I have a fast-cgi application that do some work at http://myapp.com/do?arg=x. The job may take a few minutes. So I want to keep redirecting the users to the same URL (with 307) until the job is done, and serve the results with a 200 OK. I would like to slow done the response rate, so that it takes the client 30s (for example) to receive a 307. Obviously, I don't want to do in the back-end because I need to handle other jobs. It is possible to tell nginx to insert a delay, or rate limit the response for a particular URL?
I've looked at limit_req, but I don't think it can be used to rate limit unique URLS (http://myapp.com/do?arg=x versus http://myapp.com/do?arg=y) but rather unique IP addresses.