1. Define new command in /usr/local/nagios/etc/commands/
define command {
command_name check_my_service
command_line $USER1$/check_http -H example.com -u "http://example.com/health/someapi/" -a <username>:<password>
}
Above is example for checking http with authorization (see check_http –help for options)
2. Add a check with the name of the command that you defined above to /usr/local/nagios/etc/services/
define service{
use generic-service
service_description Check for my new service
check_command check_my_service
host_name localhost
}