c# - 在 ASP.NET Core 应用程序中使用 NLog

Question

我找到了CodeProject有一个如何让它工作的例子，但它不起作用。主要问题似乎是 Nuget 中似乎不存在 "Microsoft.Framework.Logging.NLog": "1.0.0-*" 包。我看过this StackOverflow question并查看了它引用的 GitHub 示例，但它似乎包含相同的问题。

我尝试让它自己工作，我想出的最好的方法如下:

public class NLogLogger : ILogger
{
    public NLogLogger()
    {
        new WebLoggerConfigurer().ConfigureDefault();
    }

    public void Log(LogLevel logLevel, int eventId, object state, Exception exception, Func<object, Exception, string> formatter)
    {
        // currently need the global:: for LogLevels because our namespace contains NLog in it. Is there a better naming convention we could use instead?
        var ll = logLevel == LogLevel.Debug ? global::NLog.LogLevel.Debug
                : logLevel == LogLevel.Verbose ? global::NLog.LogLevel.Trace
                : logLevel == LogLevel.Critical ? global::NLog.LogLevel.Fatal
                : logLevel == LogLevel.Error ? global::NLog.LogLevel.Error
                : logLevel == LogLevel.Information ? global::NLog.LogLevel.Info
                : logLevel == LogLevel.Warning ? global::NLog.LogLevel.Warn
                : global::NLog.LogLevel.Off;

        LogManager.GetCurrentClassLogger().Log(ll, formatter(state, exception));
    }

    public bool IsEnabled(LogLevel logLevel)
    {
        return true;
    }

    public IDisposable BeginScopeImpl(object state)
    {
        return new Disposable(() => { });
    }
}

public class NLogLoggerProvider : ILoggerProvider
{
    public void Dispose()
    {
    }

    public ILogger CreateLogger(string categoryName)
    {
        return new NLogLogger();
    }
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    loggerFactory.AddProvider(new NLogLoggerProvider());
    ..
}

BeginScopeImpl 的实现似乎是一个 hack，但我不确定如何最好地实现它。

1. 这看起来是一个有效的实现选项吗？
2. 是否有更好的方法来实现 BeginScopeImpl？
3. 还有其他方法让 NLog 与 ASP.NET Core 配合使用吗？

Answer 1

对于 ASP.NET Core，您需要 NLog.Web.AspNetCore - 这依赖于 NLog.Extensions.Logging .

注意:Microsoft.Framework.Logging.NLog 已替换为 NLog.Extensions.Logging on NuGet ，由 NLog 团队维护。

使用方法:

设置

需要启用 NLog，以便将其集成到 ASP.NET Core 的 DI 和日志 API 中。这将导致外部(例如 Microsoft)写入的所有日志也将发送到 NLog - 您可以在 NLog 的配置中过滤掉它(不会影响性能)。

ASP.NET Core 1

在 ASP.NET Core 中的 Configure 和可选的 ConfigureServices 需要更新。

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    //add NLog to .NET Core
    loggerFactory.AddNLog();

    //Enable ASP.NET Core features (NLog.web) - only needed for ASP.NET Core users
    app.AddNLogWeb();

    //configure nlog.config in your project root. 
    env.ConfigureNLog("nlog.config");
    ...
    //you could use LogManager.Configuration from here


public void ConfigureServices(IServiceCollection services)
{
    // Add framework services.
    // e.g. services.AddMvc();

    //needed for NLog.Web
    services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
}

ASP.NET Core 2

对于 ASP.NET Core 2，设置与 ASP.NET Core 1 不同

在program.cs中设置NLog:

using NLog.Web;
using Microsoft.Extensions.Logging;

public static void Main(string[] args)
{
    // NLog: setup the logger first to catch all errors
    var logger = NLog.Web.NLogBuilder.ConfigureNLog("nlog.config").GetCurrentClassLogger();
    try
    {
        logger.Debug("init main");
        CreateWebHostBuilder(args).Build().Run(); 
    }
    catch (Exception ex)
    {
        //NLog: catch setup errors
        logger.Error(ex, "Stopped program because of exception");
        throw;
    }
    finally
    {
        // Ensure to flush and stop internal timers/threads before application-exit (Avoid segmentation fault on Linux)
        NLog.LogManager.Shutdown();
    }
}

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
    WebHost.CreateDefaultBuilder(args)
        .UseStartup<Startup>()
        .ConfigureLogging(logging =>
        {
            logging.ClearProviders();
            logging.SetMinimumLevel(Microsoft.Extensions.Logging.LogLevel.Trace);
        })
        .UseNLog();  // NLog: setup NLog for Dependency injection

ASP.NET Core 3 和 5

与 ASP.NET Core 2 相比，有一些小的变化，例如有一个 IHostBuilder 而不是 IWebHostBuilder。

对于 ASP.NET Core 5，步骤是相同的​​。

在program.cs中设置NLog:

using System;
using NLog.Web;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Hosting;

public static void Main(string[] args)
{
    var logger = NLog.Web.NLogBuilder.ConfigureNLog("nlog.config").GetCurrentClassLogger();
    try
    {
        logger.Debug("init main");
        CreateHostBuilder(args).Build().Run();
    }
    catch (Exception exception)
    {
        //NLog: catch setup errors
        logger.Error(exception, "Stopped program because of exception");
        throw;
    }
    finally
    {
        // Ensure to flush and stop internal timers/threads before application-exit (Avoid segmentation fault on Linux)
        NLog.LogManager.Shutdown();
    }
}

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
      .ConfigureWebHostDefaults(webBuilder =>
      {
          webBuilder.UseStartup<Startup>();
      })
      .ConfigureLogging(logging =>
      {
          logging.ClearProviders();
          logging.SetMinimumLevel(Microsoft.Extensions.Logging.LogLevel.Trace);
      })
      .UseNLog();  // NLog: Setup NLog for Dependency injection

ASP.NET Core 6

对于 ASP.NET Core 6，您可以在没有 Startup 类的情况下配置它。更新 Program.cs 如下:

using NLog;
using NLog.Web;

var logger = NLog.LogManager.Setup().LoadConfigurationFromAppSettings().GetCurrentClassLogger();
logger.Debug("init main");

try
{
    var builder = WebApplication.CreateBuilder(args);

    // Add services to the container.
    builder.Services.AddControllersWithViews();

    // NLog: Setup NLog for Dependency injection
    builder.Logging.ClearProviders();
    builder.Logging.SetMinimumLevel(Microsoft.Extensions.Logging.LogLevel.Trace);
    builder.Host.UseNLog();

    var app = builder.Build();

    // Configure the HTTP request pipeline.
    if (!app.Environment.IsDevelopment())
    {
        app.UseExceptionHandler("/Home/Error");
        // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
        app.UseHsts();
    }

    app.UseHttpsRedirection();
    app.UseStaticFiles();

    app.UseRouting();

    app.UseAuthorization();

    app.MapControllerRoute(
        name: "default",
        pattern: "{controller=Home}/{action=Index}/{id?}");

    app.Run();
}
catch (Exception exception)
{
    // NLog: catch setup errors
    logger.Error(exception, "Stopped program because of exception");
    throw;
}
finally
{
    // Ensure to flush and stop internal timers/threads before application-exit (Avoid segmentation fault on Linux)
    NLog.LogManager.Shutdown();
}

写入日志

使用类类型作为通用参数注入(inject) ILogger。

public class HomeController : Controller
{
    public HomeController(ILogger<HomeController> logger)
    {
        logger.LogInformation("created homeController");
    }

配置NLog规则

有关如何配置、记录和过滤的示例。

创建一个 nlog.config(有关 nlog.config 的更多信息，请参阅 docs)。

此示例将创建 2 个文件，一个包含所有日志(包括 Microsoft 的日志)，另一个文件仅包含您的日志。

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        autoReload="true"
        internalLogLevel="Warn"
        internalLogFile="c:\temp\internal.txt">


    <extensions>
        <!--enable NLog.Web for ASP.NET Core-->
        <add assembly="NLog.Web.AspNetCore"/>
    </extensions>

    <!-- define various log targets -->
    <targets>
        <!-- write logs to file -->
        <target xsi:type="File" name="allfile" fileName="c:\temp\nlog-all-${shortdate}.log"
                        layout="${longdate}|${logger}|${uppercase:${level}}|${message} ${exception}" />

        <target xsi:type="File" name="ownFile" fileName="c:\temp\nlog-own-${shortdate}.log"
                    layout="${longdate}|${logger}|${uppercase:${level}}|${message} ${exception}" />

    </targets>

    <rules>
        <!--All logs, including from Microsoft-->
        <logger name="*" minlevel="Trace" writeTo="allfile" />

        <!--Skip Microsoft logs - no writeTo attribute-->
        <logger name="Microsoft.*" minlevel="Trace" final="true" />
        <logger name="*" minlevel="Trace" writeTo="ownFile" />
    </rules>
</nlog>

发布nlog.config

这不是 ASP.NET Core 5 必需的步骤

确保 nlog.config 将被发布，例如在您的 csproj 文件中:

<ItemGroup>
    <Content Update="nlog.config" CopyToOutputDirectory="PreserveNewest" />
</ItemGroup>

输出

“nlog-own-2018-02-14.log”包含:

2018-02-14 16:27:04.0547|aspnetCoreApplication.Controllers|INFO|created homeController

2018-02-14 16:27:04.0547|aspnetCoreApplication.Controllers|INFO|created homeController

疑难解答

ASP.NET Core 2 中缺少调试日志消息？虽然我们在program.cs中使用SetMinimumLevel，但appsettings.json也可以对此进行融合。

您可以按如下方式更改:

更改appsettings.json:

{
    "Logging": {
        "LogLevel": {
            "Default": "Trace"
        }
    }
}

您还可以在此处过滤 Microsoft 的日志，例如

{
    "Logging": {
        "LogLevel": {
            "Default": "Trace",
            "Microsoft": "Information"
        }
    }
}

其他问题，请参见此步骤计划查找原因: Logging-troubleshooting in NLog

干杯，

朱利安(NLog)

编辑:针对 NLog.Web.AspNetCore 4.3 进行了更新

编辑 2:更新了 ASP.NET Core 2 和最新建议

编辑 3:针对 ASP.NET Core 3 进行了更新

编辑 4:针对 ASP.NET Core 5 进行了更新

编辑 5:针对 ASP.NET Core 6 进行了更新