(Asp.Net core 3.1/.Net 6) I need to disable the ERR logging of exception TaskCanceledException in an Asp.Net application (built by others). I've used the following middleware to suppress the TaskCanceledException

app.UseMiddleware<TaskCanceledMiddleware>();

public class TaskCanceledMiddleware
{
    private readonly RequestDelegate _next;

    public TaskCanceledMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        try
        {
            await _next(context);
        }
        catch (TaskCanceledException)
        {
            // Set StatusCode 499 Client Closed Request
            logger.WARN("...")
            context.Response.StatusCode = 499;
        }
    }
}

I can see the WARN log in the logs. However, I can still find the following EROR messages by Serilog.AspNetCore.RequestLoggingMiddleware? (Note the error level is EROR)

2022-07-06 07:30:40.6636|116344477|EROR|Serilog.AspNetCore.RequestLoggingMiddleware|HTTP "GET" "/api/v1/myurl" responded 500 in 23213.3233 ms
System.Threading.Tasks.TaskCanceledException: A task was canceled.
   at System.Net.Http.DiagnosticsHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
   at ....

Why there is still errors of TaskCanceledException after using app.UseMiddleware<TaskCanceledMiddleware>()? (BTW, what's the level of EROR? Shouldn't it be ERR?)

CodePudding user response：

do you know where the exception is thrown? Maybe it throws not inside asp.net core action execution pipeline (where Middleware works). You can register a filter to intercept application wide exceptions inside .AddControllers() registration like this:

 _ = services
        .AddControllers(options =>
        {
            //Global filters
            _ = options.Filters.Add<ApiGlobalExceptionFilterAttribute>();
            ///...omissis...
        })

Here a simple exception filter attribute implementation:

public sealed class ApiGlobalExceptionFilterAttribute : ExceptionFilterAttribute
{
    private readonly ILogger<ApiGlobalExceptionFilterAttribute> _logger;

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

    public override void OnException(ExceptionContext context)
    {
        var request = context.HttpContext?.Request;

        if (context.Exception is TaskCanceledException tcExc)
        {
            // Set StatusCode 499 Client Closed Request
            _logger.WARN("...");
            context.Result = new ErrorActionResult(499);
        }
        else
        {
            //TODO: manage errors
        }

        context.ExceptionHandled = true;

        base.OnException(context);
    }
}

internal class ErrorActionResult : IActionResult
{
    [JsonIgnore]
    public int StatusCode { get; private set; }

    public ErrorActionResult(int statusCode)
    {
        StatusCode = statusCode;
    }

    public async Task ExecuteResultAsync(ActionContext context)
    {
        var error = new
        {
            Code = StatusCode,
            Message = "Internal server error"
        };

        var objectResult = new ObjectResult(error)
        {
            StatusCode = StatusCode
        };

        await objectResult.ExecuteResultAsync(context);
    }
}

The context.ExceptionHandled = true; stops exception to be propagated inside pipeline.

Hope it helps!

CodePudding user response：

you can try excluding logging for certain exception like this.

new LoggerConfiguration()
       ....
       .Filter.ByExcluding(logEvent => logEvent.Exception != null && logEvent.Exception.GetType() == typeof(TaskCanceledException))
       ...CreateLogger();