Spring Boot微服务通过API网关访问端点出现503服务不可用错误

错误信息 #

{
    "timestamp": "2024-06-24T14:01:32.938+00:00",
    "path": "/departments",
    "status": 503,
    "error": "Service Unavailable",
    "requestId": "1a88ca39-1"
}

问题描述 #

所有服务已容器化，表面运行正常，但通过API网关访问端点返回503错误。Eureka注册中心仅注册了API网关，department-service、employee-service、project-service均未注册，推测核心问题是业务服务未正确从config-server获取配置，导致无法注册到Eureka，进而网关无法定位服务实例。

相关配置文件 #

服务注册中心（Eureka）配置 #

server:
  port: 8761

spring:
  application:
    name: service-registry

eureka:
  client:
    register-with-eureka: false
    fetch-registry: false
    serviceUrl:
      defaultZone: http://service-registry:8761/eureka/

API网关配置 #

server:
  port: 8060

eureka:
  client:
    serviceUrl:
      defaultZone: http://service-registry:8761/eureka/

spring:
  application:
    name: api-gateway
  cloud:
    gateway:
      routes:
        - id: employee-service
          uri: lb://employee-service
          predicates:
            - Path=/employees/**
        - id: department-service
          uri: lb://department-service
          predicates:
            - Path=/departments/**
        - id: project-service
          uri: lb://project-service
          predicates:
            - Path=/projects/**

Department服务本地配置 #

spring:
  application:
    name: department-service

  config:
    import: "optional:configserver:http://config-server:8088"

Employee和Project服务配置与Department一致，仅spring.application.name不同

Config Server配置 #

server:
  port: 8088

spring:
  application:
    name: config-server
  profiles:
    active: native
  cloud:
    config:
      server:
        native:
          search-locations: classpath:/config

Config Server中Department服务的配置 #

eureka:
  client:
    serviceUrl:
      defaultZone: http://service-registry:8761/eureka/

spring:
  application:
    name: department-service
  datasource:
    url: jdbc:jdbc:postgresql://postgres:5432/microservice_comp_data
    username: postgres
    password: password
    driver-class-name: org.postgresql.Driver
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true
    properties:
      hibernate:
        format_sql: true
    database: postgresql
    database-platform: org.hibernate.dialect.PostgreSQLDialect

server:
  error:
    include-message: always
  port: 8081


management:
  tracing:
    sampling:
      probability: 1.0

Employee和Project服务在Config Server中的配置与Department一致，仅spring.application.name和server.port不同

Docker Compose配置 #

version: '3.8'
services:
  config-server:
    build:
      context: ./config-server
    ports:
      - "8088:8088"

  service-registry:
    build:
      context: ./service-registry
    ports:
      - "8761:8761"
    depends_on:
      - config-server

  department-service:
    build:
      context: ./department-service
    ports:
      - "8081:8081"
    environment:
      SPRING_DATASOURCE_URL: jdbc:postgresql://postgres:5432/microservice_comp_data
      SPRING_DATASOURCE_USERNAME: postgres
      SPRING_DATASOURCE_PASSWORD: password
    depends_on:
      - service-registry
      - postgres

  employee-service:
    build:
      context: ./employee-service
    ports:
      - "8082:8082"
    environment:
      SPRING_DATASOURCE_URL: jdbc:postgresql://postgres:5432/microservice_comp_data
      SPRING_DATASOURCE_USERNAME: postgres
      SPRING_DATASOURCE_PASSWORD: password
    depends_on:
      - department-service

  project-service:
    build:
      context: ./project-service
    ports:
      - "8083:8083"
    environment:
      SPRING_DATASOURCE_URL: jdbc:postgresql://postgres:5432/microservice_comp_data
      SPRING_DATASOURCE_USERNAME: postgres
      SPRING_DATASOURCE_PASSWORD: password
    depends_on:
      - employee-service

  api-gateway:
    build:
      context: ./api-gateway
    ports:
      - "8060:8060"
    depends_on:
      - service-registry

  postgres:
    image: postgres:latest
    container_name: postgres-container
    environment:
      POSTGRES_DB: microservice_comp_data
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: password
    ports:
      - "5431:5432"

  zipkin:
    image: openzipkin/zipkin
    ports:
      - "9411:9411"

问题原因与修复步骤 #

1. 配置加载容错导致问题隐藏 #

业务服务配置中使用optional:configserver:，意味着config-server不可达时服务会忽略配置加载失败直接启动，不会抛出错误，但此时服务缺少Eureka注册配置，无法完成注册。

修复：移除optional:，强制服务从config-server获取配置，加载失败时直接报错，便于定位问题：

spring:
  config:
    import: "configserver:http://config-server:8088"

2. Docker依赖未考虑服务就绪状态 #

depends_on仅保证容器启动顺序，不保证服务内部初始化完成。可能出现service-registry容器启动了，但Eureka服务尚未就绪，此时业务服务启动时无法连接Eureka，注册失败。

修复：

• 为业务服务添加启动等待逻辑，比如使用wait-for-it脚本等待service-registry的8761端口就绪后再启动服务，需在服务Dockerfile中加入该脚本：

  department-service:
    # 其他配置不变
    command: ["./wait-for-it.sh", "service-registry:8761", "--", "java", "-jar", "app.jar"]
  

• 调整所有业务服务的depends_on，直接依赖config-server和service-registry，而非其他业务服务。

3. Config Server中数据库URL错误 #

Config Server里Department的数据库URL多写了一个jdbc:，导致数据库连接失败，服务启动异常，无法完成Eureka注册。

修复：修正数据库URL：

spring:
  datasource:
    url: jdbc:postgresql://postgres:5432/microservice_comp_data

4. 业务服务缺少Eureka客户端依赖 #

如果业务服务的依赖文件（pom.xml/build.gradle）中未引入Eureka Client依赖，即使配置了Eureka地址，也无法完成注册。

修复：添加Eureka Client依赖：

• Maven：

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

• Gradle：

implementation 'org.springframework.cloud:spring-cloud-starter-netflix-eureka-client'

5. 业务服务依赖链不合理 #

当前employee-service依赖department-service、project-service依赖employee-service，导致前序服务启动失败时后续服务也无法正常启动，且无必要。

修复：调整Docker Compose中业务服务的depends_on，改为直接依赖service-registry、postgres和config-server：

employee-service:
  # 其他配置不变
  depends_on:
    - service-registry
    - postgres
    - config-server

project-service:
  # 其他配置不变
  depends_on:
    - service-registry
    - postgres
    - config-server

内容的提问来源于stack exchange，提问作者Pangkey