exposing request start time as a variable to use in a custom header

[JD Harrington]

Hi,

I'm using New Relic RPM for performance profiling and they have an
optional metric for time spent in request queueing. In order to
compute this metric, they require that the frontend server add an
X-QUEUE-START request header with a timestamp in microseconds before
handing the request off to the application. There are a couple of
patches floating around that add this ability to various versions of
nginx.

I'm wondering if this or something similar might be considered for
inclusion in a future official release of nginx.

Details about the New Relic feature:
https://newrelic.com/docs/features/tracking-front-end-time

The currently available patches:
https://gist.github.com/318681

Thanks!

JD