Table Of Contents

• FastCGI
  • Creating a .fcgi file
  • Configuring lighttpd
  • Configuring nginx

FastCGI

A very popular deployment setup on servers like lighttpd and nginx is FastCGI. To use your WSGI application with any of them you will need a FastCGI server first.

The most popular one is flup which we will use for this guide. Make sure to have it installed.

Creating a .fcgi file

First you need to create the FastCGI server file. Let’s call it yourapplication.fcgi:

#!/usr/bin/python
from flup.server.fcgi import WSGIServer
from yourapplication import make_app

application = make_app()
WSGIServer(application).run()

This is enough for Apache to work, however lighttpd and nginx need a socket to communicate with the FastCGI server. For that to work you need to pass the path to the socket to the WSGIServer:

WSGIServer(application, bindAddress='/path/to/fcgi.sock').run()

The path has to be the exact same path you define in the server config.

Save the yourapplication.fcgi file somewhere you will find it again. It makes sense to have that in /var/www/yourapplication or something similar.

Make sure to set the executable bit on that file so that the servers can execute it:

# chmod +x /var/www/yourapplication/yourapplication.fcgi

Configuring lighttpd

A basic FastCGI configuration for lighttpd looks like that:

fastcgi.server = ("/yourapplication" =>
    "yourapplication" => (
        "socket" => "/tmp/yourapplication-fcgi.sock",
        "bin-path" => "/var/www/yourapplication/yourapplication.fcgi",
        "check-local" => "disable"
    )
)

This configuration binds the application to /yourapplication. If you want the application to work in the URL root you have to work around a lighttpd bug with the ~werkzeug.contrib.fixers.LighttpdCGIRootFix middleware.

Make sure to apply it only if you are mounting the application the URL root.

Configuring nginx

Installing FastCGI applications on nginx is a bit tricky because by default some FastCGI parameters are not properly forwarded.

A basic FastCGI configuration for nginx looks like this:

location /yourapplication/ {
    include fastcgi_params;
    if ($uri ~ ^/yourapplication/(.*)?) {
        set $path_url $1;
    }
    fastcgi_param PATH_INFO $path_url;
    fastcgi_param SCRIPT_NAME /yourapplication;
    fastcgi_pass unix:/tmp/yourapplication-fcgi.sock;
}

This configuration binds the application to /yourapplication. If you want to have it in the URL root it’s a bit easier because you don’t have to figure out how to calculate PATH_INFO and SCRIPT_NAME:

location /yourapplication/ {
    include fastcgi_params;
    fastcgi_param PATH_INFO $fastcgi_script_name;
    fastcgi_param SCRIPT_NAME "";
    fastcgi_pass unix:/tmp/yourapplication-fcgi.sock;
}

Since Nginx doesn’t load FastCGI apps, you have to do it by yourself. You can either write an init.d script for that or execute it inside a screen session:

$ screen
$ /var/www/yourapplication/yourapplication.fcgi