Docker部署.NET Core Api调用Selenium时出现地址分配失败问题

我开发了一个使用 Selenium Chrome Driver 的 .NET Core API，本地运行正常，但创建 Docker 镜像并运行时抛出 Cannot assign requested address (localhost:4444) 异常。

相关代码与配置 #

实例化 Chrome Driver 的代码 #

ChromeOptions options = new ChromeOptions();
options.AddArgument("no-sandbox");
options.AddArgument("headless");
driver = new RemoteWebDriver(new Uri("http://localhost:4444/wd/hub"), options);

Dockerfile #

FROM selenium/standalone-chrome:latest AS base
WORKDIR /app

# build and copy dotnet project
FROM mcr.microsoft.com/dotnet/aspnet:5.0
COPY bin/Release/net5.0/publish/ app/
WORKDIR /app
ENTRYPOINT ["dotnet", "Pand.dll"]

Docker Compose 配置 #

version: "3"
services:
  selenium-hub:
    image: selenium/hub:3.141.59-yttrium
    container_name: selenium-hub
    ports:
      - "4444:4444"
    expose: 
      - 4444
  chrome:
    image: selenium/standalone-chrome
    container_name: chrome
    deploy:
      replicas: 5
    ports:
      - "5900:5900"
    volumes:
      - /dev/shm:/dev/shm
    depends_on:
      - selenium-hub
    environment:
      - HUB_HOST=selenium-hub
      - HUB_PORT=4444
        #Api  Service
  api:
    build:
      context: .
      #Use the DockerFile in that Directory
      dockerfile: DockerFile
    environment: 
      - ASPNETCORE_ENVIRONMENT=Development

执行 docker run -p 8080:80 pand/backend 后的错误信息 #

crit: Microsoft.AspNetCore.Hosting.Diagnostics[6]
      Application startup exception
      OpenQA.Selenium.WebDriverException: An unknown exception was encountered sending an HTTP request to the remote WebDriver server for URL http://localhost:4444/wd/hub/session. The exception message was: Cannot assign requested address (localhost:4444)
       ---> System.Net.Http.HttpRequestException: Cannot assign requested address (localhost:4444)
       ---> System.Net.Sockets.SocketException (99): Cannot assign requested address
         at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.ThrowException(SocketError error, CancellationToken cancellationToken)
         at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token)
         at System.Net.Sockets.Socket.<ConnectAsync>g__WaitForConnectWithCancellation|283_0(AwaitableSocketAsyncEventArgs saea, ValueTask connectTask, CancellationToken cancellationToken)

问题原因与修复方案 #

核心问题 #

Docker 容器内的 localhost 指向容器自身的网络栈，而非宿主机或其他容器。API 容器尝试访问自身的 4444 端口，但该端口并未在容器内开放，导致连接失败。

修复步骤 #

1. 修改 RemoteWebDriver 连接地址
   将代码中的 http://localhost:4444/wd/hub 替换为 http://selenium-hub:4444/wd/hub。Docker Compose 会自动为服务创建 DNS 解析，通过服务名称 selenium-hub 可直接访问对应容器。

   修改后代码：

   ChromeOptions options = new ChromeOptions();
   options.AddArgument("no-sandbox");
   options.AddArgument("headless");
   driver = new RemoteWebDriver(new Uri("http://selenium-hub:4444/wd/hub"), options);
   

2. 通过 Docker Compose 启动集群
   不要单独用 docker run 启动 API 容器，执行 docker-compose up --build 启动所有服务。Docker 会自动创建共享网络，保证容器间的互通性。

3. 简化 Dockerfile（可选）
   Dockerfile 中 FROM selenium/standalone-chrome:latest AS base 未被后续阶段使用，可删除以简化镜像构建：

   FROM mcr.microsoft.com/dotnet/aspnet:5.0
   COPY bin/Release/net5.0/publish/ app/
   WORKDIR /app
   ENTRYPOINT ["dotnet", "Pand.dll"]
   

4. 添加启动重试逻辑（可选）
   depends_on 仅保证启动顺序，Selenium Hub 可能需要时间初始化。可在 API 启动时添加重试逻辑，避免因 Hub 未就绪导致的启动失败。

内容的提问来源于stack exchange，提问作者Sasan