Eureka Server + API Gateway + DiscoveryClient 설정

1. 기존서비스 DiscoveryClient 변환

• pom.xml

eureka client dependency 추가

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

dependencyManagement 설정

<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>

spring-boot version = 2.5.5
spring-cloud version = 2020.0.4

• Application.java

@EnableDiscoveryClient
public class TaxApplication {
	...
}

@EnableDiscoveryClient 어노테이션 추가

• application.yml

server:
    port: 0
            
eureka:
    client:
        register-with-eureka: true
        fetch-registry: true
        service-url:
            defaultZone: http://localhost:8761/eureka
    instance:
        instance-id: ${spring.application.name}:${spring.application.instance_id:${random.value}}
        
spring:
    application:
        name: etaxbill-service

server.port = 0 랜덤포트 설정
instance-id를 설정하여 client 인스턴스 구분 표시

2. API Gateway 설정

server:
    port: 8443

eureka:
    client:
        register-with-eureka: true
        fetch-registry: true
        service-url:
            defaultZone: http://localhost:8761/eureka

spring:
    application:
        name: apigateway-service
    cloud:
        gateway:
            default-filters:
                -   name: GlobalFilter
                    args:
                        baseMessage: Spring Cloud Gateway Global filter
                        preLogger: true
                        postLogger: true
            routes:
                -   id: tax-invoice
                    # uri: http://tax.blueport.co.kr:8443/
                    uri: lb://etaxbill-service
                    predicates:
                        - Path=/v1/**
                    filters:
                        # - AddRequestHeader=headerName, headerValue
                        # - AddResponseHeader=headerName2, headerValue2
                        - CustomFilter

uri주소를 'lb://서비스명'으로 찾음. (spring.application.name)
서비스명은 자동 uppercase됨.

API 요청 -> API Gateway -> Eureka Server:Service Discovery,Registration(위치정보 및 라우팅, 로드밸런싱) -> API Gateway -> Discovery Client(해당서비스 수행)