Helper class to configure Application Insights and our Telemetry Processor

AppInsightsConfig.cs

using System.Configuration;
using Microsoft.ApplicationInsights.Extensibility;

namespace Samples.App_Start
{
	public static class AppInsightsConfig
	{
		public static void RegisterAppInsights()
		{
			TelemetryConfiguration.Active.InstrumentationKey =
				System.Web.Configuration.WebConfigurationManager.AppSettings["ApplicationInsightsKey"];

			var builder = TelemetryConfiguration.Active.TelemetryProcessorChainBuilder;
			builder.Use(next => new My404Filter(next));
			builder.Build();
		}
	}
}