I'd like some way to connect nagios, so it sees the status of the Virtual Center, i.e. if the infrastructure client shows an alarm, it is shown in nagios.
Not nessecary to show the errormessage, just nagios showing "Something wrong", so I can look at the Infrastructure client to see what's wrong.
Otherwise an error can be unnoticed for days, if nothing seems to be out of order, as I'm not looking at IC, while Nagios is running all the time (or actually a nagios-popup)
I was looking for a good vCenter or even just ESX(i) check for Nagios a while back, and I didn't find anything. I ended up writing one-off scripts to cover the need, and I'm going to go back and improve them when I get a chance.
There is this: http://exchange.nagios.org/directory/Addons/Configuration/Configuration-Wizards/VMware-ESX--2F-vSphere--2F-vCenter-Monitoring-Wizard/details but I haven't tried it, as it's only compatible the commercial version of Nagios, Nagios XI.
If you can script in perl, the VMware SDK is available here: http://www.vmware.com/support/developer/viperltoolkit/
It should contain all of the functions necessary to do what you want (and then some).
Take a look at Netway's VMWare Plugin for Nagios. I don't think you can check VirtualCenter with it, but the ESX hosts and Guests work
You can find more about it here: http://www.netways.de/en/de/produkte/nagios_plugins/vmware_esx/
We use check_esx3 in conjunction with ESX server and standard nagios on Centos - it works well.
Since new versions of vmware old systems doesnt work (SNMP or running local commands inside ESX). There is no way to make it work with new API/Versions of Vmware, other monitoring systems (Zabbix, Pandora FMS, Open NMS) have the same problem, and the API is a hell :( I don't see any free plugin for ESX monitoring yet :(