Check manual page of esx_vsphere_vm.heartbeat
Virtual Machine under ESX: Heartbeat
For a virtual machine running on ESX this check reports the heartbeat
status (queried from vsphere agent)
This check returns:
OK if the guest operating system is responding normally
(vsphere state: green)
WARN on intermittent heartbeat. May be due to guest load.
(vsphere state: yellow)
or if VMware Tools are not installed or not running.
(vsphere state: gray)
CRIT if there is no heartbeat. Guest operating system may have stopped responding.
(vsphere state: red)
See "Monitoring VMWare ESX with Check_MK" in the online documentation
On each VM one check is generated.