ProvisionServer can be used as CLI or Server.

Example of input file:
{
  "id": {
    "value": "provision_id"
  },
  "system_image": {
    "version": "R99-99999.99.99",
    "system_image_path": {
      "host_type": "GS",
      "path": "gs:/special_path_to_the_image"
    }
  },
  "packages": [
    {
      "package_path": {
        "host_type": "GS",
        "path": "gs:/special_path_to_the_image"
      },
      "portage_package": {
        "package_name": "chromeos-lacros",
        "category": "chromeos-base",
        "version": "99.9.9999.r9"
      }
    },
    {
      "package_path": {
        "host_type": "GS",
        "path": "gs:/special_path_to_the_image"
      },
      "portage_package": {
        "package_name": "chromeos-chrome",
        "category": "chromeos-base",
        "version": "99.9.9999.r9"
      }
    }
  ],
  "firmware": {},
  "prevent_reboot": false
}