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Contents 1 Bootstrap 2 Quirks 3 Using Flup 4 Troubleshooting 5 See Also

Bootstrap

The following is a quick procedure for establishing a sanity-test FCGI application running Python.

1. If your website is being hosted on an Apache2 server (almost all new domains will be that way), contact the DreamHost support team asking us to change the Apache2 memory restriction to be compatible with Python/FastCGI. For some reason it doesn't work with the setup we have in place. Unfortunately we can't change the setup due to bad PHP processes eating tons of memory.
2. On the panel configure your site for "Fast CGI Support?" found under (Domains->Manage Domains)->(yourdomain.com->Edit)->PHP Support
3. Download the Allan Saddi's fcgi.py, placing it somewhere in your PYTHONPATH
4. Create your default page handler, dispatch.fcgi (You must use dispatch.fcgi or you will find that the process is killed in the middle of execution. This is explained here)

   #!/usr/bin/env python
   
   def myapp(environ, start_response):
       start_response('200 OK', [('Content-Type', 'text/plain')])
       return ['Hello World!\n']
   
   if __name__ == '__main__':
       from fcgi import WSGIServer
       WSGIServer(myapp).run()
   

5. Make dispatch.fcgi executable. Be sure that it is not group-writable, or you may get a 500 Internal Error.

   chmod 755 dispatch.fcgi
   

6. Create an .htaccess file to point to redirect all requests to this script

   RewriteEngine On
   RewriteBase /
   RewriteRule ^dispatch\.fcgi/ - [L]
   RewriteRule ^(.*)$ dispatch.fcgi/$1 [L]
   

7. Wait for the magical dreamhost refresh daemon to notice all your updates (try 'touch dispatch.fcgi')
8. Load the page

Quirks

I had a few problems getting FCGI and Python to work together, so here's what I did.

First I asked the DreamHost support team to change the Apache2 memory restriction to be compatible with Python/FastCGI, second I asked them to raise the Apache softlimit for my account.

If they set everything up for you, Python FastCGI scripts should work on your server... with a little bit of work.

Here's what I had to do myself: I downloaded Virtual Python...

wget http://peak.telecommunity.com/dist/virtual-python.py

then I created a directory called "packages" to install things into.

mkdir ~/packages

Next I added the folowing code to my ~/.bashrc and ~/.bash_profile:

export PYTHONPATH="$HOME/packages/lib/python2.3/site-packages"
export LD_LIBRARY_PATH="$HOME/packages/lib"
export PATH="$HOME/packages/bin:$PATH"

I then ran virtual python's installer and told it to install into "packages" rather than my home directory.

python virtual-python.py --prefix packages/

Optional: To install easy_install I ran:

wget http://peak.telecommunity.com/dist/ez_setup.py
python ez_setup.py

Lastly, I downloaded Allan Saddi's fcgi.py and placed it in ~/packages/lib/python2.3/site-packages. You can alternately use Flup, as shown below.

To test my virtual python and fcgi installation I loosely followed some instructions from Django: I saved the following code in a file called dispatch.fcgi on ~/yourdomain.com

#!/home/my-username/packages/bin/python
from fcgi import WSGIServer
def test_app(environ, start_response):
    start_response('200 OK', [('Content-Type', 'text/plain')])
    yield 'Hello, world!\n'

WSGIServer(test_app).run()

Then I made it executable and created a .htaccess file in the same directory as dispatch.fcgi:

chmod a+x ~/yourdomain.com/dispatch.fcgi

.htaccess

RewriteEngine On
RewriteBase /
RewriteRule ^dispatch\.fcgi/ - [L]
RewriteRule ^(.*)$ dispatch.fcgi/$1 [L]

Finally, I waited a few minutes, and tried http://www.mydomain.com/dispatch.fcgi and it worked! --CPUFreak91

Using Flup

As an alternate to using fcgi.py, you can rely on Flup to use FastCGI on DreamHost. If you choose to do so (and this was the only way Python worked for me), you don't need to download or install fcgi.py. Simply install Flup with easy_install.

easy_install Flup

I also found that you need to add import sys to your dispatch file. You new dispatch.fcgi file should look like below

#!/home/my-username/packages/bin/python

import sys

from flup.server.fcgi_fork import WSGIServer

def test_app(environ, start_response):
    start_response('200 OK', [('Content-Type', 'text/plain')])
    yield 'Hello, world!\n'

WSGIServer(test_app).run()

No changes are required to your .htaccess file or anything else. Once your Hello World works, you're ready to start using Python. Simply install what you need via easy_install and away you go.

NOTE This is just what worked for me. I have no idea if there are any side effects from including the import sys line or using Flup. --Skeezer65134

Troubleshooting

You can diagnose a lot of errors by running dispatch.fcgi from the commandline:

./dispatch.fcgi

You can ignore "WSGIServer: missing FastCGI param" errors.

If you are getting a 500 Internal Error, try changing the permissions so that dispatch.fcgi is not group-writable. Something like this will work:

chmod 755 dispatch.fcgi

See Also

• Python
• FastCGI
• Django - Python Web Application Framework often deployed via FastCGI