Monitoring MySQL servers, we will need to pass through a username and password for MySQL when checking the service availability. Firstly we will create a MySQL user:
We start on the MySQL user and we will log in to the database server and create a new user for Nagios to use. I normally use the local check_mysql plugin so there is no need to let the user login from other servers.
CREATE USER 'nagios'@'localhost' IDENTIFIED BY 'password'
Next check by running the check_mysql plugin
sudo -s -u nagios /usr/lib/nagios/plugins/check_mysql -H localhost -u nagios -p password
Add this to you nrpe definition file and restart nagios-nrpe-server. Add to your Nagios server and away you go!