openstack/glance
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Release note for 'compressed' container format

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Change-Id: I2f28190e5a9af62d6073ccf47fb9338eca026567
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Brian Rosmaita 2019-08-27 09:22:50 -04:00
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---
features:
- |
The identifier ``compressed`` has been added to the list of supported
container formats. The intent is that this format identifier will be used
for any compressed file archive format (for example, gzip or rar) that is
not otherwise covered by the existing container format identifiers.
As with all container formats, Glance does not verify that the data payload
of an image is actually in that format. Further, you should not expect
other OpenStack services to be able to handle arbitrary compressed file
formats. Consult the documentation of any services that will consume your
image for details.
upgrade:
- |
The identifier ``compressed`` has been added to the list of supported
container formats. The intent is that this format identifier will be used
for any compressed file archive format (for example, gzip or rar) that is
not otherwise covered by the existing container format identifiers.
The ``compressed`` container format was added in support of the Cinder
(Block Storage Service) feature `Leverage compression accelerator
<http://specs.openstack.org/openstack/cinder-specs/specs/train/leverage-compression-accelerator.html>`_.
You may expect that Cinder will be able to consume any image in
``compressed`` container format *that Cinder has created*. You should
not expect, however, for other services to be able to consume such an image
at the present time. Further, you should not expect Cinder to be able
to successfully use an image in ``compressed`` format that it has not
created itself.
issues:
- |
The introduction of the ``compressed`` container format in this release
gives us the opportunity to remind you that Glance does not verify that
the ``container_format`` image property is accurate for *any* container
format. It is the responsibility of the image consumer to verify the
image data payload format and take appropriate action in the case of a
misdescribed image.
- |
The intent of the ``compressed`` container format identifier introduced
in this release is that it will be used for any compressed file archive
format (for example, gzip or rar) that is not otherwise covered by the
existing container format identifiers.
The exact format of the compressed file is unspecified. It is the
responsibility of the consuming service to analyze the data payload and
determine the compression format. A particular OpenStack service may only
support specific formats. Thus, even if a service does support the
``compressed`` container format, this does not imply that the service can
handle arbitrary compression formats. Consult the documentation for the
service that will consume your image for details.
- |
As of this release, the only service using the ``compressed`` container
format is Cinder (Block Storage Service), when Cinder is configured to use
compression when uploading a volume-image to Glance. While you may expect
that Cinder will be able to consume any image in ``compressed`` container
format *that Cinder has created*, you should not expect Cinder to be able
to successfully use an image in ``compressed`` format that it has not
created itself. Consult the `Cinder documentation
<https://docs.openstack.org/cinder/latest>`_
for more information.