`json { "builders": [{

"type": "virtualbox-iso",
"guest_os_type": "Ubuntu_64",
"iso_url": "http://releases.ubuntu.com/trusty/ubuntu-14.04.3-server-amd64.iso",
"iso_checksum": "a3b345908a826e262f4ea1afeb357fd09ec0558cf34e6c9112cead4bb55ccdfb",
"iso_checksum_type": "sha256",
"ssh_username": "vagrant",
"ssh_password": "vagrant"

}] } `