Hardware checks for Dell R820 Servers through Nagios using SNMP

Maybe I'm weird, but I prefer to monitor my ESXi hosts in a vSphere cluster through the vCenter SNMP interface (coupled with email for certain events). That covers most of what I need. So it's alerting about events versus polling the hardware through something like Nagios.

Can you clarify which specific items you're most interested in monitoring at the host level?

I think vSphere's traps and email alerts can be as granular as you wish...

Nope. VMware has chosen to go the CIM route instead of SNMP, so you can't do exactly what you asked about. The only SNMP support they have implemented is trap-sending, which was very buggy last time I tried it (admittedly a few years ago).

Two good options have already been discussed here (check_esxi_hardware.py, OP5's check-esx-plugin).

As you're probably aware, Nagios Exchange is littered with other people's attempts to solve this, but most of them are outdated and will not work with modern VMware products.

Regarding the problem of having root access, the python plugin used to work without root access past the root level of the CIM tree (e.g., not inherited down to the VMs themselves), but that seems to no longer be the case as of 5.1. You could probably create a special role for Nagios to use (that isn't the administrator role), though.

Judging by the comments you made above (about wanting more-detailed hardware status monitoring), you might be better served by some IPMI checking through the service processor (BMC, LOM, iLO, whatever you want to call it) in that case.

If you're specifically dealing with Dell hardware, you can add the Dell-specific offline bundle (VIB) to enable OpenManage support in ESXi.

In the future, you might be able to use the excellent check_openmanage plugin for this, but it's not currently possible.