- `account_file` (string) - The JSON file containing your account credentials. If specified, the account file will take precedence over any `googlecompute` builder authentication method. - `project_id` (string) - The project ID where the GCS bucket exists and where the GCE image is stored. - `bucket` (string) - The name of the GCS bucket where the raw disk image will be uploaded. - `image_name` (string) - The unique name of the resulting image.