Docker容器在CentOS VPS服务器创建失败，Selenium Hub连接被拒

本地环境下，通过docker-compose集成Selenium、Chrome Driver、MySQL搭建的网站后端可正常运行，但部署到CentOS系统的VPS服务器时，出现连接selenium-hub:4444被拒绝的错误，报错信息如下：

web_1           | crit: Microsoft.AspNetCore.Hosting.Diagnostics[6]
web_1           |       Application startup exception
web_1           |       OpenQA.Selenium.WebDriverException: An unknown exception was encountered sending an HTTP request to the remote WebDriver server for URL http://selenium-hub:4444/wd/hub/session. The exception message was: Connection refused (selenium-hub:4444)
web_1           |        ---> System.Net.Http.HttpRequestException: Connection refused (selenium-hub:4444)
web_1           |        ---> System.Net.Sockets.SocketException (111): Connection refused
web_1           |          at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.ThrowException(SocketError error, CancellationToken cancellationToken)
web_1           |          at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token)
web_1           |          at System.Net.Sockets.Socket.<ConnectAsync>g__WaitForConnectWithCancellation|283_0(AwaitableSocketAsyncEventArgs saea, ValueTask connectTask, CancellationToken cancellationToken)

我的docker-compose配置文件：

version: "3"

volumes:
  datafiles:

services:

  database:
    image: mysql:8.0.28
    depends_on:
      - selenium-hub
    ports:
      - "3307:3306"
    volumes:
      - datafiles:/var/lib/mysql
      - "~/sql-scripts/setup.sql:/docker-entrypoint-initdb.d/1.sql"
    restart: always
    environment: 
      MYSQL_ROOT_PASSWORD: *****
      MYSQL_USER: sa
      MYSQL_PASSWORD: ******
      MYSQL_DATABASE: Pan

  chrome:
    image: selenium/node-chrome:4.3.0-20220706
    shm_size: 2gb
    depends_on:
      - selenium-hub
    environment:
      - SE_EVENT_BUS_HOST=selenium-hub
      - SE_EVENT_BUS_PUBLISH_PORT=4442
      - SE_EVENT_BUS_SUBSCRIBE_PORT=4443

  selenium-hub:
    image: selenium/hub:4.3.0-20220706
    container_name: selenium-hub
    ports:
      - "4442:4442"
      - "4443:4443"
      - "4444:4444"  
  web:
     build: .
     ports: 
       - "8080:80"
     depends_on:
       - database
       - selenium-hub
       - chrome
     restart: always

创建Driver的C#代码片段：

ChromeOptions options = new ChromeOptions();
options.AddArgument("no-sandbox");
options.AddArgument("headless");

driver = new RemoteWebDriver(new Uri("http://selenium-hub:4444/wd/hub"), options);

解决方案 #

1. 解决服务启动顺序与就绪问题 #

depends_on仅保证容器启动顺序，不确保服务完全就绪。当web服务启动时，selenium-hub可能还在初始化，导致连接拒绝。

修改docker-compose配置，给selenium-hub添加健康检查，并让web服务等待selenium-hub就绪后再启动：

selenium-hub:
  image: selenium/hub:4.3.0-20220706
  container_name: selenium-hub
  ports:
    - "4442:4442"
    - "4443:4443"
    - "4444:4444"
  healthcheck:
    test: ["CMD", "curl", "-f", "http://localhost:4444/wd/hub/status"]
    interval: 10s
    timeout: 5s
    retries: 5

web:
   build: .
   ports: 
     - "8080:80"
   depends_on:
     database:
       condition: service_started
     selenium-hub:
       condition: service_healthy
     chrome:
       condition: service_started
   restart: always

2. 检查CentOS的SELinux与防火墙设置 #

CentOS默认开启的SELinux可能会拦截容器间的通信，执行以下命令临时关闭测试（如需永久关闭需修改配置文件）：

setenforce 0

如果问题解决，可通过以下命令允许Docker容器间通信：

setsebool -P docker_connect_any 1

同时检查防火墙是否拦截了容器端口，可临时关闭防火墙测试：

systemctl stop firewalld

确认没问题后，可按需开放端口或配置防火墙规则允许Docker网络通信。

3. 验证Selenium Hub与Chrome节点状态 #

查看selenium-hub日志，确认服务正常启动且Chrome节点已注册：

docker logs selenium-hub

若日志中无节点注册信息，检查chrome服务的环境变量是否正确，或尝试重启chrome容器：

docker-compose restart chrome

4. 优化ChromeOptions参数 #

在代码中添加--disable-dev-shm-usage参数，避免CentOS系统中共享内存不足的问题：

ChromeOptions options = new ChromeOptions();
options.AddArgument("no-sandbox");
options.AddArgument("headless");
options.AddArgument("--disable-dev-shm-usage"); // 添加此参数

driver = new RemoteWebDriver(new Uri("http://selenium-hub:4444/wd/hub"), options);

内容的提问来源于stack exchange，提问作者Sasan