Nginx Rate limiting for HTTPS requests

[rickGsp]

>>- Make sure the $host variable you use for the limiting is not 
>>empty and not changed between requests created by your testing 
>>tool. Try logging the variable to see if it changes or not. 
>>Alternatively, replace it with a static string to see if it helps.

Checked. $host variable is set for all the requests.

>>- Make sure there are no unrelated requests in the log. In 
>>particular, you may want to use different logs in the server{} 
>>block you are limiting and in the http{} block.

Checked. There are no unrelated requests in the log.

>>- Try another tool to see if you are able to reproduce the same 
>>effect. Something simple like "ab" or "http_load" might be a 
>>good choice.

Checked with "ab" with as following (concurrency 700 requests);
ab -n 20000 -c 700 https://9.0.0.10:443/test.html

Here is the piece of output. As per the report test ran for approx. 50
seconds and 20000-14622 = 5278 requests returned with success. This is as
expected as per rate limiting at 100r/s for 50 seconds test. Notice that
Mean requests processed per second is 396.

Concurrency Level:      700
Time taken for tests:   50.437 seconds
Complete requests:      20000
Failed requests:        14722
Requests per second:    396.53 [#/sec] (mean)

Access log report for this test as per the following command seems to be
fine: grep ' 200 ' /path/to/log | awk '{print $4}' | uniq -c
   111 [22/May/2018:15:35:04
    101 [22/May/2018:15:35:05
     95 [22/May/2018:15:35:06
     98 [22/May/2018:15:35:07
     97 [22/May/2018:15:35:08
    106 [22/May/2018:15:35:09
     95 [22/May/2018:15:35:10
     99 [22/May/2018:15:35:11
    104 [22/May/2018:15:35:12
    106 [22/May/2018:15:35:13


In another test, I ran two instances of "ab" in parallel with same
configuration and following is the output.This is again approx. 50 seconds
test. By combining both the reports (20000+20000) - (9344+10239) = 20417
requests returned with success. This is four times of expected 5000
requests/sec rate. I would like to understand this behaviour. I guess this
is happening in my tests as well. In my case I just keep pushing requests
without waiting for response.

First instance:
Concurrency Level:      700
Time taken for tests:   46.944 seconds
Complete requests:      20000
Failed requests:        9344
Requests per second:    426.04 [#/sec] (mean)

Second Instance:
Concurrency Level:      700
Time taken for tests:   53.344 seconds
Complete requests:      20000
Failed requests:        10239
Requests per second:    374.92 [#/sec] (mean)


Access log report for this test as per the following command does not seem
to be fine: grep ' 200 ' /path/to/log | awk '{print $4}' | uniq -c
    180 [22/May/2018:15:52:59
    276 [22/May/2018:15:53:00
     33 [22/May/2018:15:53:01
     20 [22/May/2018:15:53:00
     70 [22/May/2018:15:53:01
      1 [22/May/2018:15:53:00
    181 [22/May/2018:15:53:01
     16 [22/May/2018:15:53:02
      2 [22/May/2018:15:53:01
     99 [22/May/2018:15:53:02
      1 [22/May/2018:15:53:01
    177 [22/May/2018:15:53:02
    329 [22/May/2018:15:53:03
      8 [22/May/2018:15:53:02

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,279802,279908#msg-279908