At InVision, David Bainbridge and I have been working hard to figure out why some users are getting randomly logged-out of one of our client-side applications. Part of what makes this issue so challenging to debug is that there are many services that touch requests coming out of this application. And, even though we are using request tracing headers in our distributed system, we are struggling to connect the dots as those requests pass-through Amazon's load balancers. Yesterday, however, David discovered that Amazon's load balancers will record (and modify) the HTTP header, X-Amzn-Trace-Id, within their request logs. I think this may really help us!