Nginx "auth_request" like option for rate limiting - nginx

Question

In Nginx I want to send a pre-request to another endpoint which checks for rate limiting violations. Basically exactly what auth_request does, but where auth_request only accepts authentication status codes (200, 401, 403), I want it to only allow rate limiting codes (200 or 429).
Is there a more general version of auth_request which could be used for this?
For now we're using auth_request, but the downside is it turns 429 status codes into 500s.
Thanks!

Answer 1

Below config works for me and returns a 429 instead of 500
events {
worker_connections 1024;
}
http {
server {
listen 80;
location /api {
auth_request /rate_limit;
error_page 500 = #rate_limit_error;
echo "You were allowed to access the API";
}
location #rate_limit_error {
return 429 "Limit has been exceeded\n";
}
location = /rate_limit {
internal;
return 400 "Access is not allowed";
}
}
}
The test shows the correct response
$ curl -v localhost/api?count=2
* Trying ::1...
* Connected to localhost (::1) port 80 (#0)
> GET /api?count=2 HTTP/1.1
> Host: localhost
> User-Agent: curl/7.47.0
> Accept: */*
>
< HTTP/1.1 429
< Server: openresty/1.11.2.2
< Date: Sat, 30 Sep 2017 18:50:56 GMT
< Content-Type: text/plain
< Content-Length: 24
< Connection: close
<
Limit has been exceeded
* Closing connection 0
If you don't want to return a message or something else. You can also use error_page 500 = 429;