How to debug/log wsgi python app?
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I tried this:

#!/usr/bin/python    

from wsgiref.simple_server import make_server
from cgi import parse_qs, escape
import logging
import os
import sys

html = """
<html>
<body>
   <form method="post" action="parsing_post.wsgi">
      <p>
         Age: <input type="text" name="age">
         </p>
      <p>
         Hobbies:
         <input name="hobbies" type="checkbox" value="software"> Software
         <input name="hobbies" type="checkbox" value="tunning"> Auto Tunning
         </p>
      <p>
         <input type="submit" value="Submit">
         </p>
      </form>
   <p>
      Age: %s<br>
      Hobbies: %s
      </p>
   </body>
</html>
"""

def application(environ, start_response):

   # the environment variable CONTENT_LENGTH may be empty or missing
   try:
      request_body_size = int(environ.get('CONTENT_LENGTH', 0))
   except (ValueError):
      request_body_size = 0

   # When the method is POST the query string will be sent
   # in the HTTP request body which is passed by the WSGI server
   # in the file like wsgi.input environment variable.
   logger = logging.getLogger(__name__)
   request_body = environ['wsgi.input'].read(request_body_size)
   d = parse_qs(request_body)


   age = d.get('age', [''])[0] # Returns the first age value.
   hobbies = d.get('hobbies', []) # Returns a list of hobbies.

   # Always escape user input to avoid script injection
   age = escape(age)
   hobbies = [escape(hobby) for hobby in hobbies]

   response_body = html % (age or 'Empty',
               ', '.join(hobbies or ['No Hobbies']))

   status = '200 OK'

   response_headers = [('Content-Type', 'text/html'),
                  ('Content-Length', str(len(response_body)))]
   start_response(status, response_headers)

   return [response_body]

But i don't know where it logs. I'm trying to display/log the value on webpage or in a file /var/log/apache2/myapp.log

What's the best way to do this?

Any answer will be highly appreciated.

Nada answered 3/7, 2012 at 11:20 Comment(1)
See code.google.com/p/modwsgi/wiki/DebuggingTechniquesParacelsus
D
7

Note that the above code won't actually produce any log whatsoever since your not calling any of the logger.log() variants - but I guess that's not the point.

If you're running your code with apache/mod_wsgi, the simplest solution is to configure your logger(s) to log to sys.stderr using a StreamHandler (cf http://docs.python.org/howto/logging.html#configuring-logging), and define the error log path, name and level in your apache conf (beware, the default apache behaviour is to only log "error level" message).

Derry answered 3/7, 2012 at 11:34 Comment(1)
And code.google.com/p/modwsgi/wiki/DebuggingTechniques tells you how to raise the log level.Paracelsus

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