Nginx headers to be set at the time of request processing

[CeeGeeDev]

To be clear, this is for a custom http module we wrote. We want it to know
about request headers that we set in the nginx.conf (for proxy_pass etc).
But it doesn't seem like the custom module receives the modified request
headers. Is there any way to both a) set a request header for proxy_pass but
also b) have custom http module code living inside the same nginx also
process the request that has these alterations to the set of request
headers?

Thanks

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,271147,271149#msg-271149