Another use for Variables is within the context of 'Multiple Service Checks'. For example, if there is a Service Check that monitors the capacity of a hard drive it may take the following format:
check_disk 'a %DISK% By having the %DISK% variable, this Service Check requires the Variable %DISK% to be added to the Host and populated with the value field of %DISK% containing the hard disk to be monitored. If the value was set to 'C', the Service Check, when executed, would read:
check_disk 'a C
This is great if we just have one disk, but what if we have multiple? A D:/ drive? An F:/ drive? That would require administrators to create three separate Service Checks:
check_disk -a C check_disk -a D check_disk -a F
This defeats the purpose of Variables. Therefore, Opsview Monitor created the concept of 'Multiple Service Checks'. This allows an administrator to create the Service Check below:
check_disk 'a %DISK%
But unlike before, there is an option called 'Multiple Service Checks:'. Within this dropdown box, an administrator can select a Variable, i.e. %DISK%. By selecting %DISK%, this tells Opsview Monitor to create a new Service Check for every %DISK% variable added.
This means, that for every %DISK% variable added to the Host ' Opsview Monitor will create a new Service Check. This means the administrator needs to only create and add one Service Check, 'check_disk 'a %DISK%'. The administrator then simply adds three variables of the DISK type, with the values C, D and F respectively.
On 'submit changes' and a reload, the one Service Check will create three copies ' one per variable.
In Opsview Monitor, this looks like the screen below:
This next step assumes the Service Check is already added to the Host; either via the Hosts' 'Service Check' tab or via a Host template.
Once reloaded, the one Service Check will be cloned three times, one per variable, as shown below: