FastCGI, et. al.

I've been wanting to drop mod_python since the day I installed it. After the saga of setting it up, I was left feeling unclean. So I sat down yesterday and started downloading new versions of stuff. Apache, mod_fastcgi, Python, Subversion, PHP... you name it. My biggest concerns were upgrading to Python 2.5, and switching this site (and others) from mod_python to mod_fastcgi. But I sure am glad I did. Deploying a Django site was never my favorite thing to do under mod_python, but with mod_fastcgi, it became an almost joyous experience.

Here's the VirtualHost entry for this site running under mod_python: 

<VirtualHost *:80>
    ServerName theidioteque.net
    ServerAlias www.theidioteque.net
    <Location />
        SetHandler python-program
        PythonPath "['/home/dcwatson/projects'] + sys.path"
        PythonHandler django.core.handlers.modpython
        SetEnv DJANGO_SETTINGS_MODULE idioteque.settings
        PythonDebug Off
    </Location>
    Alias /static /home/dcwatson/projects/idioteque/static
    <Location /static/>
        SetHandler None
    </Location>
</VirtualHost>

And here it is running under mod_fastcgi: 

<VirtualHost *:80>
    ServerName theidioteque.net
    ServerAlias www.theidioteque.net
    Alias /static /home/dcwatson/webapps/idioteque/static
    ScriptAlias / /home/dcwatson/webapps/idioteque.fcgi/
</VirtualHost>

Note the trailing slash at the end of the .fcgi script. Forget it, and your links won't work. My idioteque.fcgi script looks just like the one found on django's fastcgi documentation.

Setting up trac was just as easy. I simply copied the trac.fcgi script to my own trac-idioteque.fcgi script and set the TRAC_ENV environment variable at the top of it, as described here. Now my VirtualHost entry is three lines: 

<VirtualHost *:80>
    ServerName code.theidioteque.net
    Alias /chrome/common /usr/local/python/share/trac/htdocs
    ScriptAlias / /home/dcwatson/webapps/trac-idioteque.fcgi/
</VirtualHost>

I should probably note that I have Allow from all set in my root Directory in httpd.conf. This is probably not a terribly good idea, but it saves explicitly allowing access to any directory I want to serve files from.

Apologies for the particularly dry post, but if you haven't noticed, this blog seems to be geared around problems I encounter and my solutions to them. If your problem is mod_python, mod_fastcgi is your solution.

Comments

Noah
October 05, 2006

I heard it wasn't good to run Django with FastCGI, is there a reason for this or is it just a rumor?

Dan
October 10, 2006

Where did you hear that? While the Django docs specifically endorse the mod_python route, there are official instructions for setting it up using FastCGI. I've found it to be fewer lines of configuration, and more stable in my case.

James Crasta
October 11, 2006

Curious, I had no idea using a ScriptAlias like that would work. Do you have any FastCGIServer or AddHandler directives listed?

I ask this because I wrote the current fastcgi documentation that's on djangoproject.com, and because I was unable to find any other workable alternatives, I ended up having the docs use mod_rewrite. (I use lighttpd in all my current deployments, and so apache config came as an afterthought)

I wonder, is Apache calling that script using CGI and not FastCGI? Flup will fall back to serving normal CGI if the script is called without the proper fcgi environment / file descriptors. One thing to do would be to check the output of ps ax and see if there's a persistent fcgi process running or if it only spawns per-request.

I'm rather intrigued as to how your setup is working; feel free to fire me off an email, perhaps I'll use your setup in future versions of the fastcgi documentation.

Dan
October 11, 2006

I probably should have mentioned I do have an AddHandler line in my httpd.conf: 

AddHandler fastcgi-script .fcgi

I don't use a FastCGIServer/FastCGIExternalServer line because they can't be used in VirtualHost blocks, and I like to keep things as organized and isolated as possible. One of the first things I did was check the output of ps aux - one persistent instance is created the first time the site is hit.

Django
October 14, 2006

I'm gonna have to try this on my host to see if I can get it working. Many hosts dont support mod_python.

ross lazarus
November 02, 2006

On centos (selinux), you probably also need to add FastCgiIpcDir /var/www/html/fastcgiIPC

It took me a while to figure this out - the apache process complains about not being able to bind() .

Matthias Urlichs
December 14, 2006

For obvious reasons, I would recommend that the next part of this tutorial should come out tomorrow, and deal with the topic of "how do I integrate captcha support into the Django comment system".

:-/

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