Custom Telemetry Processor not loading

Question

I've written a small Telemetry Processor to filter out some HTTP 404 which are not an issue for my application. I've been following Microsoft's doc on this process.

I have created a new class implementing ITelemetryProcessor and setup the constructor and process function.

namespace My_App
{
    class WebJobQueuesDependencyFilter : ITelemetryProcessor
    {
        private ITelemetryProcessor Next { get; set; }

        // Link processors to each other in a chain.
        public WebJobQueuesDependencyFilter(ITelemetryProcessor next)
        {
            this.Next = next;
        }

        public void Process(ITelemetry item)
        {
            var request = item as RequestTelemetry;

            if (request != null &&
            request.ResponseCode.Equals("404", StringComparison.OrdinalIgnoreCase))
            {
                // To filter out an item, just terminate the chain:
                return;
            }
            // Send everything else:
            this.Next.Process(item);
        }
    }
}

I have also added a new line to my ApplicationInsights.config under <TelemetryProcessors>

<Add Type="My_App.WebJobQueuesDependencyFilter, My_App" />

Upon starting my program I see the following message recorded in AI in Visual Studio.

AI: ApplicationInsights configuration file loading failed. Type 'My_App.WebJobQueuesDependencyFilter, My_App' was not found. Type loading was skipped. Monitoring will continue.

I suspect the issue lies with the line in config. Microsoft's docs don't seem to detail exactly what that line should contain. My guess based on MS example is the namespaced path to the filter class and the namespace for my application.

The type should contain the namespace followed by class name (i.e My_App.WebJobQueuesDependencyFilter) and then the assembly name so make sure your app is My_App. If this still doesn't work, how about initializing the TelemetryProcessor directly instead of using the config, as shown here i.e builder.Use((next) => new WebJobQueuesDependencyFilter(next)) — degant

degant degant · Accepted Answer · 2017-05-11T21:30:58

You probably forgot to mark the class public so the type isn't being found. Update your telemetry processor as public:

public class WebJobQueuesDependencyFilter : ITelemetryProcessor

Also, the correct way to specify the type includes the fully qualified name of your telemetry processor followed by the assembly name. So in your example the assembly name must be My_App

<!-- Fully qualified type name, assembly name: -->
<Add Type="My_App.WebJobQueuesDependencyFilter, My_App" />

Hope this helps!

Custom Telemetry Processor not loading

2 Answers