Previously I posted about using a Log4Net Appender to record Sitecore logs to Application Insights. That code will write Trace Messages to App Insights. I’m already filtering the messages to WARN or above using standard Log4Net <filter>s – but what if I need to filter more particular messages. Well, I wrote a telemetry processor to do this, just like Requests and Dependencies.

So, previously I’ve written about filtering out all the successful Dependency messages going to App Insights. What about unsuccessful ones, though?

My Sitecore instance seems have a failing dependency that is clogging up my logs. It’s the same as mentioned in this StackExchange question. It doesn’t seem to cause any issue, though… and it isn’t every environment either. Anyway, I’d like to block it. Telemetry processors to the rescue…

So, again, I’m trying to tame Application Insights. My logs are filling up with various requests for different health-check URLs. These get requested, over and over, day after day, and all are recorded in App Insights as Requests. However, I don’t care about these requests if they’re successful. In fact, I only care about if they fail. Can I exclude them?

Yes, I can. I’ll build a telemetry processor to filter them out.

Application Insights can record the performance of your dependencies – so things like requests to SQL server, MongoDB, etc.. That’s great – but it can become VERY verbose. I find frequently that most of my allocation of data is spent tracking every damn SQL statement run – and there could be hundreds in a single page load.

You can just turn on Dependency tracking completely – but that seems a bit of nuclear option. What if there IS a problem? I want to know about it!

Well, you can create your own Telemetry filter instead:

public class SuccessfulDependencyFilter : ITelemetryProcessor
{
	private readonly ITelemetryProcessor _nextProcessor;

	public SuccessfulDependencyFilter(ITelemetryProcessor nextProcessor)
	{
		_nextProcessor = nextProcessor;
	}

	public void Process(ITelemetry telemetry)
	{
		DependencyTelemetry dependencyTelemetry = telemetry as DependencyTelemetry;
		if (dependencyTelemetry != null)
		{
			if (dependencyTelemetry.Success == true )
			{
				return;					
			}
		}

		_nextProcessor.Process(telemetry);
	}
}

This ITelemetryProcessor will check if the telemetry is a successful Dependency, and if it is, end processing (i.e. don’t write anything to App Insights).

To use it, add it to the ApplicationInsights.config in the TelemetryProcessors section:

Obviously, this means that if you have problems like a slow dependency that is still eventually successful then you won’t have any telemetry to show you that – but it VASTLY reduces the data being captured.