[[PageOutline(2-5,Contents,pullout)]]

= Alternative frontends for development

== Alternative frontend: mod_python

Virtualenv can be used with '''Apache''' and '''mod_python''', but as mod_python will be a system install, it will not be aware of the virtualenv without some configuration. For development this is useful as one Apache server can serve various development versions in a more permanent way. This method will use the system Python, but will add the libraries from the virtualenv.

 1. Make a new frontend script that for instance can be stored in the virtualenv `bin` directory:
 {{{#!python
#myvirtualtrac.py

import os
import site
site.addsitedir('/path/to/my/virtualenv/lib/python2.4/site-packages')

from trac.web.modpython_frontend import handler
}}}
 1. Update Apache config to use this script. Add or update options according to the default mod_python setup like for instance found in TracModPython:
 {{{#!apache
# Extend the path so Apache will find your script on path
PythonPath "['/path/to/my/virtualenv/bin'] + sys.path"

# Make mod_python use new frontend instead of trac.web.modpython_frontend
PythonHandler myvirtualtrac
}}}

== Alternative frontend: mod_wsgi

With Apache, '''mod_wsgi''' is a very good alternative to '''mod_python'''. Setting this up follows the same pattern, but for development especially there is one major advantage: it can quite easily be set up to auto-reload on code changes.

 1. Update a default TracModWsgi setup to make a daemonised process, and as of mod_wsgi 2.0 (this setup depends on >= 2.0) there is built-in support for custom paths and similar. Example of a full `VirtualHost` configuration:
 {{{#!apache
<VirtualHost *:80>
    ServerName virtualtrac.local

    # Update user and group to be whatever on your system is intended to run the deamon
    # Update the paths to point to virtualenv site-packages (for trac+++) and bin (for script)
    WSGIDaemonProcess virtualtrac user=www group=www threads=25 python-path=/path/to/my/virtualenv/lib/python2.4/site-packages:/path/to/my/virtualenv/bin

    WSGIScriptAlias / /path/to/my/virtualenv/bin/virtualtrac.wsgi

    <Location />
      WSGIReloadMechanism Process
      WSGIProcessGroup virtualtrac
      # GLOBAL should generally be used instead of SERVER, see http://code.google.com/p/modwsgi/wiki/IntegrationWithTrac
      WSGIApplicationGroup %{GLOBAL}
      Order deny,allow
      Allow from all
    </Location>

    # Authentication
    <LocationMatch (/[^/.]+/login)>
      # Note: Change settings with regards to auth method, paths and domain
      AuthType Digest
      AuthName "virtualtrac"
      AuthDigestDomain /trac http://virtualtrac.local
      AuthDigestProvider file
      AuthUserFile /path/to/access.htdigest
      Require valid-user
    </LocationMatch>

</VirtualHost>
}}}
 1. Go to [mod-wsgi:ReloadingSourceCode#Monitoring_For_Code_Changes ReloadingSourceCode] and save the Python script as `/path/to/my/virtualenv/bin/monitor.py` 
 1. A basic WSGI frontend script, save as `/path/to/my/virtualenv/bin/virtualtrac.wsgi`:
 {{{#!python

import sys
sys.stdout = sys.stderr

import os
os.environ['TRAC_ENV_DIR'] = '/path/to/trac/project'
# or, alternatively for multiple projects
#os.environ['TRAC_ENV_PARENT_DIR'] = "/parent/path/to/many/projects"
os.environ['PYTHON_EGG_CACHE'] = '/path/to/a/temp/to/cache/eggs'

import trac.web.main

import monitor
monitor.start(interval=1.0)
# Additionally monitor easy-install.pth to restart whenever installs are done
monitor.track('/path/to/my/virtualenv/lib/python2.4/site-packages/easy-install.pth')

application = trac.web.main.dispatch_request
}}}