Comment 8 for bug 1196924

Reviewed: https://review.openstack.org/68942
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=c07ed15415c0ec3c5862f437f440632eff1e94df
Submitter: Jenkins
Branch: master

commit c07ed15415c0ec3c5862f437f440632eff1e94df
Author: Phil Day <email address hidden>
Date: Fri Jan 24 15:43:20 2014 +0000

    Power off commands should give guests a chance to shutdown

    Currently in libvirt operations which power off an instance such as stop,
    shelve, rescue, and resize simply destroy the underlying VM. Some
    GuestOS's do not react well to this type of power failure, and so it would
    be better if these operations followed the same approach as soft_reboot
    and give the guest as chance to shutdown gracefully.

    The shutdown behavior is defined by two values:

    - shutdown_timeout defines the overall period a Guest is allowed to
    complete it's shutdown. The default valus is set via nova.conf and can be
    overridden on a per image basis by image metadata allowing different types
    of guest OS to specify how long they need to shutdown cleanly.

    - shutdown_retry_interval defines how frequently within that period
    the Guest will be signaled to shutdown. This is a protection against
    guests that may not be ready to process the shutdown signal when it
    is first issued. (e.g. still booting). This is defined as a constant.

    This is one of a set of changes that will eventually expose the choice
    of whether to give the GuestOS a chance to shutdown via the API.

    This change implements the libvirt changes to power_off() and adds
    a clean shutdown to compute.manager.stop().

    Subsequent patches will:
    - Add clean shutdown to Shelve
    - Add clean shutdown to Rescue
    - Convert soft_reboot to use the same approach
    - Expose clean shutdown via rpcapi
    - Expose clean shutdown via API

    Partially-Implements: blueprint user-defined-shutdown
    Closes-Bug: #1196924
    DocImpact

    Change-Id: I432b0b0c09db82797f28deb5617f02ee45a4278c