Apache Deployment Notes

April 19, 2021 ยท View on GitHub

The following has been tested on Ubuntu 12.04 and 14.04. Other recipes, suggestions, clarifications, corrections welcome!

These instructions assume you have (or will) run sudo ./setup.py install with the default configurations options.

You can get all of the dependencies from apt:

$ sudo apt-get install apache2 libapache2-mod-wsgi-py3

Next enable to require modules:

sudo a2enmod headers expires

Next edit the site configuration file /etc/apache2/sites-enabled/000-default.conf with your editor of choice (you'll need root privileges; the name may be different; if there is no site symlinked in the directory, enable the site with, for example a2ensite 000-default.conf).

Now add something to this affect:

ExpiresActive On
ExpiresDefault "access plus 5184000 seconds"

AllowEncodedSlashes On

WSGIDaemonProcess loris user=loris group=loris processes=10 threads=15 maximum-requests=10000
WSGIScriptAlias /loris /var/www/loris/loris.wsgi
WSGIProcessGroup loris

Note: from Python 3.8 and later, you will get a RuntimeError: fork not supported for subinterpreters when rendering JPEG2000 source images. To fix this, change the WSGIScriptAlias to the following:

WSGIScriptAlias /loris /var/www/loris/loris.wsgi process-group=loris application-group=%{GLOBAL}

Explanation:

  • ExpiresActive On and ExpiresDefault sets the Cache-Control and Expires headers, e.g. with the setting above responses will include (assuming I made the request at Sat, Nov 23 2013 19:45:20 GMT):
< Cache-Control: max-age=5184000
< Expires: Wed, 22 Jan 2014 19:45:20 GMT

5184000 = 60 days.

(Loris is setting the Last-Modified header based on the file system metadata.)

  • AllowEncodedSlashes On lets %2F though in requests (they're allowed but must be escaped in the identifier portion of the URI). Depending on your hosting environment, this may need to be explicitly declared inside a VirtualHosts container as AllowEncodedSlashes is not inherited by VirtualHosts if declared in a global context (see Apache Bug 46830).

  • WSGI Flags. Have a look at the mod-wsgi configuration guidelines. In general is seems like a good idea to prefer threads over processes; (check out this answer on serverfault).

If you would like Loris's access logs to be kept in a separate file you can add:

SetEnvIf Request_URI ^/loris loris
CustomLog ${APACHE_LOG_DIR}/loris-access.log combined env=loris

The first argument to SetEnvIf Request_URI should match the first argument to WSGIScriptAlias above, plus a leading ^.

On RedHat only you'll likely need to add:

WSGISocketPrefix /var/run/wsgi

as well. See: Location of Unix Sockets.

Finally, restart Apache and have a look (start at http://{your_server}/loris).

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