Eureka Actual Warfare-3 [Supporting Remote Region]

Engineering public pom dependence

<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>Finchley.RELEASE</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>
        </dependencies>
</dependencyManagement>

1. Ereka server project

1.1. Ereka server project pom dependence:

<!--Plus the public dependence on the header of the article-->

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

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

1.2. Project Startup Class:

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

@SpringBootApplication
@EnableEurekaServer
public class EurkeaServerApplication {

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

1.3. Four instances of eureka server are configured here. The paths are: eureka-server src main resources divided into four zone s, which belong to region-east and region-west.

The configuration files belonging to region-east are: application-zone 1.yml, application-zone 2.yml

application-zone1.yml:

server:
  port: 8761
spring:
  application:
    name: eureka-server
eureka:
  server:
    waitTimeInMsWhenSyncEmpty: 0
    enableSelfPreservation: false
    remoteRegionUrlsWithName:
      region-west: http://localhost:8763/eureka/
  client:
    register-with-eureka: true
    fetch-registry: true
    region: region-east
    service-url:
      zone1: http://localhost:8761/eureka/
      zone2: http://localhost:8762/eureka/
    availability-zones:
      region-east: zone1,zone2
  instance:
    hostname: localhost
    metadataMap.zone: zone1

application-zone2.yml:

server:
  port: 8762
spring:
  application:
    name: eureka-server
eureka:
  server:
    waitTimeInMsWhenSyncEmpty: 0
    enableSelfPreservation: false
    remoteRegionUrlsWithName:
      region-west: http://localhost:8763/eureka/
  client:
    register-with-eureka: true
    fetch-registry: true
    region: region-east
    service-url:
      zone1: http://localhost:8761/eureka/
      zone2: http://localhost:8762/eureka/
    availability-zones:
      region-east: zone1,zone2
  instance:
    hostname: localhost
    metadataMap.zone: zone2

The configuration files belonging to region-west are: application-zone 3-region-west.yml, application-zone 4-region-west.yml.

application-zone3-region-west.yml

server:
  port: 8763
spring:
  application:
    name: eureka-server
eureka:
  server:
    waitTimeInMsWhenSyncEmpty: 0
    enableSelfPreservation: false
    remoteRegionUrlsWithName:
      region-east: http://localhost:8761/eureka/
  client:
    register-with-eureka: true
    fetch-registry: true
    region: region-west
    service-url:
      zone3: http://localhost:8763/eureka/
      zone4: http://localhost:8764/eureka/
    availability-zones:
      region-west: zone3,zone4
  instance:
    hostname: localhost
    metadataMap.zone: zone3

application-zone4-region-west.yml

server:
  port: 8764
spring:
  application:
    name: eureka-server
eureka:
  server:
    waitTimeInMsWhenSyncEmpty: 0
    enableSelfPreservation: false
    remoteRegionUrlsWithName:
      region-east: http://localhost:8761/eureka/
  client:
    register-with-eureka: true
    fetch-registry: true
    region: region-west
    service-url:
      zone3: http://localhost:8763/eureka/
      zone4: http://localhost:8764/eureka/
    availability-zones:
      region-west: zone3,zone4
  instance:
    hostname: localhost
    metadataMap.zone: zone4

Because in the framework, the default value of Eureka Server ConfigBean's remoteRegionAppWhitelist is null, and the getRemoteRegionAppWhitelist(String regionName) method is called directly, if it is not handled in the project, the direct null pointer exception will occur.

//Frame source
package org.springframework.cloud.netflix.eureka.server;

import ......

@ConfigurationProperties("eureka.server")
public class EurekaServerConfigBean implements EurekaServerConfig {
    public static final String PREFIX = "eureka.server";
    private static final int MINUTES = 60000;
    @Autowired(
        required = false
    )
    PropertyResolver propertyResolver;
    private String aWSAccessId;
    //.....private String[] remoteRegionUrls;
    private Map<String, Set<String>> remoteRegionAppWhitelist;
　　//......
}

so, in the eureka server project, add the following configuration:

import com.netflix.discovery.EurekaClientConfig;
import com.netflix.eureka.EurekaServerConfig;
import org.springframework.boot.autoconfigure.AutoConfigureBefore;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration;
import org.springframework.cloud.netflix.eureka.server.EurekaServerConfigBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.HashMap;

/**
 * Configuration class
 */
@Configuration
@AutoConfigureBefore(EurekaServerAutoConfiguration.class)//Current configuration class EurekaServerAutoConfiguration Follow-up Loading after Loading
public class RegionConfig {

    @Bean
    @ConditionalOnMissingBean
    public EurekaServerConfig eurekaServerConfig(EurekaClientConfig clientConfig) {
        EurekaServerConfigBean server = new EurekaServerConfigBean();
        if (clientConfig.shouldRegisterWithEureka()) {
            server.setRegistrySyncRetries(5);
        }
        server.setRemoteRegionAppWhitelist(new HashMap<>());
        return server;
    }
}

1.4. Start the instance and execute the command:

mvn spring-boot:run -Dspring.profiles.active=zone1
mvn spring-boot:run -Dspring.profiles.active=zone2
mvn spring-boot:run -Dspring.profiles.active=zone3-region-west
mvn spring-boot:run -Dspring.profiles.active=zone4-region-west

2. Eureka Client Project

2.1. Ereka Client project pom dependence:

<!--Plus article header public dependency-->

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

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

2.2. Ereka Client Project Startup Class:

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient
public class EurekaClientApplication {

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

2.3. Ereka Client Engineering Configuration File

There are four client instances, which are also divided into four zone s, belonging to region-east and region-west.

The configuration files belonging to region-east are: application-zone 1.yml, application-zone 2.yml

application-zone1.yml:

server:
  port: 8071
spring:
  application.name: demo-client
eureka:
  client:
    prefer-same-zone-eureka: true
    region: region-east
    service-url:
      zone1: http://localhost:8761/eureka/
      zone2: http://localhost:8762/eureka/
    availability-zones:
      region-east: zone1,zone2
  instance:
    metadataMap.zone: zone1

application-zone2.yml

server:
  port: 8072
spring:
  application.name: demo-client
eureka:
  client:
    prefer-same-zone-eureka: true
    region: region-east
    service-url:
      zone1: http://localhost:8761/eureka/
      zone2: http://localhost:8762/eureka/
    availability-zones:
      region-east: zone1,zone2
  instance:
    metadataMap.zone: zone2

The configuration files belonging to region-west are: application-zone 3.yml, application-zone 4.yml

application-zone3.yml:

server:
  port: 8073
spring:
  application.name: demo-client
eureka:
  client:
    prefer-same-zone-eureka: true
    region: region-west
    service-url:
      zone3: http://localhost:8763/eureka/
      zone4: http://localhost:8764/eureka/
    availability-zones:
      region-west: zone3,zone4
  instance:
    metadataMap.zone: zone3

application-zone4.yml:

server:
  port: 8074
spring:
  application.name: demo-client
eureka:
  client:
    prefer-same-zone-eureka: true
    region: region-west
    service-url:
      zone3: http://localhost:8763/eureka/
      zone4: http://localhost:8764/eureka/
    availability-zones:
      region-west: zone3,zone4
  instance:
    metadataMap.zone: zone4

application.yml:

management:
  endpoints:
    web:
      exposure:
        include: '*'

2.4. Start the eureka client project and execute the order:

mvn spring-boot:run -Dspring.profiles.active=zone1
mvn spring-boot:run -Dspring.profiles.active=zone2
mvn spring-boot:run -Dspring.profiles.active=zone3
mvn spring-boot:run -Dspring.profiles.active=zone4

3. Zuul Gateway Project

3.1. zuul gateway project pom dependence:

<!--Plus the public dependence on the header of the article--> 

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

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

3.2. zuul gateway project startup class:

package cn.springcloud.book;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.zuul.EnableZuulProxy;

@SpringBootApplication
@EnableZuulProxy
@EnableDiscoveryClient
public class ZuulGatewayApplication {

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

3.3. zuul gateway project configuration file. Two gateway instances are used to demonstrate the application instance function of fallback to remote region. One belongs to region-east and the other belongs to region-west.

application.yml:

spring:
  application:
    name: zuul-gateway
management:
  endpoints:
    web:
      exposure:
        include: '*'

application-zone1.yml:

server:
  port: 10001
eureka:
  instance:
    metadataMap.zone: zone1
  client:
    register-with-eureka: true
    fetch-registry: true
    region: region-east
    service-url:
      zone1: http://localhost:8761/eureka/
      zone2: http://localhost:8762/eureka/
    availability-zones:
      region-east: zone1,zone2

application-zone3-region-west.yml:

server:
  port: 10002
eureka:
  instance:
    metadataMap.zone: zone3
  client:
    register-with-eureka: true
    fetch-registry: true
    region: region-west
    service-url:
      zone3: http://localhost:8763/eureka/
      zone4: http://localhost:8764/eureka/
    availability-zones:
      region-west: zone3,zone4

3.4. Start the gateway project and execute the command:

mvn spring-boot:run -Dspring.profiles.active=zone1
mvn spring-boot:run -Dspring.profiles.active=zone3-region-west

Visit: localhost:10001/demo-client/actuator/env. The results are as follows:

Visit: localhost:10002/demo-client/actuator/env, the results are as follows:

You can see the Zone Affinity feature( As mentioned in the last article The gateway of zone 1 accesses demo-client of zone 1, and the gateway of zone 3 accesses demo-client of zone 3.

Next, close the zone 1 instance of eureka-client and continue visiting localhost:10001/demo-client/actuator/env. You can see that after several errors, automatic fallback is implemented on the zone 4 instance of remote-region, which achieves the effect similar to remote multi-activity automatic transfer request.

Keywords: Java Spring Maven

Added by tamayo on Sun, 06 Oct 2019 11:10:21 +0300

Programming VIP

Eureka Actual Warfare-3 [Supporting Remote Region]

Engineering public pom dependence

1. Ereka server project

2. Eureka Client Project

3. Zuul Gateway Project

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