Azure SDK ExtractContext exmaples

extract_activity_context.cs

public static class MessagingExtensions
{
    // potential addition to event hubs SDK. service bus is similar
    // The only concern is availability of ActivityContext prior to .NET 5
    // there is a potential to update DiagnosticSource, but it's problematic because of 
    // version conflict: binding redirects on .NET Fx and version conflicts with Functions load contexts
    public static ActivityContext ExtractTraceContext(this EventData @event)
    {
        if (@event.Properties.TryGetValue("Diagnostic-Id", out var tp) && tp is string traceparent)
        {
            ActivityContext.TryParse(traceparent, null, out var context);
            return context;
        }

        return default(ActivityContext);
    }
    
    // event grid
    public static ActivityContext ExtractTraceContext(this CloudEvent @event)
    {
        if (@event.ExtensionAttributes.TryGetValue("traceparent", out var tp) && tp is string traceparent)
        {
            string tracestateStr = null;
            if (@event.ExtensionAttributes.TryGetValue("tracestate", out var ts) && ts is string tracestate)
            {
                tracestateStr = tracestate;
            }

            ActivityContext.TryParse(traceparent, tracestateStr, out var context);

            return context;
        }

        return default(ActivityContext);
    }

    // another approach for old DiagnositcSource (prior to .NET 5)
    public static ValueTuple<string, string> ExtractTraceContext2(this CloudEvent @event)
    {
        if (@event.ExtensionAttributes.TryGetValue("traceparent", out var tp) && tp is string traceparent)
        {
            string tracestateStr = null;
            if (@event.ExtensionAttributes.TryGetValue("tracestate", out var ts) && ts is string tracestate)
            {
                tracestateStr = tracestate;
            }

            return (traceparent, tracestateStr);
        }

        return (null, null);
    }
}

// usage, assumes DiagnosticSource 5+ usage 
var cloudEvent = new CloudEvent("source", "type", new object());

// example 1
using (var sendActivity = source.StartActivity("Process CloudEvent", ActivityKind.Consumer, cloudEvent.ExtractTraceContext()))
{
    await publisherClient.SendEventAsync(cloudEvent);
}

// example 2
var (traceparent, tracestate) = cloudEvent.ExtractTraceContext2();
ActivityContext.TryParse(traceparent, tracestate, out var activityContext);
using (var sendActivity = source.StartActivity("Process CloudEvent", ActivityKind.Consumer, activityContext))
{
    await publisherClient.SendEventAsync(cloudEvent);
}