NGINX REQUESTS MONITORING

   1) install nginx with http_stub_status module, to check if it is installed with your nginx use below command:
      nginx -V 2>&1 | grep -o with-http_stub_status_module 
      The status module is enabled if you see with-http_stub_status_module as output in the terminal.
      If that command returns no output, you will need to enable the status module. You can use the --with-http_stub_status_module configuration parameter when building NGINX from source.

   2) After verifying the module is enabled or enabling it yourself, you will also need to modify your NGINX configuration to set up a locally accessible URL (e.g., /nginx_status) for the status page:
       server {
       listen       80;
       server_name  localhost;

           location /nginx_status {
           stub_status;
           access_log off;
           allow 192.168.33.1;
           deny all;
           }
      }
    
    you can allow the desired IPs from which you want to access the nginx_status, once the above changes are made, test the nginx configuration using "nginx -t" and reload the nginx process using 
     "nginx -s reload".
  
    3)  Run the python script "nginx_rps.py" from the whitelisted servers, in my case i.e. "192.168.33.1", with "url" "threshold" and "interval" as a command line arguments:
         
         for Ex: python3 nginx_rps.py "http://192.168.33.10/nginx_status" 1000 1

         you will see output like below:

         ----------------------------------------------
         request per second = 8
         request per second = 9

        Please install following modules before running the script as it requires these modules to run:

        (requests, socket, datetime, re)

    4) Now in the other terminsl run the test load on nginx server using below curl command:
        
            for i in {1..10000}; do curl -I "http://192.168.33.10/"; done
    
        As curl is not made for generating concurrent performace load, we can also use "Apache Becnhmark" tool to generate the load:

           ab -kc 3 -n 10000 http://192.168.33.10/

     5) As per the scripts logic it will write in the "Alert" file inside the same directory where the script is placed, if RPS goes beyond 1000 per second. 
        You can increase the "sleep" parameter in the script to collect the RPS "hourly" or any other intervals.        
        
        Below is the sample output from file:
        -----------------------------------------------
        30 Jul 2019 03:25:41	Alert!! 	2554
        30 Jul 2019 03:25:42	Alert!! 	2887
        30 Jul 2019 03:25:43	Alert!! 	2924
        30 Jul 2019 03:26:07	Alert!! 	2867