即使在.net核心控制台应用程序中使用Console.ReadLine(),docker容器也会立即退出

Question

我试图在docker容器中运行.net核心1.0.0控制台应用程序.
当我dotnet run从我的机器上的Demo文件夹中运行命令时,它工作正常; 但是当使用时docker run -d --name demo Demo,容器会立即退出.

我试图docker logs demo检查日志,它只显示Console.WriteLine中的文本:

演示应用运行...

没有别的.

我已经在https://github.com/learningdockerandnetcore/Demo上传了该项目

该项目包含Programs.cs,Dockerfile用于创建Demo图像和project.json文件.

Answer 1

如果将应用程序切换到目标.net core 2.0,则可以使用Microsoft.Extensions.Hosting pacakge通过使用HostBuilder API来启动/停止应用程序来托管.net核心控制台应用程序.其ConsoleLifetime类将处理常规应用程序启动/停止方法.

为了运行您的应用程序,您应该实现自己的IHostedService接口或从BackgroundService类继承,然后将其添加到主机上下文中ConfigureServices.

namespace Microsoft.Extensions.Hosting
{
    //
    // Summary:
    //     Defines methods for objects that are managed by the host.
    public interface IHostedService
    {
        // Summary:
        // Triggered when the application host is ready to start the service.
        Task StartAsync(CancellationToken cancellationToken);

        // Summary:
        // Triggered when the application host is performing a graceful shutdown.
        Task StopAsync(CancellationToken cancellationToken);
    }
}

这是一个示例托管服务:

public class TimedHostedService : IHostedService, IDisposable
{
    private readonly ILogger _logger;
    private Timer _timer;

    public TimedHostedService(ILogger<TimedHostedService> logger)
    {
        _logger = logger;
    }

    public Task StartAsync(CancellationToken cancellationToken)
    {
        _logger.LogInformation("Timed Background Service is starting.");

        _timer = new Timer(DoWork, null, TimeSpan.Zero, 
            TimeSpan.FromSeconds(5));

        return Task.CompletedTask;
    }

    private void DoWork(object state)
    {
        _logger.LogInformation("Timed Background Service is working.");
    }

    public Task StopAsync(CancellationToken cancellationToken)
    {
        _logger.LogInformation("Timed Background Service is stopping.");

        _timer?.Change(Timeout.Infinite, 0);

        return Task.CompletedTask;
    }

    public void Dispose()
    {
        _timer?.Dispose();
    }
}

然后创建HostBuilder并添加服务和其他组件(日志记录,配置).

public class Program
{
    public static async Task Main(string[] args)
    {
        var hostBuilder = new HostBuilder()
             // Add configuration, logging, ...
            .ConfigureServices((hostContext, services) =>
            {
                // Add your services with depedency injection.
            });

        await hostBuilder.RunConsoleAsync();
    }
}

Answer 2

您应该在交互模式下运行容器(带-i选项).但请注意,当您运行容器时,后台进程将立即关闭,因此请确保您的脚本在前台运行,否则它将无法正常工作.

Answer 3

我可以让Docker/Linux保持我的.NET Core应用程序活着的唯一方法就是欺骗ASP.NET为我托管它...这是一个如此丑陋的黑客!

这样做将使用该docker run -d选项在Docker中运行,因此您不必具有实时连接以保持STDIN流存活.

我创建了一个.NET Core控制台应用程序(不是ASP.NET应用程序),我的Program类看起来像这样:

public class Program
{
    public static ManualResetEventSlim Done = new ManualResetEventSlim(false);
    public static void Main(string[] args)
    {
        //This is unbelievably complex because .NET Core Console.ReadLine() does not block in a docker container...!
        var host = new WebHostBuilder().UseStartup(typeof(Startup)).Build();

        using (CancellationTokenSource cts = new CancellationTokenSource())
        {
            Action shutdown = () =>
            {
                if (!cts.IsCancellationRequested)
                {
                    Console.WriteLine("Application is shutting down...");
                    cts.Cancel();
                }

                Done.Wait();
            };

            Console.CancelKeyPress += (sender, eventArgs) =>
            {
                shutdown();
                // Don't terminate the process immediately, wait for the Main thread to exit gracefully.
                eventArgs.Cancel = true;
            };

            host.Run(cts.Token);
            Done.Set();
        }
    }      
}

Startup类:

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSingleton<IServer, ConsoleAppRunner>();
    }


    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
    }
}

ConsoleAppRunner类

public class ConsoleAppRunner : IServer
{

    /// <summary>A collection of HTTP features of the server.</summary>
    public IFeatureCollection Features { get; }

    public ConsoleAppRunner(ILoggerFactory loggerFactory)
    {
        Features = new FeatureCollection();
    }

    /// <summary>Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.</summary>
    public void Dispose()
    {

    }

    /// <summary>Start the server with an application.</summary>
    /// <param name="application">An instance of <see cref="T:Microsoft.AspNetCore.Hosting.Server.IHttpApplication`1" />.</param>
    /// <typeparam name="TContext">The context associated with the application.</typeparam>
    public void Start<TContext>(IHttpApplication<TContext> application)
    {
        //Actual program code starts here...
        Console.WriteLine("Demo app running...");

        Program.Done.Wait();        // <-- Keeps the program running - The Done property is a ManualResetEventSlim instance which gets set if someone terminates the program.

    }
}

关于它的唯一好处是你可以在你的应用程序中使用DI(如果你愿意) - 所以在我的用例中,我使用ILoggingFactory来处理我的日志记录.

编辑2018年10月30日 这篇文章似乎仍然很受欢迎 - 我只想指出任何阅读我的旧帖子的人现在都很古老了.我的基础是.NET核心1.1(当时是新的).如果你使用更新版本的.NET核心(2.0/2.1或更高版本),那么现在可能有更好的方法来解决这个问题.请花些时间查看此主题上的其他一些帖子,这些帖子可能不如此排名高,但可能更新,更新.

Answer 4

您可以使用：

Thread.Sleep(Timeout.Infinite);

看到这个答案：

是 Thread.Sleep(Timeout.Infinite); 比 while(true){} 更有效率？