Getting Started

In my effort to explore various frameworks, I now turn to TurboGears2. The project is called Edumacate and the aim is to create a simple, elegant, blackboard killer.

I'm running Ubuntu 9.04 (Jaunty) and I'll step through the following setup:

• python-virtualenv
• TurboGears2
• Apache2
• mod_wsgi

Why use python-virtualenv?
TurboGears2 is a fan of python2.5, Ubuntu is a fan of python2.6, and I'm a fan of not having to resolve version conflicts.

python --version
sudo apt-get install python2.5
sudo apt-get install python-virtualenv
# Here I set up a shared environment for all wsgi apps that may need python2.5
cd /usr/local/lib # or wherever you stick your shared libraries
sudo virtualenv --python=python2.5 --no-site-packages python2.5-wsgi
source python2.5-wsgi/bin/activate # use the new environment
python --version
deactivate # go back to the regular python environment

Install TG2 using the new environment

sudo apt-get install python2.5-dev
sudo mkdir /var/webapps/
sudo chown `whoami`:`whoami` -R /var/webapps
cd /var/webapps/
# Use and modify the virtual environment we just created
sudo su -
source /usr/local/lib/python2.5-wsgi/bin/activate
easy_install -i \
http://www.turbogears.org/2.0/downloads/current/index \
tg.devtools
deactivate
exit
# verify that it installed correctly by running help
source /usr/local/lib/python2.5-wsgi/bin/activate
paster --help

Creating the project using TG2
(still in the new environment)

paster quickstart
Edumacate
edumacate
yes
cd Edumacate

Create the project-specific virtual environment
(in /var/webapps/Edumacate)
(using python2.5-wsgi)

virtualenv --python=python2.5 py2.5-edumacate
deactivate # now to the generic environment
source py2.5-edumacate/bin/activate
python --version

Test the project in the new environment

easy_install -i \
http://www.turbogears.org/2.0/downloads/current/index \
tg.devtools
python setup.py develop
paster serve development.ini &
# visit http://localhost:8080/ in a browser on the local machine
# (links2 is a great cli browser if your server is headless)

As a test that I did get two unique virtual environments with no extra libraries I'll install a new library in the default environment and see if I get it in either of the other two.

deactivate
python
>> import mutagen
Traceback (most recent call last):
File "", line 1, in
ImportError: No module named mutagen
# CTRL-D
sudo apt-get install python-mutagen
python
>> import mutagen
# CTRL-D
source py2.5-edumacate/bin/activate
python
>> import mutagen
Traceback (most recent call last):
File "", line 1, in
ImportError: No module named mutagen
# CTRL-D

Good, it works (and doesn't work) as expected. (mutagen is an ID3 / audio tagging library that I plan on using in another project)

Configure Edumacate for Apache
You need to have a python egg cache directory that apache can write to

cd /var/webapps/Edumacate
mkdir py2.5-edumacate/wsgi-cache
sudo chown www-data:www-data py2.5-edumacate/wsgi-cache
mkdir wsgi-config
vim wsgi-config/wsgi-development.py

import os, sys, site

os.environ['PYTHON_EGG_CACHE'] = '/var/webapps/Edumacate/py2.5-edumacate/wsgi-cache'

site.addsitedir('/var/webapps/Edumacate/py2.5-edumacate/lib/python2.5/site-packages')

sys.path.insert(0, '/var/webapps/Edumacate')
sys.path.insert(1, '/var/webapps/Edumacate/py2.5-edumacate/lib/python2.5')

from paste.deploy import loadapp

application = loadapp('config:/var/webapps/Edumacate/edumacate/config/development.ini')

Configure Apache for Edumacate

sudo apt-get install libapache2-mod-wsgi
sudo vim /etc/apache2/mods-enabled/wsgi.conf

# add the following line with the path to the environment you share among all of your TG2 webapps
WSGIPythonHome /usr/local/lib/python2.5-wsgi

sudo touch /etc/apache2/sites-available/edumacate-dev
sudo a2ensite edumacate-dev
sudo vim /etc/apache2/sites-enabled/edumacate-dev

<VirtualHost *:80>
  ServerName edumacate.coolaj86.info
  # we'll make the root directory of the domain call the wsgi script
  WSGIScriptAlias / /var/webapps/Edumacate/wsgi-config/wsgi-deployment.py

  # You can tweak this next line to your heart's content
  # based on the mod_wsgi documentation, but this should work for now.
  #WSGIDaemonProcess myuser threads=1 display-name=%{GROUP}
  #WSGIProcessGroup myuser

  # make the wsgi script accessible
  <Directory /var/webapps/Edumacate/wsgi-config>
  Order allow,deny
  Allow from all
  </Directory >

  # We'll need to create exceptions for all static content.
  # Aliases to serve general project media
  Alias /styles /var/webapps/Edumacate/edumacate/public/styles
  Alias /admin /var/webapps/Edumacate/edumacate/public/admin
  Alias /images /var/webapps/Edumacate/edumacate/public/images
  Alias /scripts /var/webapps/Edumacate/edumacate/public/scripts
  # Make all the static directories accessible
  <Directory /var/webapps/Edumacate/edumacate/public>
  Order allow,deny
  Allow from all
  </Directory >
</VirtualHost>

Test and Complete

sudo /etc/init.d/apache2 restart
# Browse to http://edumacate.coolaj86.info

Resources:
http://simplestation.com/locomotion/mod_wsgi-with-apache-2-on-centos-4/
http://simplestation.com/locomotion/turbogears-2-tg2-with-mod_wsgi-and-virtual-environments/