Enable Access to Dependency Request Objects in DependencyCollector

[michaelwstark]

Opening this item per comments on the pull request -- consolidating discussions referenced items.

#issues:
#820
#747
#587
#897

Please reference the issues and pull request for additional details and\or discussion.

Consumers of the dependency collection package would like to be able to populate additional data in the tracked telemetry through implementing ITelemetryInitializer classes. At present, this is not possible given only the data passed in the call to Initialize() is the dependency telemetry item itself with pre-defined fields populated from within the dependency collector.

The ask is to track key data in the dependency collection and provide access to it as part of the ITelemetry item passed to the initializers.

Here is a sample of intended use -- reporting a debug-id value from an http response:

public class SampleTelemetryInitializer : ITelemetryInitializer
{
    private const string DebugHeaderName = "debug-id";

    public void Initialize(ITelemetry telemetry)
    {
        var dependencyTelemetry = telemetry as DependencyTelemetry;
        if (dependencyTelemetry != null && dependencyTelemetry.TryGetOperationDetail("HttpResponse", out var reponseObject))
        {
            IEnumerable<string> debugData = null;

            var response = reponseObject as HttpResponseMessage;
            if (response?.Headers?.TryGetValues(DebugHeaderName, out debugData) ?? false)
            {
                if (debugData != null)
                {
                    dependencyTelemetry.Properties.Add(DebugHeaderName, string.Join(",", debugData));
                }
            }
        }
    }
}

[christianacca]

I'm trying to use this enhancement but not getting anywhere. Maybe I'm missing some additional configuration?

More information

I've registered a custom telemetry initializer and confirm that it's Initialize method is being called (see code listing). However, the call to dependency.TryGetOperationDetail("HttpResponse", out response) always returns false.

Is there any additional configuration I need to add to my ApplicationInsights.config to enable this enhancement?

Note: I am using version 2.7.2 of the app insight libraries.

Thanks

Code listing

    public class DebugDependencyDataTelemtryInitializer: ITelemetryInitializer
    {
        public void Initialize(ITelemetry telemetry)
        {
            var dependency = telemetry as DependencyTelemetry;
            if (dependency == null) return;

            object response;
            bool found = dependency.TryGetOperationDetail("HttpResponse", out response);
            if (found)
            {
                Console.Out.WriteLine("response = {0}", response);
            }
        }
    }

[pschaeflein]

The issue mentioned by @christianacca is happening to me.

@lmolkova Should this issue be closed? Is there a different issue tracking a but rather than the implementation?

[cijothomas]

@pschaeflein Its possible that Initialize() is called more than once, and in the first call, dependency.TryGetOperationDetail("HttpResponse", out response). this call may not get the response. Initialize() will be called again with the correct response..

Can you check if this is whats happening in your case? We'll investigate more once you share more details, if posible a small repro app.

[pschaeflein]

Yes, Initialize is being called twice, however neither call includes ResponseHeaders. (The rawObjects field always contains only 1 item, the request object.)

I will try to get a repro together. I'm running a bot hosted locally at the moment. (Production will be on Azure App Service.) Below is a list of the NuGet dependencies. Should this environment be supported?