Telemetry Initializer to add request body content from .net core MVC app to request telemetry properties not working

Question

I'm trying to integrate application insights to .net core MVC application. Everything worked as expected till I added a telemetry initializer to read request body content. I created a ITelemetryInitializer which reads the content from the request body if the telemetry type is request telemetry. But i'm getting "System.ObjectDisposedException: 'Cannot access a disposed object.'"

Issue:

On debugging I noticed, when a POST/PUT http call is made, MVC action method is invoked before Initialize() method. So by the time the Initialize() method is invoked, request body request stream is already disposed. I've a similar implementation for 4.6 framework web api application, but its works fine without this issue.

Is there a way I can invoke the initializers before MVC action is executed. I tried configuring application insights with IWebHostBuilder and IServiceCollection.

Did anyone come across this issue?

Version Info SDK Version : 2.2.1 .NET Version : .Net core 2.0 How Application was onboarded with SDK(VisualStudio/StatusMonitor/Azure Extension) : OS : Hosting Info (IIS/Azure WebApps/ etc) : IIS

Update (copied code from comment):

if (!(telemetry is RequestTelemetry requestTelemetry))
   return;
var request = _httpContextAccessor.HttpContext?.Request;
if (request == null)
   return;
if (request.Body.CanRead)
{
   request.EnableRewind();
   using (var memoryStream = new MemoryStream())
   { 
      request.Body.CopyTo(memoryStream);
      request.Body.Position = 0; //add to telemetry properties
   }
}

To re-read the request body you need to "EnableBuffering" devblogs.microsoft.com/aspnet/… — Aaron Hoffman

cijothomas cijothomas · Accepted Answer · 2018-05-11T17:09:14

I replied to your post in Github as well. Here's the correct way of enriching telemetry with information from Http Post/Put request body. This is a controller Post Action, and the RequestTelemetry is enriched with information from the post body.

[HttpPost]
        public IActionResult Create([FromBody] TodoItem item)
        {
            if (item == null)
            {
                return BadRequest();
            }

            RequestTelemetry requestTelemetry = HttpContext.Features.Get<RequestTelemetry>();
            requestTelemetry.Properties.Add("nameFromBody", item.Name);

            _context.TodoItems.Add(item);
            _context.SaveChanges();

            return CreatedAtRoute("GetTodo", new { id = item.Id }, item);
        }

Telemetry Initializer to add request body content from .net core MVC app to request telemetry properties not working

1 Answers