Docker环境下Zipkin连接失败：请求localhost:9411被拒绝

Zipkin在本地运行正常，但部署到Docker容器后无法正常工作。所有微服务已成功注册到Eureka且通信正常，仅Zipkin出现问题，报错信息如下：

org.springframework.web.client.ResourceAccessException: I/O error on
POST request for "http://localhost:9411/api/v2/spans": Connect to
http://localhost:9411 [localhost/127.0.0.1] failed: Connection refused

我的docker-compose.yaml配置如下：

version: '3.8'

services:
  currency-exchange:
    image: samankt/springboot-udemy-currency-exchange:0.0.1-SNAPSHOT
    mem_limit: 512m
    ports:
      - '8000:8000'
    networks:
      - saman-network  
    environment:
      EUREKA.CLIENT.SERVICE-URL.DEFAULTZONE: http://naming-server:8761/eureka
      EUREKA.INSTANCE.PREFERIPADDRESS: true  
      SPRING.ZIPKIN.BASE-URL: http://zipkin-server:9411/
      RABBIT_URI: amqp://guest:guest@rabbitmq:5672
      SPRING_RABBITMQ_HOST: rabbitmq
      SPRING_ZIPKIN_SENDER_TYPE: rabbit
    depends_on:
      - naming-server
      - rabbitmq
      
  api-gateway:
    image: samankt/springboot-udemy-currency-api-gateway:0.0.1-snapshot
    mem_limit: 512m
    ports:
      - '8765:8765'
    networks:
      - saman-network  
    environment:
      EUREKA.CLIENT.SERVICE-URL.DEFAULTZONE: http://naming-server:8761/eureka
      EUREKA.INSTANCE.PREFERIPADDRESS: true  
      SPRING.ZIPKIN.BASE-URL: http://zipkin-server:9411/
      RABBIT_URI: amqp://guest:guest@rabbitmq:5672
      SPRING_RABBITMQ_HOST: rabbitmq
      SPRING_ZIPKIN_SENDER_TYPE: rabbit 
    depends_on:
      - naming-server
      - rabbitmq
      
  currency-converter:
    image: samankt/currency-conversion:0.0.1-SNAPSHOT
    mem_limit: 700m
    ports:
      - '8100:8100'
    networks:
      - saman-network  
    environment:
      EUREKA.CLIENT.SERVICE-URL.DEFAULTZONE: http://naming-server:8761/eureka
      EUREKA.INSTANCE.PREFERIPADDRESS: true  
      SPRING.ZIPKIN.BASE-URL: http://zipkin-server:9411/
      SPRING.ZIPKIN.DISCOVERYCLIENTENABLED: true 
      RABBIT_URI: amqp://guest:guest@rabbitmq:5672
      SPRING_RABBITMQ_HOST: rabbitmq
      SPRING_ZIPKIN_SENDER_TYPE: rabbit     
    depends_on:
      - naming-server
      - rabbitmq
      
  naming-server:
    image: samankt/naming-server:0.0.1-SNAPSHOT
    mem_limit: 512m
    ports:
      - '8761:8761'
    environment:
      SPRING.ZIPKIN.BASE-URL: http://zipkin-server:9411/    
    networks:
      - saman-network
      
  zipkin-server:
    image: openzipkin/zipkin:latest
    mem_limit: 400m
    ports:
      - '9411:9411'
    networks:
      - saman-network   
    environment:
      RABBIT_URI: amqp://guest:guest@rabbitmq:5672
    depends_on:
      - rabbitmq
    restart: always
      
      
  rabbitmq:
    image: rabbitmq:3.8.12-management
    ports:
      - '5672:5672'
      - '15672:15672'
    networks:
      - saman-network
    
networks: 
  saman-network:

问题根源 #

报错显示微服务尝试连接http://localhost:9411，但在Docker容器环境中，每个容器都是独立的网络命名空间，localhost指向容器自身而非宿主机的Zipkin服务。尽管你在docker-compose中配置了SPRING.ZIPKIN.BASE-URL: http://zipkin-server:9411/，但可能存在以下问题：

• 微服务镜像内部的配置文件硬编码了localhost:9411，覆盖了环境变量的配置
• currency-converter服务设置了SPRING.ZIPKIN.DISCOVERYCLIENTENABLED: true，可能导致服务发现逻辑优先于指定的base-url，引发连接错误

修复步骤 #

1. 清理硬编码配置：检查所有微服务的application.properties或application.yml，删除任何硬编码的spring.zipkin.base-url=http://localhost:9411配置，确保环境变量能正常覆盖。
2. 调整发现客户端配置：将currency-converter服务的SPRING.ZIPKIN.DISCOVERYCLIENTENABLED改为false，因为已经通过环境变量指定了明确的Zipkin地址，无需通过Eureka发现。
3. 重启服务集群：修改配置后，若配置是打包在镜像内，需重新构建镜像；然后执行docker-compose down && docker-compose up -d重启所有服务。
4. 验证网络连通性：进入任意微服务容器，执行curl http://zipkin-server:9411/health，确认能正常访问Zipkin的健康检查接口，验证网络连通性。

额外优化建议 #

• 添加服务依赖：在每个服务的depends_on中加入zipkin-server，确保启动顺序合理（注意：depends_on不保证服务就绪，仅保证启动顺序）。
• 配置Zipkin健康检查：为zipkin-server添加健康检查，确保服务完全就绪后再启动依赖服务，修改后的配置如下：

  zipkin-server:
    image: openzipkin/zipkin:latest
    mem_limit: 400m
    ports:
      - '9411:9411'
    networks:
      - saman-network   
    environment:
      RABBIT_URI: amqp://guest:guest@rabbitmq:5672
    depends_on:
      - rabbitmq
    restart: always
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost:9411/health"]
      interval: 10s
      timeout: 5s
      retries: 5
  

内容的提问来源于stack exchange，提问作者Saman KHATAEI