I'm trying to figure out if there's an easy way to convert a tracking pixel request that gets to Nginx into a POST that will go to an upstream with some added body.
for exmaple, if I get a GET request for http://domain.com/track/mail-id.gif
, I'd like to configure Nginx to convert it to a POST that goes to http://upstream/mail-id
with some body (let's say status:opened).
how can it be done?