Python¶

FastCGI¶

This is a generic FCGI how-to for Python applications. Although we use Jon's FCGI Python library for this example, you can use any valid Python FCGI module for your own setup.

Requirements¶

1. LiteSpeed Web Server
2. Python
3. Jon's Python FCGI library: jonpy.sourceforge.net

Setup¶

Create a Virtual Host for this setup. From now on we will refer to this vhost as PythonVhost.

Save the following sample Python FCGI application to a path of your choice. We will call this app demoapp.py for tutorial purposes:

#!/usr/bin/python
import jon.cgi as cgi
import jon.fcgi as fcgi
from cgi import escape
import traceback

class Handler(cgi.Handler):
  def process(self, req):
    req.set_header("Content-Type", "text/html")
    req.write("Hello Python! Hello LiteSpeed!<hr size=1>")
    keys = req.environ.keys()
    keys.sort()
    for k in keys:
        req.write(escape(k) + " = " + escape(req.environ[k]) + "<br>")
    req.write(traceback.print_exc())

fcgi.Server({fcgi.FCGI_RESPONDER: Handler}).run()

In the WebAdmin Console, navigate to PythonVhost > External Apps and create a new External Application. Set the following values:

• Name: MyPythonFCGI
• Address: uds://tmp/lshttpd/mypythonfcgi.sock
• Max Connections: 10
• Initial Request Timeout (secs): 10
• Retry Timeout (secs): 0
• Persistent Connection: Yes
• Connection Keepalive Timeout: 30
• Response Bufferring: No
• Start By Server: Yes
• Command: The path to the Python FCGI app, e.g., /absolutepathto/demoapp.py
• Back Log: 50
• Instances: 10

Navigate to PythonVhost > Contexts and create a new FCGI Context. Set the following values:

• URI: URI path to bind to python FCGI app we created, e.g., /python/
• Fast CGI App: Select the Python external app we just created, [VHost Level] MyPythonFCGI

Restart LiteSpeed and access your new Pythyon FCGI application with the /python/ URL in your PythonVhost virtual host.

LSAPI¶

LiteSpeed SAPI is the easiest and fastest way to run web applications with LiteSpeed Web Server. LiteSpeed supports LSAPI for Python applications through WSGI. WSGI (Web Server Gateway Interface) is a low-level interface between web servers and web applications. It allows Python applications designed for WSGI to be used in a variety of settings. It is important to note that, while most Python applications are WSGI-compatible, not all are.

This guide will explain how to set up LSWS to run Python applications with LWSGI. You should already have a working version of Python installed and virtual hosts set up to run it on.

Compile Python with LSWSGI¶

Download the WSGI LSAPI module from our site here.

Save the module to your server root, /usr/local/lsws. To recompile Python, navigate into the module directory and run the following commands:

cd /usr/local/lsws/wsgi-lsapi-1.6
python ./configure.py
make

Copy the lswsgi file to /usr/local/lsws/fcgi-bin/. (This directory is where all of your LSAPI executables go.)

cp lswsgi /usr/local/lsws/fcgi-bin/

Now your LSWSGI executable is ready for LiteSpeed Web Server.

Set up an External Application¶

This process is the same as with any other LSAPI application, except with a different executable and suffix.

Navigate to the External App tab (WebAdmin console > Configuration > External App) and add an external application. (This can be done at the server or virtual host level.)

Select Type LSAPI App.

Give it a name and a socket. Most importantly, for the Command setting, specify the location of your LSWSGI executable: /usr/local/lsws/fcgi-bin/lswsgi. (You also have to pick values for Max Connections, Initial Request Timeout, and Retry Timeout.)

In the Environment field add the following:

LSAPI_CHILDREN=35

Set Instance to 1.

You now have an LSWSGI external application.

The configuration looks like this:

<extProcessor>
    <type>lsapi</type>
    <name>wsgiapp</name>
    <address>uds://tmp/lshttpd/lswsgi.sock</address>
    <maxConns>35</maxConns>
    <env>LSAPI_CHILDREN=35</env>
    <initTimeout>60</initTimeout>
    <retryTimeout>0</retryTimeout>
    <respBuffer>0</respBuffer>
    <autoStart>1</autoStart>
    <path>/usr/local/lsws/fcgi-bin/lswsgi</path>
    <instances>1</instances>
</extProcessor>

Set up a Script Handler¶

You'll need to create a WSGI script handler to tell LSWS to send .wsgi scripts to your LSWSGI application. Navigate to the Script Handler tab (WebAdmin Console > Configuration > Script Handler) and click Add. (This, also, can be done at the server or virtual host level.)

Stipulate wsgi as the suffix of your WSGI Python apps. Pick Handler Type LiteSpeed SAPI and, for Handler Name, choose the LSWSGI external application you just created. (If you want scripts other than .wsgi to use Python, you can make extra script handlers to handle those scripts.)

Now your LSWS can handle .wsgi scripts and knows where to send them.

Restart and Test¶

Graceful Restart to apply changes.

To test this setup, use the simple hello world script below:

def application(environ, start_response):
  start_response('200 OK', [('Content-Type', 'text/plain')])
  return ['Hello World!n']

Name your file hello.wsgi and save it to /usr/local/lsws/DEFAULT/html. This is the document root for LSWS's default vhost, "Example."

Now, when you point your browser to localhost:8088/hello.wsgi, you will see "Hello World!" displayed.