packer + ansibleでUNREACHABLE!

packerからansibleでprovisioningするときに、こういうエラーでた。

    googlecompute: PLAY [all] *********************************************************************
    googlecompute:
    googlecompute: TASK [Gathering Facts] *********************************************************
==> googlecompute: failed to handshake
    googlecompute: fatal: [default]: UNREACHABLE! => {"changed": false, "msg": "Failed to connect to the host via ssh: Warning: Permanently added '[127.0.0.1]:53116' (RSA) to the list of known hosts.\r\nReceived disconnect from 127.0.0.1 port 53116:2: too many authentication failures\r\nDisconnected from 127.0.0.1 port 53116", "unreachable": true}
    googlecompute:      to retry, use: --limit @/xxx
    googlecompute:

色々探して、ここにたどり着く。
https://github.com/hashicorp/packer/issues/5329

  "provisioners": [
    {
      "type": "ansible",
      "playbook_file": "../ansible/master-image-playbook.yml",
      "extra_arguments": [
        "--ssh-extra-args",
        "-o IdentitiesOnly=yes"
      ]
    }
  ]

解決。