Raygun integration for webjobs

BAREBONES_RaygunExceptionHandler.cs

public static class RaygunExceptionHandler
  {
    private static readonly RaygunClient _client;

    static RaygunExceptionHandler()
    {
      _client = new RaygunClient("your_apikey");
      _client.AddWrapperExceptions(typeof(FunctionInvocationException));
    }

    public static void Process(TraceFilter filter)
    {
      var events = filter.GetEvents().Where(e => e.Exception != null);
      foreach (var traceEvent in events)
      {
        _client.Send(traceEvent.Exception);
      }
    }
  }

explanation.txt

Tested on 3/3/2017 with following packages:
Microsoft.Azure.WebJobs version 2.0.0
Mindscape.Raygun4Net version 5.4.1

The old solution outlined at https://raygun.com/blog/2015/02/setting-raygun-azure-webjobs/ does not work because the Function Executor of the Azure Webjobs catches and handles exceptions, so they never bubble up as a unhandled exception.

The solution is to use the Web Jobs trace module, which allows for registering a custom exception handler.

For this, we create a static ExceptionHandler class that will process exceptions for us.

The Program.cs is the default file created from adding a new web job project. Only the code between // -- Raygun Exception Handling BEGIN and // -- Raygun Exception Handling END was added.

I added a barebones example and a extended example that collects more useful information.

EXTENDED_RaygunExceptionHandler.cs

  /// <summary>
  /// Captures and sends exceptions to Raygun for reporting and analysis.  
  /// </summary>
  public static class RaygunExceptionHandler
  {
    private static readonly RaygunClient _client;

    static RaygunExceptionHandler()
    {
      _client = new RaygunClient("your_apikey");
      _client.AddWrapperExceptions(typeof(FunctionInvocationException));
    }

    /// <summary>
    /// Process Web Job Function Invocation Exceptions
    /// </summary>
    /// <param name="filter">The <see cref="TraceFilter"/> containing information about the exception.</param>
    public static void Process(TraceFilter filter)
    {
      // Get Web Job scm Host URI: yoursite.scm.azurewebsites.net
      var httpHost = Environment.GetEnvironmentVariable("HTTP_HOST");

      var events = filter.GetEvents().Where(e => e.Exception != null);
      foreach (var traceEvent in events)
      {
        var tags = new List<string>();

        // Add all trace properties to custom data
        var customData = traceEvent.Properties.ToDictionary(traceEventProperty => traceEventProperty.Key, traceEventProperty => traceEventProperty.Value);

        // If the FunctionInvocationId is available to us, we can use it to build a clickable link using the http host
        if (traceEvent.Properties.ContainsKey("MS_FunctionInvocationId") && !string.IsNullOrEmpty(httpHost))
        {
          var functionInvocationId = traceEvent.Properties["MS_FunctionInvocationId"];
          customData["Dashboard URL"] = $"https://{httpHost}/azurejobs/#/functions/invocations/{functionInvocationId}";
        }

        // If the FunctionDescriptor is available to us, we can use it to tag the executed function in raygun
        if (traceEvent.Properties.ContainsKey("MS_FunctionDescriptor"))
        {
          var functionDescriptor = (FunctionDescriptor)traceEvent.Properties["MS_FunctionDescriptor"];
          tags.Add(functionDescriptor.ShortName);
        }

        _client.Send(traceEvent.Exception, tags, customData);
      }
    }
  }

Program.cs

  // To learn more about Microsoft Azure WebJobs SDK, please see http://go.microsoft.com/fwlink/?LinkID=320976
  class Program
  {
    // Please set the following connection strings in app.config for this WebJob to run:
    // AzureWebJobsDashboard and AzureWebJobsStorage
    static void Main()
    {
      var config = new JobHostConfiguration();
      
      // -- Raygun Exception Handling BEGIN
      var traceMonitor = new TraceMonitor()
        .Filter(p => p.Exception != null, "Exception Handler")
        .Subscribe(RaygunExceptionHandler.Process);

      config.Tracing.Tracers.Add(traceMonitor);
      // -- Raygun Exception Handling END
      
      var host = new JobHost(config);
      
      host.RunAndBlock();
    }
  }

raygun_extended.png