connection_type=vmwareapi

Hi,

On your nova compute host (most likely a VM on the ESXi host itself) you have to add this lines on nova.conf file:

--vmwareapi_host_ip=10.10.10.25
--vmwareapi_host_username=root
--vmwareapi_host_password=root
--vmwareapi_wsdl_loc=http://10.10.10.123:8080/wsdl/vim25/vimService.wsdl

The first in obviously the host in which your Hypervisor is installed, then at the last line you have to specify the location of VMWare wsdl.
Download it from: http://www.vmware.com/support/developer/vc-sdk/