Django with mod_wsgi how to set PYTHONHASHSEED env variable?

Question

How to run django with mod_wsgi with PYTHONHASHSEED environment variable set to random? Is it a good approach to set it in django settings like this?

os.environ['PYTHONHASHSEED'] = 'random'

Answer 1

mod_wsgi 4.1.0 introduces an option for this (http://modwsgi.readthedocs.org/en/latest/release-notes/version-4.1.0.html); you would add to your Apache config:

WSGIPythonHashSeed random

If you can't run that version, you have to set the variable in the startup environment of the Apache process, which will be OS-specific. For Fedora or RHEL 7, you can create /etc/systemd/system/httpd.service:

.include /lib/systemd/system/httpd.service
[Service]
Environment=PYTHONHASHSEED=random

then systemctl daemon-reload; systemctl restart httpd.service. For pre-systemd Red Hats, you can edit /etc/sysconfig/httpd. For Debian, it's /etc/apache2/envvars.

Here's a WSGI file to test if it's working (based on the example in the mod_wsgi docs):

import sys

def application(environ, start_response):
    status = '200 OK'

    try:
        hr = sys.flags.hash_randomization
        if hr == 0:
            output = 'Hash randomization disabled'
        elif hr == 1:
            output = 'Hash randomization enabled'
        else:
            output = 'Unknown hash randomization: ' + str(hr)
    except AttributeError:
        output = 'Hash randomization not supported'

    response_headers = [('Content-type', 'text/plain'),
                        ('Content-Length', str(len(output)))]
    start_response(status, response_headers)

    return [output]