Comment 1 for bug 1648840

Reviewed: https://review.openstack.org/408806
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=5e7f765266e0b94807e019b645c8be89770e7428
Submitter: Jenkins
Branch: master

commit 5e7f765266e0b94807e019b645c8be89770e7428
Author: Dan Smith <email address hidden>
Date: Thu Dec 8 12:25:37 2016 -0800

    Cleanup after any failed libvirt spawn

    When we go to spawn a libvirt domain, we catch a few types of exceptions
    and perform cleanup before failing the operation. For some reason, we
    don't do this universally, which means that we leave things like network
    devices laying around (from plug_vifs()). If a delete comes later, it
    should clean those things up. However, if a subsequent failure prevents
    that, and especially if we do a local delete at the API, we'll leak those
    interfaces.

    As seen in at least one real-world situation, this can cause us to leak
    interfaces until we have tens of thousands of them on the system, which
    then causes secondary failures.

    Since we run the cleanup() routine for certain failures, it certainly
    seems appropriate to run it always and not leave residue until a
    successful delete is performed.

    Closes-Bug: #1648840
    Change-Id: Iab5afdf1b5b8d107ea0e5895c24d50712e7dc7b1