6f9ed562d5
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 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.
Handlers are loaded with stevedore. To add a new module follow the example
in nova.image.downloads.file.py. The module is required to have two
functions:
get_download_hander():
This must return a child of nova.image.download.TransferBase
get_scheme():
Return the URL scheme that this module handles (ex: 'file')
If additional configuration is needed it can be added by the specific
plug-in (as shown by file_download_module_config included with this
patch submission). Once the module is created it must be added as an
entry point to the python installation. For those included with nova
this can be done by adding the following it setup.cfg:
[entry_points]
nova.download.modules =
file = nova.image.xfers.file
Additionally, as part of the multiple-locations work in Glance meta data
comes back with each location describing it. 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.
blueprint image-multiple-location
Change-Id: I79b863c0075cebaadce5b630f22b81d2959ddbb1
OpenStack Nova README
OpenStack Nova provides a cloud computing fabric controller, supporting a wide variety of virtualization technologies, including KVM, Xen, LXC, VMware, and more. In addition to its native API, it includes compatibility with the commonly encountered Amazon EC2 and S3 APIs.
OpenStack Nova is distributed under the terms of the Apache License, Version 2.0. The full terms and conditions of this license are detailed in the LICENSE file.
Nova primarily consists of a set of Python daemons, though it requires and integrates with a number of native system components for databases, messaging and virtualization capabilities.
To keep updated with new developments in the OpenStack project follow @openstack on Twitter.
To learn how to deploy OpenStack Nova, consult the documentation available online at:
For information about the different compute (hypervisor) drivers supported by Nova, read this page on the wiki:
In the unfortunate event that bugs are discovered, they should be reported to the appropriate bug tracker. If you obtained the software from a 3rd party operating system vendor, it is often wise to use their own bug tracker for reporting problems. In all other cases use the master OpenStack bug tracker, available at:
Developers wishing to work on the OpenStack Nova project should always base their work on the latest Nova code, available from the master GIT repository at:
Developers should also join the discussion on the mailing list, at:
http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack
Any new code must follow the development guidelines detailed in the HACKING.rst file, and pass all unit tests. Further developer focused documentation is available at:
For information on how to contribute to Nova, please see the contents of the CONTRIBUTING.rst file.
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