Microservice practice | Eureka registration center and cluster construction

Catalog

One 、SpringCloud System introduction

Two 、Eureka Server development

Create project parent project

Create a service terminal project

3、 ... and 、Eureka Server cluster construction

Four 、 establish Eureka client

5、 ... and 、 Project startup verification

6、 ... and 、Spring cloud Version introduction

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One 、SpringCloud System introduction

Microservice architecture has played an important role in cloud native architecture , and SpingCloud Undoubtedly, it is the integrator of microservice architecture , Cloud computing best business practices .

SpringCloud The system mainly includes the following components ：

• Service registration and discovery ： Such as Eureka、Consul、Nacos、zookeeper etc. ;
• Service configuration management ： Such as SpringCloud config、zookeeper、Nacos、Apollo etc. ;
• The service call ： Such as Feign、Ribbon、RestTemplate etc. ;
• Service failure ： Such as Hystrix、Sentinel etc. ;
• The service gateway ： Such as SpringCloud Gateway、Zuul etc. ;
• Client load balancing ： Such as Ribbon etc. ;
• Service link tracking ： Such as Sleuth etc. ;
• Service message bus ： Such as SpringCloud Bus etc. ;
• Distributed message ： Such as SpringCloud Stream+RocketMQ etc. ;
• Distributed transactions ： Such as Seata etc. .

Eureka yes Netflix Developed service discovery framework ,SpringCloud Integrate it into your own subproject spring-cloud-netflix in , Realization SpringCloud Service discovery capabilities for .Eureka contain Eureka Server and Eureka Client Two components .

• Eureka Server Provide service registration service , After each node is started , Will be in Eureka Server Register in , such Eureka Server The service registry in will store information about all available service nodes .
• Eureka Client It's a java client , Used with Eureka Server Interaction , The client also has a built-in 、 Use polling (round-robin) Load balancer of load algorithm . After the app starts , Will Eureka Server Send a heartbeat , The default period is 30 second , If Eureka Server The heartbeat of a node is not received in multiple heartbeat cycles ,Eureka Server This service node will be removed from the service registry ( Default 90 second ).

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Two 、Eureka Server development

Create project parent project

1. newly build maven Parent project parent, For unified management of dependencies .
2. introduce pom rely on , the SpringCloud The version is Hoxton.SR3

<modelVersion>4.0.0</modelVersion>
    <groupId>com.cxy965</groupId>
    <artifactId>parent</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <description>A maven project to study maven.</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.2.RELEASE</version>
        <relativePath/>
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.SR3</spring-cloud.version>
    </properties>

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

Create a service terminal project

• Create the first server project of the registry registry
• introduce eureka-server Dependence

    <groupId>com.cxy965</groupId>
    <artifactId>registry</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>com.cxy965</groupId>
        <artifactId>parent</artifactId>
        <version>1.0-SNAPSHOT</version>
        <relativePath>../parent/pom.xml</relativePath>
    </parent>

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

• Write the startup class , increase @EnableEurekaServer annotation , Expressed as server side

package com.cxy965.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

/**
 * @Author: official account : The programmer 965
 * @create 2022-06-06
 **/
@EnableEurekaServer
@SpringBootApplication
public class RegistryApplication {
    public static void main(String[] args) {
        SpringApplication.run(RegistryApplication.class, args);
    }
}

• newly build application.yml The configuration file , Define port and other information

server:
  port: 8001
spring:
  application:
    name: registry
eureka:
  instance:
    hostname: 0.0.0.0
    lease-renewal-interval-in-seconds: 10 # Service registration involves heartbeat connection , Default is every 30s
    lease-expiration-duration-in-seconds: 30 # The default time when the service is removed is 90s
  client:
    healthcheck:
      enabled: true # Turn on the heartbeat 
    register-with-eureka: false
    fetch-registry: false
    serviceUrl:
      defaultZone:  http://${eureka.instance.hostname}:${server.port}/eureka/
    registry-fetch-interval-seconds: 30 #eureka client How often do I get the service registration information , The default is 30 second 

So the first one Eureka The development of the server is completed , Next, we create a cluster .

3、 ... and 、Eureka Server cluster construction

If you want to build a server cluster , Need to open Eureka Cluster configuration , When each server is started Eureka Server Will send the registration information to other Eureka Server To synchronize , Therefore, to build a highly available cluster architecture, you only need to Eureke Server The configuration points to other available serviceUrl that will do .

• Copy above Eureka Single server project , Create the first service of the cluster eurekaserver1;
• modify application.yml The configuration file ;

on top Eureka Based on a single server project , Modify... In the configuration file  register-with-eureka、fetch-registry as well as serviceUrl.defaultZone Parameters , as follows ：

server:
  port: 8001
spring:
  application:
    name: registry
eureka:
  instance:
    hostname: 0.0.0.0
    lease-renewal-interval-in-seconds: 10 # Service registration involves heartbeat connection , Default is every 30s
    lease-expiration-duration-in-seconds: 30 # The default time when the service is removed is 90s
  client:
    healthcheck:
      enabled: true # Turn on the heartbeat 
    register-with-eureka: true
    fetch-registry: true
    serviceUrl:
      defaultZone:  http://localhost:8002/eureka/,http://localhost:8003/eureka/
    registry-fetch-interval-seconds: 30 #eureka client How often do I get the service registration information , The default is 30 second 

• alike , Copy again eurekaserver1 by eurekaserver2,eurekaserver3 Two projects ;
• take eurekaserver2、eurekaserver3 The ports of are changed to 8002、8003;
• take eurekaserver2、eurekaserver3 The registered address of is changed into 8001/8003 and 8001/8002;

To start, respectively, eurekaserver1、eurekaserver2、eurekaserver3 Three items are enough .

Be careful , Because it is a local test project , All three projects are deployed locally localhost, As a highly available cluster environment , To prevent other items in the cluster from being available after the server crashes , It needs to be deployed on different servers , Deployed on different servers , The port can be changed to the same .

Four 、 establish Eureka client

• Create the first client project client
• The difference with the server is , The client needs to introduce eureka-client Dependence

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

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

• Write the startup class , Note that @EnableEurekaClient annotation , Indicates that this is a client

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

/**
 * @Author: official account ： The programmer 965
 * @create 2022-06-06
 **/
@EnableEurekaClient
@SpringBootApplication
public class AppApplication {
    public static void main(String[] args) {
        SpringApplication.run(AppApplication.class, args);
    }
}

• establish application.yml The configuration file , Register to the server

server:
  port: 8002
spring:
  application:
    name: app

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8001/eureka/

5、 ... and 、 Project startup verification

Start server and client respectively , Open the browser and enter http://localhost:8001/; Display the successful registration of the client ：

summary ：Eureka Server Data synchronization is completed by means of replication ,Eureka It also provides client caching mechanism , Even if all Eureka Server All hang up , The client can still use the information in the cache to consume other services API. Sum up ,Eureka Through a heartbeat check 、 Client caching and other mechanisms , Ensure the high availability of the system 、 Flexibility and scalability .

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6、 ... and 、Spring cloud Version introduction

stay 2020 year 4 Before month , To avoid confusion with subprojects ,SpringCloud Version is based on Name of London Underground Station name , And publish in alphabetical order ： such as Angle、Brixton、Camden、Edgware、Finchley、GreenWich、Hoxton etc. . The meaning of the letters in the version number ：

• SNAPSHOT： Snapshot version , unstable 、 Version in development ; 
• M： MileStone,M1 It means the first one 1 Milestone version ;
• RC：Release Candidate, Candidate version , General Label PRE Show preview , Almost no new features will be added , Repair only bug;
• RELEASE： Official version , If published Edgware SR1 Before , It will be released first Edgware RELEASE;
• SR： Service Release, The release point of a single project accumulates to a critical value , Or there is a key bug It will be released when it needs to be provided to everyone SR edition , Such as SR1 Version may solve a number of key bug, Generally, mark at the same time GA;
• GA：General Availability, Officially released stable version （ Some software may be identified as Stable Version or Production edition , Its meaning and GA identical ）;

  Maybe the release is too fast , The subway station name is not enough ,2020 year 4 The version released after the month is changed to Calendar version （Calendar Versioning） Naming method , The format is “YYYY.MINOR.MICRO-SNAPSHOT/M1/RC2”.

• YYYY： representative 4 Bit year ;
• MINOR： Means a year with 0 The number that starts to increase ;
• MICRO： Suffix indicating version number , .0 Be similar to .RELEASE equally ,.2 Be similar to .SR2.
• The snapshot and pre release version numbers are also changed from the previous . Change it to -, Such as ：2020.0.0-SNAPSHOT/M1/RC2;

The possible order of release is as follows ：

SNAPSHOT-->M-->RC-->RELEASE-->SR--GA

  How to choose so many versions ？

Latest and marked GA Version of , Best choice SR The later version with larger numbers .