Background: Often with a python web framework using ToscaWidgets, you
will want to serve your static files with Apache so they will download
faster. The typical solution involves having ToscaWidgets generate
the appropriate Apache configuration text to serve the files
statically.
Problem: The downside to this typical solution is that every time you
create a new widget, you have to re-generate the configuration and
reload Apache.
Solution: I have a solution that uses some advanced features of
mod_rewrite to do this on-the-fly. My solution uses a mod_rewrite
External Rewriting Engine, which is just a few lines of python code
that convert a URL into the appropriate file path.
1. Apache configuration
Let's say you have your web framework (TurboGears, Pylons, or
whatever) running on port 8080. You want URL's that start with "/
toscawidgets/resources" to go through the External Rewriting Engine
and get converted into file paths, and you want all other URLs to be
proxied to the web framework. Make sure you have mod_rewrite compiled
and loaded, and then put something like this inside your Server or
VirtualHost configuration block:
RewriteEngine On
RewriteMap toscawidgets prg:/path/to/mapper.sh
RewriteRule ^/toscawidgets/resources/(.*) ${toscawidgets:$1} [L]
RewriteRule ^/(.*) http://127.0.0.1:8080/$1 [P,L]
Not too difficult, right? The first line turns on mod_rewrite's
RewriteEngine for this Server or VirtualHost. The next line declares
a "RewriteMap" that points towards a shell script that's responsible
for doing the External Rewriting (we'll look at that in step 2,
below). The third line says that for all URLs beginning with /
toscawidgets/resources, send the rest of the URL to the 'toscawidgets'
RewriteMap, which is responsible for returning a file path where the
specified resource lives. The final line proxies all other requests
to the web framework, like normal.
2. External Rewriting Engine
So the mapper.sh we specified is our External Rewriting Engine. Wait,
did I say it was written in python? It is! The shell just activates
the WorkingEnv that I happen to use, and then exec's the python
script. You could use the shell script to set your PYTHONPATH, or
skip the shell script entirely and use mapper.py as your mapper
instead. I use WorkingEnv though, so I need the shell script in front
of the python script. My mapper.sh looks like this:
----[snip]----
#!/bin/bash
# Activate workingenv
source /path/to/myenv/bin/activate
# Call mapper script
exec ./mapper.py
----[snip]----
And then the real work is done by this simple python script, which
accepts the URL pieces sent by that RewriteRule (from line 3 of step
1) on stdin, figures out which file should be served, and prints the
absolute path to that file to stdout. mapper.py looks like this:
----[snip]----
#!/usr/bin/python
import sys
import string
import os
import pkg_resources
while True:
data = string.strip(sys.stdin.readline())
if not data:
print "NULL"
else:
path_pieces = data.split("/")
module_name = path_pieces[0]
file_name = pkg_resources.resource_filename(
module_name,
os.path.join(*path_pieces[1:])
)
file_path = os.path.abspath(file_name)
print file_path
sys.stdout.flush()
----[snip]----
3. Framework Configuration
Your framework will probably need to know you're deploying it behind a
proxy. For TurboGears, you just have to add this to your dev.cfg or
prod.cfg file:
base_url_filter.on = True
base_url_filter.use_x_forwarded_host = True
4. You're done!
Isn't open source amazing! Congratulate yourself with a nice glass of
juice or tea! Remember to get up and stretch. Enjoy life!
-Ian Charnas
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"TurboGears" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/turbogears?hl=en
-~----------~----~----~----~------~----~------~--~---
