openstack/glance
Code Issues Proposed changes
3e2c555701
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

3.8 KiB
Raw Blame History

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.