In this recipe, we'll learn how Nagios Core can be used to monitor the status of a database server. We'll demonstrate with the popular MySQL as an example, using the check_mysql plugin, and we'll discuss running an actual test query and specifying a similar check for PostgreSQL in the There's more… section.
You should have a Nagios Core 4.0 or newer server with at least one host configured already. We'll use the example of delphi.example.net, a host defined in its own file. You should also understand the basics of how hosts and services relate, which is covered in the recipes in Chapter 1, Understanding Hosts, Services, and Contacts.
For a check on a remote host to work from the monitoring server, the database server will need to be listening on an appropriate network interface. It's also necessary to make sure that an appropriate database user account exists with which the check_mysql plugin may authenticate. It's a good idea to make this into a dedicated...
