Trying to limit requests in Nginx per URI

Question

I find myself needing to limit the number of requests a particular IP can send for a particular URI (e.g. www.foo.com/somewhere/special) while leaving the rest of the site unregulated.

How would I configure that using the HttpLimitReqModule built into Nginx?

Answer 1

Here's how it is done on one of my sites. First, we use geo module to define a variable that be used to identify limited addresses:

geo $slow {
    default 0;
    include /etc/nginx/conf.d/slowlist;
}

The slowlist file is like this:

192.168.0.0/24  1;
192.168.10.0/24  1;

and so on (IP addresses are just examples, of course). Then we define speed limits:

limit_req_zone $binary_remote_addr zone=fast:1m rate=1000r/s;
limit_req_zone $binary_remote_addr zone=slow:10m rate=20r/m;

Now we have to assign req_zones to every IP address. Inside the necessary location, we check the variable $slow, and if equals 1, we redirect to location @slow (using fictitious error 555):

recursive_error_pages on;
error_page 555 = @slow;
if ($slow = 1) {
    return 555;
}
limit_req zone=fast burst=10000 nodelay;

Then normal rules follow, including root, index, fastcgi*, whatever. Limit zone 'fast' will be used here. And, finally, we define location @slow, where limit zone 'slow' will be used:

location @slow {
    limit_req zone=slow burst=5 nodelay;

Then normal rules follow, including root, index, fastcgi*, whatever.

So, usual requests are processed in the normal location, but all others are redirected to the location @slow.

Answer 2

You need to add a

location /somewhere/special {
...
}

where you configure your limits with HttpLimitReqModule or HttpLimitZoneModule modules.