Flask hello world using apache and mod_wsgi shows

I'm attempting to run the basic hello.py from the flask site over apache2 using wsgi. Here is what my code looks like:

/var/www/flask_dev/hello.py

from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello World!'

if __name__ == '__main__':
    app.run()

/var/www/flask_dev/start.wsgi

from hello import app as application

import sys
sys.stdout = sys.stderr

/etc/apache2/sites-available/flask_dev.conf

#Listen 80
ServerName example.com

<VirtualHost *:80>
    # The ServerName directive sets the request scheme, hostname and port that
    # the server uses to identify itself. This is used when creating
    # redirection URLs. In the context of virtual hosts, the ServerName
    # specifies what hostname must appear in the request's Host: header to
    # match this virtual host. For the default virtual host (this file) this
    # value is not decisive as it is used as a last resort host regardless.
    # However, you must set it for any further virtual host explicitly.
    #ServerName www.example.com

    ServerAdmin webmaster@localhost
    #ServerName example.com

    WSGIDaemonProcess hello user=<myuser> group=<myusersgroup> threads=5 python-path=/var/www/flask_dev

    WSGIScriptAlias / /var/www/flask_dev/start.wsgi
    <Directory /var/www/flask_dev>
           WSGIProcessGroup hello
           WSGIApplicationGroup %{GLOBAL}
           Order deny,allow
           Allow from all
    </Directory>

    # Available loglevels: trace8, ..., trace1, debug, info, notice, warn,
    # error, crit, alert, emerg.
    # It is also possible to configure the loglevel for particular
    # modules, e.g.
    #LogLevel info ssl:warn

    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined

    # For most configuration files from conf-available/, which are
    # enabled or disabled at a global level, it is possible to
    # include a line for only one particular virtual host. For example the
    # following line enables the CGI configuration for this host only
    # after it has been globally disabled with "a2disconf".
    #Include conf-available/serve-cgi-bin.conf
</VirtualHost>

# vim: syntax=apache ts=4 sw=4 sts=4 sr noet

/etc/hosts

127.0.0.1    example.com

After I run sudo a2ensite flask_dev and sudo service apache2 reload (or restart), going to www.example.com just gives the files in the webroot. ~~I've checked the error log and it looks like mod_wsgi and mod_python are starting up. Does anyone know what else I'm missing?~~

Edit 1 I'm now able to see messages from the error log, and it looks like I am affected by https://bugs.launchpad.net/ubuntu/+source/libapache2-mod-python/+bug/1073147 on Ubuntu 12.04.

I will try recompiling later to the correct Python version to see if it fixes the error. For now, while this error occurs, I'm still seeing the files listed when I visit example.com.

error.log

[Mon Jan 13 11:28:06 2014] [notice] caught SIGTERM, shutting down
[Mon Jan 13 11:28:07 2014] [error] python_init: Python version mismatch, expected '2.7.2+', found '2.7.3'.
[Mon Jan 13 11:28:07 2014] [error] python_init: Python executable found '/usr/bin/python'.
[Mon Jan 13 11:28:07 2014] [error] python_init: Python path being used '/usr/lib/python2.7/:/usr/lib/python2.7/plat-linux2:/usr/lib/python2.7/lib-tk:/usr/lib/python2.7/lib-old:/usr/lib/python2.7/lib-dynload'.
[Mon Jan 13 11:28:07 2014] [notice] mod_python: Creating 8 session mutexes based on 6 max processes and 25 max threads.
[Mon Jan 13 11:28:07 2014] [notice] mod_python: using mutex_directory /tmp 
[Mon Jan 13 11:28:07 2014] [warn] mod_wsgi: Compiled for Python/2.7.2+.
[Mon Jan 13 11:28:07 2014] [warn] mod_wsgi: Runtime using Python/2.7.3.
[Mon Jan 13 11:28:07 2014] [notice] Apache/2.2.22 (Ubuntu) mod_python/3.3.1 Python/2.7.3 mod_wsgi/3.3 configured -- resuming normal operations

Edit 2 Updating to 13.04 has solved the version info. Now when I go to example.com I get a 403 forbidden error. When I tail the error.log I see:

[Mon Jan 13 21:03:41.464815 2014] [:error] [pid 10999:tid 3014634304] [client 127.0.0.1:35067] Attempt to invoke directory as WSGI application: /var/www/flask_dev/

I've tried adding AddHandler cgi-script py to my flask_dev.conf, but that doesn't seem to work either.

Has anyone gotten this kind of error with a WSGI application before and know of a workaround for this?

Thanks in advance.

Edit 3 All source code works now

in /var/www/flask_dev/hello.wsgi you should be importing app not ass. Second you should not be using DocumentRoot to store your scripts. DocumentRoot is for storing static files and so it will certainly list them as files and never run them as script.

Try using

    WSGIScriptAlias / /var/www/flask_dev/hello.wsgi
    <Directory "/var/www/flask_dev">
       WSGIProcessGroup hello
       WSGIApplicationGroup %{GLOBAL}
       Order deny,allow
       Allow from all
    </Directory>

Check this page.