http://techdebug.com/blog/2015/09/16/packer-vmware-iso-builder-esxi-without-dhcp/

Config-VMWare.json

{
    "clusterName": "MyCluster",
    "datacenterName": "Melbourne",
    "hostName": "esxihost.localnet",
    "ESXusernameText": "root",
    "ESXpasswordText": "password",
    "user": "packer",
    "password": "password",
    "vm_nameText": "PackerTemplateWin2012R2",
    "vm_networkName": "VM Network",
    "vm_disksize": "71680",
    "vm_diskmode": "thin",
    "datastoreName": "esxihost-1",
    "output_directoryName": "PackerImage",
    "autounattend_file": "autounattend/envA/Autounattend.xml",
    "userdata_file": "scripts/envA/vmware-userdata.ps1"
}