openstack/glance
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Add release note for wsgi containerization

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Change-Id: I9dba62379b713dff596de9c4fc25dceb77581bfa
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Brian Rosmaita 2017-07-20 22:11:07 -04:00
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releasenotes/notes/wsgi-containerization-369880238a5e793d.yaml Normal file
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---
features:
- |
Glance is now packaged with a WSGI script entrypoint, enabling it to be
run as a WSGI application hosted by a performant web server. See `Running
Glance in HTTPD
<https://docs.openstack.org/glance/latest/admin/apache-httpd.html>`_
in the Glance documentation for details.
There are some limitations with this method of deploying Glance and we
do not recommend its use in production environments at this time. See
the `Known Issues`_ section of this document for more information.
issues:
- |
Although support has been added for Glance to be run as a WSGI application
hosted by a web server, the atypical nature of the Images APIs provided by
Glance, which enable transfer of copious amounts of image data, makes it
difficult for this approach to work without careful configuration. Glance
relies on the use of chunked transfer encoding for image uploads, and
the support of chunked transfer encoding is not required by the
`WSGI specification`_.
The Glance documentation section `Running Glance in HTTPD`_ outlines some
approaches to use (and not to use) Glance with the Apache httpd server. This
is the way Glance is configured as a WSGI application in devstack, so it's
the method with which we've had the most experience. If you try deploying
Glance using a different web server, please consider contributing your
findings to the Glance documentation.
Currently, we are experiencing some problems in the gate when Glance is
configured to run in devstack following the guidelines recommended in the
documentation. You can follow `Bug 1703856`_ to learn more.
As far as the Glance team can determine, the difficulties running Glance
as a WSGI application are caused by issues external to Glance. Thus
the Glance team recommends that Glance be run in its normal standalone
configuration, particularly in production environments. If you choose
to run Glance as a WSGI application in a web server, be sure to test
your installation carefully with realistic usage scenarios.
.. _`WSGI specification`: https://www.python.org/dev/peps/pep-0333/
.. _`Running Glance in HTTPD`: https://docs.openstack.org/glance/latest/admin/apache-httpd.html
.. _`Bug 1703856`: https://bugs.launchpad.net/glance/+bug/1703856