Monitoring Nginx Connections

The Nginx web server comes with a bundled module “HttpStubStatusModule”. By enabling this module we will get some insight of our nginx connections. This module provides the following information.

Active Connections

Enable Module
To get connection stats, we need to enable the status module on nginx VirtualHost file by adding below localtion block.

location /nginx_status {
        # Turn on stats
        stub_status on;
        allow 127.0.0.1;
        deny all;
}

Replace 127.0.0.1 with the IP from which you wants to access /nginx_status

$ sudo service nginx reload 

$ curl localhost/nginx_status 

Active connections: 32 
server accepts handled requests
48932 48932 2594381 
Reading: 0 Writing: 2 Waiting: 30

Let’s break down the above parts.

1. Active Connections (Number of Active Connection):

This will give all open connections. This doesn’t mean number of users on site.

2. Server accepts handled requests:

We have three values for this.

First Column: 48392 ( Total Accepted Connection by Web Server )
Second Column: 48932 ( Total Connections handled by Web Server )
Third Column : 2594381 ( Number of handled requests )

If we divide third column by second column, we’ll get the number of requests / second

Hence,

Number of Requests/Second = 2595381 / 48392 = 53.63

requests is being served per second by nginx.

You can also use the below script and execute it as a cron and check Connection Status on a timely basis.

#!/bin/bash

numberOfActiveConnections=""
numberOfTotalAcceptedConnections=""
numberOfTotalhandledConnections=""

#Number of Requests / Second
numberOfRequestsPerSecond=""

nginxPath='nginx_status'

ApplicationURL=' List of IPAddress/DomainName separated by Space '

echo $ApplicationURL

for URL in ${ApplicationURL[@]};do
    
    
    file="$URL"
    echo "Getting Nginx Status Page of $URL"
    
    curl -s $URL/$nginxPath -o $file
    
    numberOfActiveConnections=$(cat $file  | awk '/Active /' | awk '{print $3}')
    echo "$file : Active Connection $numberOfActiveConnections"
    
    
    numberOfTotalAcceptedConnections=$(cat $file | grep -A 1 server | tail -1 | awk '{print $1}')
    echo "$file : Total Accepted Connection $numberOfTotalAcceptedConnections"
    
    numberOfTotalhandledConnections=$(cat $file | grep -A 1 server | tail -1 | awk '{print $2}')
    echo "$file : Total Handled Connection $numberOfTotalhandledConnections"
    
    echo "Number of Accepted and Handle remains same most of the time."
    totalRequests=$(cat $file | grep -A 1 server | tail -1 | awk '{print $3}')
    
    numberOfRequestsPerSecond=$(echo 'scale=2;'$totalRequests/$numberOfTotalAcceptedConnections | bc -l)
    echo "Currently Server is serving $numberOfRequestsPerSecond / second."
    
    echo "---------------------------------------------------------------------------------------------------------------"
    
done

Output will be like:

Getting Nginx Status Page of Application URL
Application URL : Active Connection 39
Application URL : Total Accepted Connection 62032
Application URL : Total Handled Connection 59739
Number of Accepted and Handle remains same most of the time.
Currently Server is serving 43.02 / second.

Leave a comment if you have any questions regarding this article.