Boilerplate context initializers for Applicaiton Inisghts.

ApplicationInsightsContextInit.cs

public class ApplicationInsightsContextInit : IContextInitializer
{
    private const string DefaultApplicationSection = "SectionDefault";

    private readonly Dictionary<string, string> _pathToSection = new Dictionary<string, string>()
    {
        {   "/section1", "Section1" },
        {   "/section2", "Section2" },
    };

    public string InstrumentationKey { get; private set; }
    public string ApplicationEnvironment { get; private set; }
    public string ApplicationVersion { get; private set; }

    public ApplicationInsightsContextInit(string instrumentationKey, string applicationEnvironment)
    {
        InstrumentationKey = instrumentationKey;
        ApplicationEnvironment = applicationEnvironment;
        ApplicationVersion = GetCurrentVersion();
    }
    
    public static string GetCurrentVersion()
    {
        return System.Reflection.Assembly.GetExecutingAssembly().GetName().Version.ToString();
    }

    public void Initialize(TelemetryContext context)
    {
        context.InstrumentationKey = InstrumentationKey;
        context.Component.Version = ApplicationVersion;

        context.Properties["ApplicationEnvironment"] = ApplicationEnvironment;
        context.Properties["ApplicationSection"] = GetApplicationSection();
        context.Properties["RequestHttpMethod"] = GetCurrentHttpMethod();
    }

    private string GetCurrentHttpMethod()
    {
        if (HttpContext.Current == null)
        {
            return string.Empty;
        }

        return HttpContext.Current.Request.HttpMethod;
    }

    private string GetApplicationSection()
    {
        if (HttpContext.Current == null)
        {
            return string.Empty;
        }

        var path = HttpContext.Current.Request.Path;
        var section = _pathToSection.FirstOrDefault(x => path.StartsWith(x.Key, StringComparison.OrdinalIgnoreCase)).Value;
        if (string.IsNullOrWhiteSpace(section))
        {
            section = DefaultApplicationSection;
        }

        return section;
    }
}

ApplicationInsightsContextTelemtryInit.cs

public class ApplicationInsightsContextTelemtryInit : ApplicationInsightsContextInit, ITelemetryInitializer
{
    public ApplicationInsightsContextTelemtryInit(string instrumentationKey, string applicationEnvironment) : base(instrumentationKey, applicationEnvironment)
    {
    }

    public void Initialize(ITelemetry telemetry)
    {
        base.Initialize(telemetry.Context);
    }
}

Global.asax.cs

public class Global : HttpApplication
{
  protected void Application_Start(object sender, EventArgs e)
  {
      InitApplicationInsights();
  }
  
  private static void InitApplicationInsights()
  {
      var telemetryConfiguration = TelemetryConfiguration.Active;
  
      var appInsightsInstrumentationKey = ConfigurationManager.AppSettings.Get("ApplicationInsights.InstrumentationKey");
      var appInsightsEnvironment = ConfigurationManager.AppSettings.Get("ApplicationInsights.Environment");
      var isValidKey = !string.IsNullOrWhiteSpace(appInsightsInstrumentationKey);
      
      if (isValidKey)
      {
          telemetryConfiguration.DisableTelemetry = false;
          telemetryConfiguration.ContextInitializers.Add(new ApplicationInsightsContextInit(appInsightsInstrumentationKey, appInsightsEnvironment));
          telemetryConfiguration.TelemetryInitializers.Add(new ApplicationInsightsContextTelemtryInit(appInsightsInstrumentationKey, appInsightsEnvironment));
      }
      else
      {
          telemetryConfiguration.DisableTelemetry = true;
      }
  }
}