Knowledgebase: How-To
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Using Python with FastGCI
Posted by on 02 July 2012 11:03 AM
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Plain Old Python with FastCGIThe first part of these instructions are similar to Django on FastCGI. First, obtain shell access and then cd ~/www mkdir project cd project wget h p://svn.saddi.com/py-lib/trunk/fcgi.py chmod 755 fcgi.py FastCGI works based on a .fcgi file and it detects reloads based on timestamps. For this reason and that you probably don't want your Python project to be entirely wri en for FastCGI, you probably want to use .htaccess to route everything through a dispatch.fcgi file as Django does. First, the < >project/.htaccess: RewriteEngine On
RewriteBase /project
RewriteCond %{REQUEST_URI} !^/project/dispatch.fcgi [NC]
RewriteCond %{REQUEST_URI} !^/project/static [NC]
RewriteCond %{REQUEST_URI} !^/project/more_static [NC]
RewriteCond %{REQUEST_URI} !\.(css|png|jpg|gif)$ [NC]
RewriteRule ^(.*)$ dispatch.fcgi/$1 [QSA,NC]
You can add more lines to ignore folders as we did in the example < >static and < >more_static folder or include more file extensions to ignore. That way those files aren't routed through our dispatcher and will be efficiently served by Apache instead. Note that we are appending URLs to < >dispatch.fcgi, which we can parse later with the < >urlparse library and < >cgi.FieldStorage. Now, create < >project/dispatch.fcgi with Unix line endings. You will receive puzzling FastCGI errors if you use any other line endings, especially if you are on Windows like me and don't like spending hours on end diagnosing puzzling FastCGI errors. #!/usr/bin/env python
# This must be in Unix line endings
import sys
from fcgi import WSGIServer
import application
import cgi
class Request(object): pass
def app(e, start_response):
req = Request()
# POST data
req.form = cgi.FieldStorage(fp = e['wsgi.input'], environ = e)
# GET data
req.params = cgi.parse_qs(e['QUERY_STRING'])
start_response('200 OK', [('Content-type', 'text/html')])
return [application.start(req)]
WSGIServer(app).run()
The script, as above, can employ the environ variables and can call any one of your functions in your application stored in another file such as < >start in < >application.py. From that, you can then actually dispatch to the right module to handle the request based on where < >PATH_INFO is or start your application logic. Before accessing it and possibly forcing FastCGI to generate a broken cache (see below), type < >python dispatch.fcgi in your shell. You should see some output although the environ variables aren't set properly from the shell. If you see Python errors, though, this is a quick way to partially debug your application without having to go through FastCGI just yet. Now navigate to < >example.com/project/ or whereever and you should see output. Remember: < >example.com/project/jobs maps to < >example.com/project/dispatch.fcgi/jobs due to < >.htaccess. Tips
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