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Merge "Return the mod_proxy_uwsgi paragraph" into stable/train

changes/53/744153/1
Zuul 5 days ago
committed by Gerrit Code Review
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d53dd566c5
1 changed files with 38 additions and 4 deletions
  1. +38
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      doc/source/admin/apache-httpd.rst

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doc/source/admin/apache-httpd.rst View File

@@ -36,10 +36,44 @@ The clearest we can say is just don't do it.
mod_proxy_uwsgi
'''''''''''''''

This has not been doable since Ussuri as we only support Python 3.

In theory the same applies as mod_wsgi but even without chunked encoding the
code is still broken under uwsgi.
.. WARNING::

Running Glance under HTTPD in this configuration will only work on Python 2
if you use ``Transfer-Encoding: chunked``. Also if running with Python 2
Apache will be buffering the chunked encoding before passing the request
on to uWSGI. See bug: https://github.com/unbit/uwsgi/issues/1540
The async tasks, namely (by default) admin only tasks API and Interoperable
Image Import will not work under uWSGI even with proxying. There might be
problems with reload and graceful shutdowns of the service that are not
documented elsewhere. Treat this as any uWSGI deployment, not supported.

Instead of running uWSGI as a webserver listening on a local port and then
having Apache HTTP proxy all the incoming requests with mod_proxy. The
normally recommended way of deploying the uWSGI server with Apache HTTPD is to
use mod_proxy_uwsgi and set up a local socket file for uWSGI to listen on.
Apache will send the requests using the uwsgi protocol over this local socket
file. However, there are issues with doing this and using chunked-encoding, so
this is not recommended for use with Glance.

You can work around these issues by configuring your Apache proxy to buffer the
chunked data and send the full content length to the uWSGI server. You do this
by adding::

SetEnv proxy-sendcl 1

to the apache config file using mod_proxy_uwsgi. For more details on using
mod_proxy_uwsgi see the official docs:
http://uwsgi-docs.readthedocs.io/en/latest/Apache.html?highlight=mod_uwsgi_proxy#mod-proxy-uwsgi

There are some additional considerations when doing this though. Having Apache
locally buffer the chunked data to disk before passing it to uWSGI means you'll
need to have sufficient disk space in /tmp (or whatever you set TMPDIR to) to
store all the disk files. The other aspect to consider is that this buffering
can take some time to write the images to disk. To prevent random failures
you'll likely have to increase timeout values in the uWSGI configuration file
to ensure uWSGI will wait long enough for this to happen. (Depending on the
uploaded image file sizes it may be necessary to set the timeouts to multiple
minutes.)

mod_wsgi
--------


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