How-to enable Nginx status monitoring

Owned by Anastasios Thomaidis
Last updated: Oct 04, 2024 by Matthew Hierholzer
This check parses the information provided by the NGINX stub status module. If you have enabled that module, then the URL /nginx_status shows interesting information about the inner state of the web server when accessed from localhost. The agent plugin nginx_status fetches this information and processes it.

LAST TESTED ON CHECKMK 2.2.0P1

Table of Contents

Step-by-step guide

After installing and configuring Nginx, you can follow these steps to monitor Nginx status.

  1. Nginx stub status module

    Make sure that the server process is configured with the stub status module. Use the command:

    root@linux:~# nginx -V 2>&1 | grep -o with-http_stub_status_module   
with-http_stub_status_module

    If the stub status module is not installed, you can follow this guide for the installation: https://www.tecmint.com/enable-nginx-status-page/

  2. Add a new server block configuration inside /etc/nginx/sites-enabled/default

    /etc/nginx/sites-enabled/default
    server {
        listen 8081;
        listen [::]:8081;

        server_name _;

        root /var/www/html;
        index index.html;

        location /nginx_status
{
                stub_status on;
                access_log off;
                allow 127.0.0.1;
                deny all;

        }
}

    .

  3. Restart nginx service

    root@linux:~# systemctl restart nginx

    .

  4. Now the URL 127.0.0.1:8081/nginx_status should be available

    root@linux:~# wget -qO - http://127.0.0.1:8081/nginx_status
Active connections: 1 
server accepts handled requests
 1 1 1 
Reading: 0 Writing: 1 Waiting: 0

    .

  5. Configure nginx_status

    • Manually
      You must install the agent plugin nginx_status into your agent's plugins directory (usually /usr/lib/check_mk_agent/plugins). The plugin tries to autodetect all running NGINX servers. If that fails, you must create the configuration file /etc/check_mk/nginx_status.cfg. Here is one example:

      servers = [{'address': '127.0.0.1',
  'page': 'nginx_status',
  'port': 8081,
  'protocol': 'http'}]

    • via Bakery
      Setup → Agents → Windows, Linux, Solaris... → Agent rules →NGINX webservers (Linux)

      • Autodetect instances expect HTTPS on the following ports: nginx_status will try to autodetect all running NGINX servers.
        Screenshot of New rule for Nginx webserver. Autodetect instances, expect HTTPS on the following ports enabled. Port 443 selected.

      • Specific list of instances: You can specify NGINX instances
        Screenshot of New rule for Nginx webserver. Specific list of instances enabled. Protocol set to HTTP. IP address used in this example is 127.0.0.1. TCP port number set to 8081. URI set to nginx_status.

  6. Test the plugin

Now you can execute the plugin manually and see if it works:

MK_CONFDIR=/etc/check_mk /usr/lib/check_mk_agent/plugins/nginx_status 

<<<nginx_status>>>
127.0.0.1 8081 Active connections: 1 
127.0.0.1 8081 server accepts handled requests
127.0.0.1 8081  380 380 380 
127.0.0.1 8081 Reading: 0 Writing: 1 Waiting: 0


Check_MK will create one service for each web server.
Screenshot of Undecided services, currently not monitored 1. Check reports pending.

Debugging

Port Checking

root@linux:~# netstat -tulpen |grep 8081
tcp        0      0 0.0.0.0:8081            0.0.0.0:*               LISTEN      0          43044      1353/nginx: master  
tcp6       0      0 :::8081                 :::*                    LISTEN      0          43045      1353/nginx: master


Nginx Service

root@linux:~# systemctl status nginx

Stub status module

root@linux:~# nginx -V 2>&1 | grep -o with-http_stub_status_module   
with-http_stub_status_module


Checking the status page

root@linux:~# wget -qO - http://127.0.0.1:8081/nginx_status
Active connections: 1 
server accepts handled requests
 398 398 398 
Reading: 0 Writing: 1 Waiting: 0


We also have detailed documentation about nginx_status: https://checkmk.com/cms_check_nginx_status.html.

Do you want to learn more about monitoring web servers? Check out our blog page: https://checkmk.com/blog/how-to-monitor-web-server.