glance/doc/source/admin/apache-httpd.rst
Doug Hellmann 1c7f556d4f rearrange existing documentation to follow the new layout standard
This change moves existing files, updates a few of the cross-references
and paths, and fixes some formatting. It is not meant to be the final
word on how the main page looks or how the other files are organized,
but it gets everything roughly into shape. If the glance team wants to
make changes, please do those as follow-up patches

This change depends on the spec and on a feature of pbr that allows us
to move where the auto-generated class reference documentation ends up
in the tree.

Depends-On: Ia750cb049c0f53a234ea70ce1f2bbbb7a2aa9454
Depends-On: I2bd5652bb59cbd9c939931ba2e7db1b37d2b30bb
Change-Id: I9dde267793a5913acb5b1ec028cfb66bc5189783
Signed-off-by: Doug Hellmann <doug@doughellmann.com>
2017-06-21 14:15:58 -04:00

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=======================
Running Glance in HTTPD
=======================
Since the Pike release Glance has packaged a wsgi script entrypoint that
enables you to run it with a real web server like Apache HTTPD or nginx. To
deploy this there are several patterns. This doc shows two common ways of
deploying Glance with Apache HTTPD.
uwsgi
-----
This is the current recommended way to deploy Glance with a real web server.
In this deployment method we use uwsgi as a web server bound to a random local
port. Then we configure apache using mod_proxy to forward all incoming requests
on the specified endpoint to that local webserver. This has the advantage of
letting apache manage all inbound http connections, but letting uwsgi manage
running the python code. It also means when we make changes to Glance code
or configuration we don't need to restart all of apache (which may be running
other services too) and just need to restart the local uwsgi daemon.
The httpd/ directory contains sample files for configuring HTTPD to run Glance
under uwsgi in this configuration. To use the sample configs simply copy
`httpd/uwsgi-glance-api.conf` to the appropriate location for your Apache
server. On Debian/Ubuntu systems it is::
/etc/apache2/sites-available/uwsgi-glance-api.conf
On Red Hat based systems it is::
/etc/httpd/conf.d/uwsgi-glance-api.conf
Enable mod_proxy by running ``sudo a2enmod proxy``
Then on Ubuntu/Debian systems enable the site by creating a symlink from the
file in ``sites-available`` to ``sites-enabled``. (This is not required on Red
Hat based systems)::
ln -s /etc/apache2/sites-available/uwsgi-glance-api.conf /etc/apache2/sites-enabled
Start or restart HTTPD to pick up the new configuration.
Now we need to configure and start the uwsgi service. Copy the
`httpd/glance-api-uwsgi.ini` file to `/etc/glance`. Update the file to match
your system configuration (for example, you'll want to set the number of
processes and threads).
Install uwsgi and start the glance-api server using uwsgi::
sudo pip install uwsgi
uwsgi --ini /etc/glance/glance-api-uwsgi.ini
.. NOTE::
In the sample configs port 60999 is used, but this doesn't matter and is
just a randomly selected number. This is not a contract on the port used
for the local uwsgi daemon.
mod_proxy_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
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 uwsgi 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.
You can work around these issues by configuring your apache proxy to buffer the
chunked data and send the full content length to uwsgi. 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
mod_wsgi
--------
This deployment method is not recommended for using Glance. The mod_wsgi
protocol does not support ``Transfer-Encoding: chunked`` and therefore makes it
unsuitable for use with Glance. However, you could theoretically deploy Glance
using mod_wsgi but it will fail on any requests that use a chunked transfer
encoding.