如何在.NET Docker容器中以有头模式运行Playwright？

我在Docker容器中使用Playwright运行有头模式的Firefox时失败，但无头模式可以正常工作。该镜像基于Ubuntu 22，以下是我的相关配置、代码及错误信息：

Dockerfile #

FROM mcr.microsoft.com/dotnet/aspnet:6.0 AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443

RUN apt-get update && apt-get install -y --no-install-recommends \
    xvfb\
    fonts-liberation\
    libasound2\
    libatk-bridge2.0-0\
    libatk1.0-0\
    libatspi2.0-0\
    libcairo2\
    libcups2\
    libdbus-glib-1-2\
    libdbus-1-3\
    libdrm2\
    libgbm1\
    libglib2.0-0\
    libgtk-3-0\
    libnspr4\
    libnss3\
    libpango-1.0-0\
    libx11-6\
    libxcb1\
    libxcomposite1\
    libxdamage1\
    libxext6\
    libxfixes3\
    libxrandr2\
    libxtst6\
    tzdata 


FROM mcr.microsoft.com/dotnet/sdk:6.0 AS build
WORKDIR /src
COPY ["src/Project.csproj", "src/"]
RUN dotnet restore "src/Project.csproj"
COPY . .
WORKDIR "/src/src"
RUN dotnet build "Project.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "Project.csproj" -c Release -o /app/publish /p:UseAppHost=false

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .

##ENV DISPLAY=:99

# Start Xvfb, set DISPLAY variable, and run the application
##ENTRYPOINT ["/usr/bin/xvfb-run -a $@", "dotnet", "Project.dll"]
#ENTRYPOINT ["/bin/sh", "-c", "/usr/bin/xvfb-run -a $@", ""]

##CMD ["xvfb-run", "dotnet", "Project.dll"]
##CMD Xvfb :99 -ac & export DISPLAY=:99 && dotnet Project.dll
ENTRYPOINT ["dotnet", "Project.dll"]

注释部分是我多次尝试但未成功的启动命令。

C#代码 #

using (var pw = await Playwright.CreateAsync())
{
    var proxyHandler = new ProxyHandler();

    await using var browser = await pw.Firefox.LaunchAsync(new BrowserTypeLaunchOptions()
    {
        Headless = false
    });

    var context = browser.NewContextAsync(new BrowserNewContextOptions() 
    { 
        IgnoreHTTPSErrors = true
    });

    var page = await browser.NewPageAsync();

    await page.GotoAsync("http://page");
}

错误日志 #

2023-09-21 21:33:31       An unhandled exception has occurred while executing the request.
2023-09-21 21:33:31       Microsoft.Playwright.PlaywrightException: 
2023-09-21 21:33:31       ╔════════════════════════════════════════════════════════════════════════════════════════════════╗
2023-09-21 21:33:31       ║ Looks like you launched a headed browser without having a XServer running.                     ║
2023-09-21 21:33:31       ║ Set either 'headless: true' or use 'xvfb-run <your-playwright-app>' before running Playwright. ║
2023-09-21 21:33:31       ║                                                                                                ║
2023-09-21 21:33:31       ║ <3 Playwright Team                                                                             ║
2023-09-21 21:33:31       ╚════════════════════════════════════════════════════════════════════════════════════════════════╝
2023-09-21 21:33:31       =========================== logs ===========================
2023-09-21 21:33:31       <launching> /ms-playwright/firefox-1422/firefox/firefox -no-remote -wait-for-browser -foreground -profile /tmp/playwright_firefoxdev_profile-PVqbMc -juggler-pipe -silent
2023-09-21 21:33:31       <launched> pid=954
2023-09-21 21:33:31       [pid=954][err] Error: no DISPLAY environment variable specified
2023-09-21 21:33:31       [pid=954] <process did exit: exitCode=1, signal=null>

解决方案 #

问题核心是有头浏览器需要X服务器运行，而你的启动命令没有正确启动Xvfb并传递DISPLAY环境变量。修改Dockerfile的final阶段即可解决：

修改后的Dockerfile final阶段 #

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .

# 设置DISPLAY环境变量
ENV DISPLAY=:99

# 通过shell启动xvfb-run和应用，确保X服务器正常运行
ENTRYPOINT ["/bin/sh", "-c", "/usr/bin/xvfb-run -a dotnet Project.dll"]

关键说明 #

1. xvfb-run -a：自动启动一个Xvfb虚拟X服务器，-a参数会自动选择可用的显示编号，避免固定:99可能带来的冲突。
2. /bin/sh -c：由于Docker的ENTRYPOINT exec格式（方括号）不支持shell语法，必须通过shell来执行xvfb-run与dotnet的组合命令，确保环境变量正确传递。

另外，你的C#代码中有个小问题：browser.NewContextAsync没有使用await，建议修复为await browser.NewContextAsync(...)，避免潜在的异步问题。

内容的提问来源于stack exchange，提问作者Andy Schmitt