Spring Boot忽略环境变量：无法连接Eureka容器问题排查

环境配置 #

Docker Compose 文件 #

version: '2.1'

services:
  app:
    build:
      context: .
      dockerfile: Dockerfile
    ports:
      - "8100:8100"
    depends_on:
      eureka:
        condition: service_healthy
    environment:
      EUREKA_URL: http://eureka:8761/eureka

  eureka:
    image: nadchel/eureka-server:1.0
    ports:
      - "8761:8761"
    healthcheck:
      test: ["CMD-SHELL", "curl -f http://eureka:8761"]
      interval: 10s
      timeout: 10s
      retries: 10

应用POM依赖配置 #

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.2.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>token-service</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>token-service</name>
    <description>token-service</description>
    <properties>
        <java.version>17</java.version>
        <spring-cloud.version>2023.0.0</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

<!-- ... -->

    <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>

应用配置文件 #

spring:
  application:
    name: token-service

eureka:
  client:
    availability-zones:
      defaultZone: ${EUREKA_URL:http://localhost:8761/eureka}

问题现象 #

应用启动后无法连接Eureka容器，日志报错如下：

token-service-app-1     | 2024-02-21T23:41:51.863Z  WARN 1 --- [token-service] [nfoReplicator-0]
c.n.d.s.t.d.RetryableEurekaHttpClient    : Request execution failed with message: 
I/O error on POST request for "http://localhost:8761/eureka/apps/TOKEN-SERVICE": 
Connect to http://localhost:8761 [localhost/127.0.0.1] failed: Connection refused 

明明已经通过环境变量传入http://eureka:8761/eureka，且配置文件中引用了该变量，但应用仍尝试访问localhost。

已排查情况 #

• 环境变量格式验证：Docker Compose中的environment格式符合官方规范，示例参考：

  environment:
    RACK_ENV: development
    SHOW: 'true'
    SESSION_SECRET:
  

• 容器内环境变量确认：进入app容器执行env命令，已确认EUREKA_URL=http://eureka:8761/eureka存在：

  docker exec token-service-app-1 /bin/sh -c "env"                                                                              
  POSTGRES_USERNAME=postgres                                                                                                                                                  
  HOSTNAME=2e671f5bd313                                                                                                                                                       
  SHLVL=1                                                                                                                                                                     
  HOME=/root                                                                                                                                                                  
  EUREKA_URL=http://eureka:8761/eureka                                                                                                                                         
  POSTGRES_PASSWORD=postgres                                                                                                                                                  
  PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/lib/jvm/default-jvm/bin                                                                              
  LANG=C.UTF-8                                                                                                                                                                
  POSTGRES_URL=jdbc:postgresql://db:5432/postgres                                                                                                                             
  JAVA_HOME=/usr/lib/jvm/default-jvm                                                                                                                                           
  PWD=/app   
  

• 版本差异排查：对比了Eureka服务的版本，其使用Spring Boot 3.1.3和Spring Cloud 2022.0.4，与当前应用的版本存在差异，但其他同版本差异的服务可正常运行：

  <!-- Eureka的pom：Boot和Cloud版本稍旧 -->
  
      <parent>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-parent</artifactId>
          <version>3.1.3</version>
          <relativePath/> <!-- lookup parent from repository -->
      </parent>
      <groupId>com.example</groupId>
      <artifactId>EurekaServer</artifactId>
      <version>0.0.1-SNAPSHOT</version>
      <name>EurekaServer</name>
      <description>EurekaServer</description>
      <properties>
          <java.version>17</java.version>
          <spring-cloud.version>2022.0.4</spring-cloud.version>
  

内容的提问来源于stack exchange，提问作者Sergey Zolotarev