# Limit\_req\_zone to sleep instead of an error 504 or 404

**URL:** <https://www.ruby-forum.com/t/limit-req-zone-to-sleep-instead-of-an-error-504-or-404/220844>\
**Category:** NGINX\
**Created:** [June 21, 2012, 11:56pm UTC](https://www.ruby-forum.com/t/limit-req-zone-to-sleep-instead-of-an-error-504-or-404/220844 "2012-06-21T23:56:20Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![aris](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/258eb7/32.png) [@aris](https://www.ruby-forum.com/u/aris)\
**Post date:** [June 21, 2012, 11:56pm UTC](https://www.ruby-forum.com/t/limit-req-zone-to-sleep-instead-of-an-error-504-or-404/220844/1 "2012-06-21T23:56:20Z")

</div>

I would like to propose to replace the error code “limit\_req\_zone” sends  
back  
to a user with a simple sleep statement instead.

I am using limit\_req\_zone on some production servers to limit the amount  
of  
downloads each ip can execute over time. “fastcgi\_param” is used to  
execute  
an external fastcgi script to deliver the data to the client from a  
back end cluster.

Users are accessing the nginx front end using automated scripts and  
accessing  
data without problem as long as they stay below our limit\_req\_zone value  
of 200  
requests per 60 seconds.

When they hit the limit\_req\_zone value the clients are being limited  
correctly  
and being delayed until their requests per minute goes below the  
specified value.

My issue is when a user hits the limit an error 503 (for local files) or  
an  
error 404 (for fastcgi scripts) is sent back to the user. The error  
503 is documented  
on the nginx site and expected as “service unavailable”. The error 404  
for fastcgi is  
not mentioned and took some trial and error to figure out why it was  
in the logs.

For those interested, here is a sanitized copy of the error.log. The  
client does a  
head request and has exceeded 200 req/min by 0.094 req/min. At this  
point I would  
imagine a 503 would be sent back to the client. Instead, the second  
error line  
shows nginx trying to look for the URI on the local file system. The  
problem is  
file.bz2 is the file the fastcgi script would serve out and is _not_ a  
local file in  
htdocs. The script is really located at /disk/web/cgi/getter .

Here is the nginx.conf for getting a file through the fast cgi method:

limit\_req\_zone $binary\_remote\_addr zone=one:10m rate=30r/m;

root /disk/web/htdocs;  
limit\_req zone=one burst=100 nodelay;

```
 location ~* ^/script/[\w.-]+$ {
         gzip off;
         fastcgi_max_temp_file_size 0;
         fastcgi_split_path_info ^((?U).+script)(/?.+)$;
         fastcgi_intercept_errors on; #<--------
         fastcgi_pass unix:/var/run/fcgiwrap.socket;
         include /usr/local/nginx/conf/fastcgi_params;
         fastcgi_param DOCUMENT_ROOT $document_root;
         fastcgi_param PATH_INFO $fastcgi_path_info;
         fastcgi_param SCRIPT_NAME /cgi/getter;
         fastcgi_param SCRIPT_FILENAME /disk/web/cgi/getter;
 }

```

2012/06/21 15:04:43 [error] 19685#0: \*11354 limiting requests, excess:  
200.094 by zone “one”, client: 128.x.x.x, server: ourserver, request:  
“HEAD /cgi/getter/file.bz2 HTTP/1.1”, host: “ourserver”

2012/06/21 15:04:53 [error] 19685#0: \*11354 open()  
“/disk/web/htdocs/cgi/getter/file.bz2” failed (2: No such file or  
directory), client: 128.x.x.x, server: ourserver, request: “HEAD  
/cgi/getter/file.bz2 HTTP/1.1”, host: “ourserver”

Sending back an error 404 (File not found) for a file that does exist  
through  
an external script causes a lot of confusion to the user. This is may be  
just  
a unforeseen coding issue though.

I propose a better situation is to limit users, but when they hit the  
predefined  
limit\_req\_zone value have the options to sleep for a few seconds, check  
if  
they are under the request limit and then complete the original request.  
A  
simple delay in responding to the client, similar to Maxim’s  
ngx\_http\_delay,  
would be invaluable.

Perhaps adding an option to the limit\_req\_zone directive would be good.

limit\_req\_zone $binary\_remote\_addr zone=one:10m rate=30r/m;  
error=2sec  
(or if you want to send an error)  
limit\_req\_zone $binary\_remote\_addr zone=one:10m rate=30r/m;  
error=504

Another idea is for limit\_req\_zone to trigger an unused error code  
(12345) and  
allow the nginx config to trap it. This way the admin could delay the  
response  
or even send back an error.

error\_page 12345 @abuse  
location /abuse {  
delay 5s;  
}

I am going to look in the nginx source for where nginx is sending the  
504 for  
limit\_req\_zone from. If anyone has any other ideas I would be happy to  
hear  
them and very open to suggestions.

---

<div class="post-metadata">

**Author:** ![CM\_Fields](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/439d5e/32.png) [@CM\_Fields](https://www.ruby-forum.com/u/CM_Fields)\
**Post date:** [June 22, 2012, 2:55am UTC](https://www.ruby-forum.com/t/limit-req-zone-to-sleep-instead-of-an-error-504-or-404/220844/2 "2012-06-22T02:55:47Z")

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Please disregard my previous email.

The issue was on my side when I setup error\_page with a delay, but  
then forgot to setup the proper error response.