Throttle requests with limit_req rate based on header from response to auth subrequest

jarstewa nginx-forum at
Fri Aug 31 00:13:33 UTC 2018

Hmm, I notice this from the map documentation: 

> Since variables are evaluated only when they are used, the mere
declaration even of a large number of “map” variables does not add any extra
costs to request processing.

Here is what I suspect: 

1) The limit_req directive is being processed before the auth subrequest
2) Therefore, when the limit_req is present, the mapped variables are empty
since the header from the auth request is not present.  But when limit_req
is removed, the mapped variables are evaluated by the access_log, which
happens after the auth subrequest has been made.

Can anyone kindly confirm or reject this theory? 

Thanks again,

Posted at Nginx Forum:,281034,281057#msg-281057

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