抛出未处理的异常时阻止 Microsoft Logging 从日志中记录

Question

我有 ASP.NET Core 3.0 网站。
我在项目上安装了NLog，这里是配置

public static void Main(string[] args)
{
    var logger = NLogBuilder.ConfigureNLog("nlog.config").GetCurrentClassLogger();
    BuildWebHost(args).Run();
}

public static IWebHost BuildWebHost(string[] args)
{
    return WebHost.CreateDefaultBuilder(args)
        .ConfigureLogging(logging =>
        {
            logging.ClearProviders();
            logging.SetMinimumLevel(Microsoft.Extensions.Logging.LogLevel.Trace);
        })
        .UseNLog()
        .UseStartup<Startup>()
        .UseUrls("http://*:8080")
        .Build();
}



public class Startup
{
    // some constructors

    public void ConfigureServices(IServiceCollection services)
    {
        var serviceProvider = services.BuildServiceProvider();
        var logger = serviceProvider.GetService<ILogger<object>>();
        services.AddSingleton<ILogger>(logger);
    }
}

nlog.config 文件是

<?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="false"
      throwExceptions="true"
      internalLogLevel="Off">

  <extensions>
    <add assembly="NLog.Web.AspNetCore"/>
  </extensions>

  <variable name="sperator" value="-----------------------------------" />

  <targets>
    <target name="allfile"
            xsi:type="File"
            fileName="${basedir}/Logs/${date:format=yyyy-MM-dd}.log"
            archiveEvery="Day"
            archiveFileName="${basedir}/Logs/Log${shortdate}-{#}.log"
            archiveNumbering="Sequence"
            layout="eventId : ${event-properties:item=EventId_Name}${newline}${message} ${newline} ${sperator} ${newline}" />

  </targets>

  <!-- rules to map from logger name to target -->
  <rules>
    <logger name="*" minlevel="Trace" writeTo="allfile" />
  </rules>
</nlog>

appsettings.config

"Logging": {
    "LogLevel": {
      "Default": "Trace",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },

最后一件事我有一个中间件来处理从应用程序各处抛出的所有异常

public class ExceptionMiddleware
{
    private readonly RequestDelegate _next;
    private readonly ILogger _logger;

    public ExceptionMiddleware(RequestDelegate next, ILogger logger)
    {
        _next = next;
        _logger = logger;
    }

    public async Task Invoke(HttpContext context)
    {
        context.Response.Clear();
        context.Response.ContentType = "application/json";

        var contextFeature = context.Features.Get<IExceptionHandlerFeature>();
        if (contextFeature == null)
            return;

        string jsonResult = "";

        context.Response.StatusCode = (int)HttpStatusCode.InternalServerError;

        EventId eventId = new EventId(0, Guid.NewGuid().ToString());
        _logger.LogError(eventId, message: $"Date : {DateTime.Now.ToString()} \nPath : {context.Request.Path} \nStackTrace: {contextFeature.Error.ToString()}");

        jsonResult = JsonConvert.SerializeObject(new
        {
           ErrorMessage = contextFeature.Error.Message,
           StackTrace = contextFeature.Error.StackTrace
        });

        await context.Response.WriteAsync(jsonResult);
    }
}

问题是

当我抛出异常时，我在日志文件中得到两条日志（即使我只记录一次）
我现在确信第一个是由 Asp.NET CORE 自动完成的，因为异常被认为是未处理的异常（即使存在处理异常的中间件）

这是我得到的日志

eventId : UnhandledException
An unhandled exception has occurred while executing the request. 
 ----------------------------------- 

eventId : 88e05695-fc66-4d99-8537-aba8f0fa211b
Date : 1/1/2020 5:09:17 PM 
Path : /api/AppParameter/ThrowException 
StackTrace: System.Exception: this exception has been throw for testing the NLog
   at BT_IQM.Services.WebApi.Controllers.AppParameterController.ThrowException() in C:\Users\BitegPC\Source\Repos\BT_Backend_Architecture\BT_IQM.Services.WebApi\Controllers\AppParameterController.cs:line 80
   at lambda_method(Closure , Object , Object[] )
   at Microsoft.Extensions.Internal.ObjectMethodExecutor.Execute(Object target, Object[] parameters)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.SyncActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeActionMethodAsync()
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeNextActionFilterAsync()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at BT_IQM.Services.WebApi.Utility.LanguageMiddleware.Invoke(HttpContext context) in C:\Users\BitegPC\Source\Repos\BT_Backend_Architecture\BT_IQM.Services.WebApi\Utility\LanguageMiddlewareExtensions.cs:line 27
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task) 
 -----------------------------------

第二个日志正是我在中间件中记录的内容，但我的问题在第一个日志中（我根本不想显示），第二个日志对我来说就足够了

我认为我的问题出在日志记录的配置中（特别是在 appsettings.config 文件中）

更新

这里是注册异常中间件的扩展方法

public static class ExceptionMiddlewareExtensions
{
    public static void ConfigureExceptionHandler(this IApplicationBuilder app, ILogger logger)
    {
        app.UseExceptionHandler(appError => appError.UseMiddleware<ExceptionMiddleware>());
    }
}

这是整个配置方法

public void Configure(IApplicationBuilder app, IWebHostEnvironment env, ILogger logger
{
    app.ConfigureExceptionHandler(logger);
    app.ConfigureLanguageMiddleware();

    app.UseRouting();
    app.UseAuthentication();
    app.UseAuthorization();

    app.UseEndpoints(endpoints =>
    {
        endpoints.MapControllers();
    });

    app.UseSwagger();
    app.UseSwaggerUI(c =>
    {
        c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");
    });
}

Answer 1

app.UseExceptionHandler(appError => appError.UseMiddleware<ExceptionMiddleware>());

好的，这里的问题是您正在使用 ASP.NET Core 附带的 ExceptionHandlerMiddleware。这个中间件负责捕获异常，然后按照您配置的方式处理它。

您使用它的方式是将一个异常处理程序应用程序管道传递给它，您可以在其中运行您自己的中间件，然后生成结果。

现在，如果您查看 the source of the ExceptionHandlerMiddleware，您会发现这就是它最终捕获异常并调用其异常处理程序的方式：

ExceptionDispatchInfo edi;
try
{
    var task = _next(context);
    // …
    return Task.CompletedTask;
}
catch (Exception exception)
{
    edi = ExceptionDispatchInfo.Capture(exception);
}

return HandleException(context, edi);

所以它运行是中间件管道，只捕获任何异常，最后运行是 HandleException 如果到目前为止。这是 HandleException 做的第一件事：

private async Task HandleException(HttpContext context, ExceptionDispatchInfo edi)
{
    _logger.UnhandledException(edi.SourceException);
    // …

    // much later then:
    await _options.ExceptionHandler(context);

    // …
}

因此它会记录它捕获了一个未处理的异常，甚至在进一步查看异常并最终调用配置的异常处理程序之前，该异常处理程序随后将调用您的自定义中间件。

最后，您将无法阻止此日志记录，因此您现在有三个选择：

通过Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware过滤键显式过滤掉日志。这可以在不更改 appsettings.json 中的代码的情况下完成。有关详细信息，请参阅 log filtering 上的文档：
```
"Logging": {
  "LogLevel": {
    "Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware": "None"
  }
}
```
从您的中间件中删除日志并仅使用现有日志。
不要将您的中间件作为 ExceptionHandlerMiddleware 的一部分调用，而是使其成为一个普通的中间件，它本身会捕获异常，然后可以做任何您想做的事情。

抛出未处理的异常时阻止 Microsoft Logging 从日志中记录

Prevent Microsoft Logging from log when Unhandled exception thrown

c#

nlog

asp.net-core