creating python daemon ?

Diez B. Roggisch deets at web.de
Wed Sep 22 11:20:59 CEST 2010


vineet daniel <vineetdaniel at gmail.com> writes:

> On Sep 21, 9:47 pm, de... at web.de (Diez B. Roggisch) wrote:
>> vineet daniel <vineetdan... at gmail.com> writes:
>> > Hi
>>
>> > I have succesfully created daemon with python script and as next step
>> > I am trying to give input to that python script daemon from Apache
>> > Logs....here I have got stuck and I have even checked IRC python
>> > channel for solution. Apache is able to call the file but fails to
>> > execute it properly and I get this error continuosly :
>>
>> > piped log program '/var/www/html/test.py' failed unexpectedly
>>
>> > How do I rectify the above error and make adjustment to the code so
>> > that it takes input from apache.
>>
>> > code that I am using is as follows :
>>
>> > #! /usr/bin/env python
>> > import sys,os
>> > pid = os.fork()
>> > os.chdir("/var/www/html/")
>> > os.setsid()
>> > os.umask(0)
>> > #this line will read apache log in real time as redirected from the
>> > CustomLog directive of Apache.
>> > log = sys.stdin.readlines()
>> > f = open('/var/www/logmongo.txt','a') # append log to this text file
>> > f.write(log)
>>
>> > I'd appreciate if anybody could share the code that they used for
>> > daemon or used with Apache CustomLog directive.
>>
>> The above code looks errornous - you don't check for the return-value of
>> PID & take appropriate action. Like
>>
>> There is a daemonization recipe on active-state, which works nicely for
>> me.
>>
>> http://code.activestate.com/recipes/278731-creating-a-daemon-the-pyth...
>>
>> Diez
>
> Hi Diez
>
> Thanks for pointing that out.
> Ever tried giving input to such python daemons from a dynamic source
> like Apache logs which get generated in real time. I want apache to
> directly write to this python daemon which in turn will process the
> logs the way I want. Any help will help me immensely.

I don't understand the question. How is that input produced? How shall
the two processes interact? Through some logfile one writes, the other
reads? Through RPC-mechanisms? Sockets? Pipes? 

The fact that process B is a daemon or not has nothing to do with this
whatsoever, btw.

Diez



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