Add option to exception handler middleware to not log error

Author: JamesNK

src/Middleware/Diagnostics/src/DeveloperExceptionPage/DeveloperExceptionPageMiddlewareImpl.cs

@@ -115,6 +115,8 @@ public async Task Invoke(HttpContext context)
         }
         catch (Exception ex)
         {
+            DiagnosticsTelemetry.AddMetricsTags(context, ex);
+
             var exceptionName = ex.GetType().FullName!;
 
             if ((ex is OperationCanceledException || ex is IOException) && context.RequestAborted.IsCancellationRequested)
@@ -135,8 +137,6 @@ public async Task Invoke(HttpContext context)
                 return;
             }
 
-            DiagnosticsTelemetry.ReportUnhandledException(_logger, context, ex);
-
             if (context.Response.HasStarted)
             {
                 _logger.ResponseStartedErrorPageMiddleware();

src/Middleware/Diagnostics/src/DiagnosticsTelemetry.cs

@@ -3,16 +3,13 @@
 
 using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Http;
-using Microsoft.Extensions.Logging;
 
 namespace Microsoft.AspNetCore.Diagnostics;
 
 internal static class DiagnosticsTelemetry
 {
-    public static void ReportUnhandledException(ILogger logger, HttpContext context, Exception ex)
+    public static void AddMetricsTags(HttpContext context, Exception ex)
     {
-        logger.UnhandledException(ex);
-
         if (context.Features.Get<IHttpMetricsTagsFeature>() is { } tagsFeature)
         {
             // Multiple exception middleware could be registered that have already added the tag.

src/Middleware/Diagnostics/src/ExceptionHandler/ExceptionHandlerMiddlewareImpl.cs

@@ -112,10 +112,13 @@ static async Task Awaited(ExceptionHandlerMiddlewareImpl middleware, HttpContext
 
     private async Task HandleException(HttpContext context, ExceptionDispatchInfo edi)
     {
+        DiagnosticsTelemetry.AddMetricsTags(context, edi.SourceException);
+
         var exceptionName = edi.SourceException.GetType().FullName!;
 
         if ((edi.SourceException is OperationCanceledException || edi.SourceException is IOException) && context.RequestAborted.IsCancellationRequested)
         {
+            // Don't log unhandled exception for aborted request.
             _logger.RequestAbortedException();
 
             if (!context.Response.HasStarted)
@@ -127,11 +130,10 @@ private async Task HandleException(HttpContext context, ExceptionDispatchInfo ed
             return;
         }
 
-        DiagnosticsTelemetry.ReportUnhandledException(_logger, context, edi.SourceException);
-
         // We can't do anything if the response has already started, just abort.
         if (context.Response.HasStarted)
         {
+            _logger.UnhandledException(edi.SourceException);
             _logger.ResponseStartedErrorHandler();
 
             _metrics.RequestException(exceptionName, ExceptionResult.Skipped, handler: null);
@@ -201,6 +203,7 @@ private async Task HandleException(HttpContext context, ExceptionDispatchInfo ed
                     }
                 }
             }
+
             // If the response has already started, assume exception handler was successful.
             if (context.Response.HasStarted || handled || _options.StatusCodeSelector != null || context.Response.StatusCode != StatusCodes.Status404NotFound || _options.AllowStatusCode404Response)
             {
@@ -210,10 +213,18 @@ private async Task HandleException(HttpContext context, ExceptionDispatchInfo ed
                     WriteDiagnosticEvent(_diagnosticListener, eventName, new { httpContext = context, exception = edi.SourceException });
                 }
 
+                if (!_options.SuppressLoggingOnHandledException)
+                {
+                    _logger.UnhandledException(edi.SourceException);
+                }
+
                 _metrics.RequestException(exceptionName, ExceptionResult.Handled, handler);
                 return;
             }
 
+            // Log original unhandled exception before it is wrapped.
+            _logger.UnhandledException(edi.SourceException);
+
             edi = ExceptionDispatchInfo.Capture(new InvalidOperationException($"The exception handler configured on {nameof(ExceptionHandlerOptions)} produced a 404 status response. " +
                 $"This {nameof(InvalidOperationException)} containing the original exception was thrown since this is often due to a misconfigured {nameof(ExceptionHandlerOptions.ExceptionHandlingPath)}. " +
                 $"If the exception handler is expected to return 404 status responses then set {nameof(ExceptionHandlerOptions.AllowStatusCode404Response)} to true.", edi.SourceException));
@@ -222,6 +233,9 @@ private async Task HandleException(HttpContext context, ExceptionDispatchInfo ed
         {
             // Suppress secondary exceptions, re-throw the original.
             _logger.ErrorHandlerException(ex2);
+
+            // There was an error handling the exception. Log original unhandled exception.
+            _logger.UnhandledException(edi.SourceException);
         }
         finally
         {

src/Middleware/Diagnostics/src/ExceptionHandler/ExceptionHandlerOptions.cs

@@ -40,10 +40,17 @@ public class ExceptionHandlerOptions
     public bool AllowStatusCode404Response { get; set; }
 
     /// <summary>
-    /// Gets or sets a delegate used to map an exception to a http status code.
+    /// Gets or sets a delegate used to map an exception to an HTTP status code.
     /// </summary>
     /// <remarks>
     /// If <see cref="StatusCodeSelector"/> is <c>null</c>, the default exception status code 500 is used.
     /// </remarks>
     public Func<Exception, int>? StatusCodeSelector { get; set; }
+
+    /// <summary>
+    /// Gets or sets a value that determines if the exception handler middleware should suppress logging
+    /// if the exception was handled by either <see cref="ExceptionHandler"/>, <see cref="IProblemDetailsService"/> or
+    /// <see cref="IExceptionHandler"/> registered in the DI container.
+    /// </summary>
+    public bool SuppressLoggingOnHandledException { get; set; }
 }

src/Middleware/Diagnostics/src/PublicAPI.Unshipped.txt

@@ -1 +1,3 @@
 #nullable enable
+Microsoft.AspNetCore.Builder.ExceptionHandlerOptions.SuppressLoggingOnHandledException.get -> bool
+Microsoft.AspNetCore.Builder.ExceptionHandlerOptions.SuppressLoggingOnHandledException.set -> void