---
issues:
  - |
    When generating Libvirt XML to attach network interfaces for the `tap`,
    `ivs`, `iovisor`, `midonet`, and `vrouter` virtual interface types Nova
    previously generated an empty path attribute to the script element
    (`<script path=''/>`) of the interface.

    As of Libvirt 1.3.3 (`commit`_) and later Libvirt no longer accepts an
    empty path attribute to the script element of the interface. Notably this
    includes Libvirt 2.0.0 as provided with RHEL 7.3 and CentOS 7.3-1611. The
    creation of virtual machines with offending interface definitions on a host
    with Libvirt 1.3.3 or later will result in an error "libvirtError: Cannot
    find '' in path: No such file or directory".

    Additionally, where virtual machines already exist that were created using
    earlier versions of Libvirt interactions with these virtual machines via
    Nova or other utilities (e.g. `virsh`) may result in similar errors.

    To mitigate this issue Nova no longer generates an empty path attribute
    to the script element when defining an interface. This resolves the issue
    with regards to virtual machine creation. To resolve the issue with regards
    to existing virtual machines a change to Libvirt is required, this is being
    tracked in `Bugzilla 1412834`_

    .. _commit: https://libvirt.org/git/?p=libvirt.git;a=commit;h=9c17d665fdc5f0ab74500a14c30627014c11b2c0
    .. _Bugzilla 1412834: https://bugzilla.redhat.com/show_bug.cgi?id=1412834