Open Stack

Hi, I'd like you to take a look at this patch for potential
DocImpact.
https://review.openstack.org/37817

Log:
commit 4818e7d661054560ffad503b3dc61929d233b8fc
Author: John Bresnahan <jbresnah at redhat.com>
Date:   Thu Jul 18 10:39:33 2013 -1000

    Add plug-in modules for direct downloads of glance locations.
    
    Glance can expose direct URL locations to its clients.  In current
    versions of nova the only URL that can be accessed directly is file://.
    This patch adds a notion of download plug-ins.  With this new download
    protocol modules can be added to without disruption to the rest of the
    code base.  Based on the scheme of the URL returned from Glance a
    plug-in will be loaded and used to download the data directly, instead
    of first routing it through Glance.  If anything fails in the process
    the image will be downloaded by way of Glance.
    
    To add a new download handler one must create a file with a JSON
    document in it.  The document must have the following:
    {
        'scheme': <a string representing the scheme this plug-in handles>
                  ex: 'file',
        'module': <a python module path to the download handler class>
    
        # the remaining entries are defined by the plug-ins specific needs
    }
    The path to this file is then added to the new option: download_modules.
    
    Additionally, as part of the multiple-locations work in Glance meta data
    comes back with each locations describing that location.  As an example,
    this is needed for direct access to file URLs.  Nova cannot assume that
    every file URL is accessible on its mounted file systems, nor can it
    assume that the mount points are the same.  This patch solves that
    problem for direct access to files.
    
    docImpact
    blueprint: image-multiple-location
    
    Change-Id: I79b863c0075cebaadce5b630f22b81d2959ddbb1

Automatically generated bug (please review):
https://bugs.launchpad.net/bugs/1202891