupId>
    <artifactId>sp05-eureka</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>sp05-eureka</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.RELEASE</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

3.3 modification application.yml

First of all application.propertie Change to application.yml

spring:
  application:
    name: eureka-server
    
server:
  port: 2001
  
eureka:
  server:
    enable-self-preservation: false
  instance:
    hostname: eureka1
  client:
    register-with-eureka: false
    fetch-registry: false

• Between Eureka cluster servers, throughhostnameTo distinguish
• eureka.server.enable-self-preservation
  Eureka’s self-protection status: whether the rate of heartbeat failure exceeds 85% within 15 minutes. If it exceeds 85%, Eureka server will protect the current instance registration information and prompt a warning. Once it enters the protection mode, Eureka server will try to protect the information in its service registry and will not delete the data in the service registry. That is, no micro services will be logged off
• eureka.client.register-with-eureka=false
  Do not register with yourself
• eureka.client.fetch-registry=false
  Do not pull registration information from itself
• eureka.instance.lease-expiration-duration-in-seconds
  After the last heartbeat, how long does it take to determine that the microservice is not available? The default value is 90

3.4 modify main program

---

• add to@EnableEurekaServer

package cn.tedu.sp05;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
@EnableEurekaServer
@SpringBootApplication
public class Sp05EurekaApplication {
    public static void main(String[] args) {
        SpringApplication.run(Sp05EurekaApplication.class, args);
    }
} 

3.4 modify hosts file and add Eureka domain name mapping

C:WindowsSystem32driversetchosts
Add content:

127.0.0.1       eureka1
127.0.0.1       eureka2` 

3.5 start and access the test

• http://eureka1:2001

4. Service provider

• Modify the item service, user service and order service to register the microservice with Eureka server

four point one pom.xml Add Eureka dependency

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>

four point two application.yml Add Eureka registration configuration

eureka:
  client:
    service-url:
      defaultZone: http://eureka1:2001/eureka

• eureka.instance.lease-renewal-interval-in-seconds
  Heartbeat interval, default 30 seconds
• The default zone, the default location, can be modified to a specific geographic location, such as Beijing, Shanghai, Shenzhen, etc., which indicates the deployment location of Eureka server and needs to be provided by the cloud server
• eureka.client.registry-fetch-interval-seconds
  The time interval for pulling registration information is 30 seconds by default

4.3 start the service and view the registration information in Eureka

• http://eureka1:2001

5. High availability of Eureka and “service provider”

5.1 high availability of item service

startup parameter--server.portYou can override the port configuration in YML

5.1.2 configure startup parameters

• item-service-8001

• item-service-8002

5.1.3 start up test

• Visit Eureka to view item service registration information

• Access two port test
  http://localhost:8001/35
  http://localhost:8002/35

5.2 Eureka high availability

5.2.1. Add profile configuration files of two servers

application-eureka1.yml

`eureka:
  instance:
    hostname: eureka1
  client:
    Register with Eureka: the configuration of true # profile will override the public configuration
    Fetch registry: the configuration of true # profile will override the public configuration
    service-url: 
      defaultZone:  http://eureka2 : 2002 / Eureka # register with eureka2 when eureka1 starts`

application-eureka2.yml

eureka:
  instance:
    hostname: eureka2
  client:
    Register with Eureka: the configuration of true # profile will override the public configuration
    Fetch registry: the configuration of true # profile will override the public configuration
    service-url: 
      defaultZone:  http://eureka1 : 2001 / Eureka # register with eureka1 when eureka2 starts

5.2.2 configure startup parameters

--spring.profiles.activeand--server.port

• Eureka1 startup parameters:

--spring.profiles.active=eureka1 --server.port=2001

• Eureka2 startup parameters:

--spring.profiles.active=eureka2 --server.port=2002

5.2.3 visit Eureka server to view the registration information

• http://eureka1:2001/

• http://eureka2:2002/

5.2.4 when registering Eureka client, register with two servers

Modify the following micro services

• sp02-itemservice
• sp03-userservice
• sp04-orderservice

eureka:
  client:
    service-url:
      defaultZone: http://eureka1:2001/eureka, http://eureka2:2002/eureka 

When one Eureka service goes down, it can still connect to another Eureka service