Tag Archives: python

Simple configuration file parser (python)

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Python’s ConfigParser works well for INI files but what about config files that are simple key/value options? For example, ConfigParser will not work with files like this:


#Example configuration file
#Foo Bar-er v1.0
foo_dir="/var/lib/foo"
bar_dir="/var/lib/bar"
foo_all_the_bars="1"
bar_all_the_foos = "yes, do it"

Granted, the example above is a poorly written config file however I’m using it as an example to demonstrate the flexibility of configuration parser. So here’s the code:


# SimpleConfigParser
# Inspired by:
# http://www.decalage.info/fr/python/configparser
class SimpleConfigParser():

    def __init__(self, comment_char = '#', option_char = '=', allow_duplicates = False, strip_quotes = True):
        self.comment_char = comment_char
        self.option_char = option_char
        self.allow_duplicates = allow_duplicates
        self.strip_quotes = True

    def parse_config(self, filename):
        self.options = {}
        config_file = open(filename)
        for line in config_file:
            if self.comment_char in line:
                line, comment = line.split(self.comment_char, 1)
            if self.option_char in line:
                option, value = line.split(self.option_char, 1)
                option = option.strip()
                value = value.strip()
                value = value.strip('"\'')
                if self.allow_duplicates:
                    if option in self.options:
                        if not type(self.options[option]) == list:
                            old_value = self.options[option]
                            self.options[option] = [value] + [old_value]
                        else:
                            self.options[option] += [value]
                    else:
                        self.options[option] = value
                else:
                    self.options[option] = value
        config_file.close()
        return self.options

And here’s an example of how you’d use this (assuming you saved the code in a file named ‘simpleconfig.py’ and you saved the example config as ‘example.cfg’):


Python 2.7.3 (default, Aug 1 2012, 05:14:39)
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from simpleconfig import SimpleConfigParser
>>> scp = SimpleConfigParser()
>>> scp.parse_config('example.cfg')
{'bar_dir': '/var/lib/bar', 'foo_all_the_bars': '1', 'foo_dir': '/var/lib/foo', 'bar_all_the_foos': 'yes, do it'}
>>>

Also, if you have a config file that has duplicate “options” (nagios.cfg comes to mind), you can do the following:

Python 2.7.3 (default, Aug  1 2012, 05:14:39) 
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from simpleconfig import SimpleConfigParser
>>> scp = SimpleConfigParser(allow_duplicates = True)
>>> nagios_config = scp.parse_config('/etc/nagios3/nagios.cfg')
>>> nagios_config['cfg_dir']
['/etc/nagios3/conf.d', '/etc/nagios-plugins/config']
>>>

Instead of a key/value pair, you’ll get a key with a list as it’s value for each identically named configuration option.

jqueryFileTree connector script for python cgi

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If you use jquery and haven’t messed with the jqueryFileTree plugin, I’d highly recommend you do so. It’s pretty neat, and there are connector scripts already written in various languages for use with this plugin. However, there wasn’t one for python cgi (there was one for django however). So, I wrote my own! Try it out:

#!/usr/bin/python
# jqueryFileTree connector script for python cgi 
# Version: 1.0 / 10 August 2010
# Author: Charles Hamilton / musashi@nefaria.com
# Released under the GNU GPLv3
# Modifications and improvements are welcome

import os, cgi, cgitb, urllib, re
cgitb.enable()
form = cgi.FieldStorage()

print 'Content-Type: text/html\n\n'
print '<ul class="jqueryFileTree" style="display: none;">'

path = urllib.unquote(form['dir'].value)

dirs = []
files = []

filelist = sorted(os.listdir(path))

for object in filelist:
    if os.path.isfile(path + '/' + object):
       ext = os.path.splitext(object)
        files.append('<li class="file ext_' + re.sub('\.', '', ext[1]) + '"><a href="#" rel="'+ path + object + '">'+ object + '</a></li>')
    elif os.path.isdir(path + '/' + object):
        dirs.append('<li class="directory collapsed"><a href="#" rel="'+ path + object +'/">' + object + '</a></li>')

for d in dirs:
    print d

for f in files:
    print f
print '</ul>'

Python + Reportlab: example #1

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So I’ve been using reportlab lately and I have to say, it’s pretty neat. This post will (hopefully) be the first of many to follow. It’s just a simple example that shows how to take input from a web form and insert it into a PDF. First, the code:

 1 #!/usr/bin/python
 2
 3 import cgi, sys
 4
 5 form = cgi.FieldStorage()
 6
 7 if not "name" in form:
 8     print """Content-Type: text/html\n\n
 9 <html>
10     <head>
11         <title>Reportlab Example</title>
12     </head>
13     <body>
14         <form action="index2.cgi" method="post" enctype="multipart/form-data">
15             <fieldset>
16                 <legend>Personal Info:</legend>
17                 Name: <input type="text" name="name"><br />
18                 Photo: <input type="file" name="photo"><br />
19                 <input type="submit">
20             </fieldset>
21         </form>
22     </body>
23 </head>"""
24
25 else:
26
27     from reportlab.platypus import *
28     from reportlab.lib.styles import getSampleStyleSheet
29     from reportlab.lib.units import inch
30     from reportlab.lib import colors
31     doc = SimpleDocTemplate(sys.stdout)
32     styles = getSampleStyleSheet()
33     content = []
34     
35     if form['photo'].filename:
36         image = Image(form['photo'].file)
37         image.drawHeight = 2*inch*image.drawHeight / image.drawWidth
38         image.drawWidth = 2*inch
39
40     if form['name'].value:
41         text1 = Paragraph(form['name'].value, styles['Heading1'])
42         text2 = Paragraph(form['name'].value, styles['Heading2'])
43         text3 = Paragraph(form['name'].value, styles['Heading3'])
44
45     content.append(text1)
46     content.append(text2)
47     content.append(text3)
48     content.append(image)
49     print "Content-Type: application/pdf"
50     print "Content-Disposition: attachment; filename=example.pdf\n\n"
51     doc.build(content)

Now the explanation:

Lines #1 – #5 handle specifying the interpreter, importing modules, and initializing the “FieldStorage” dictionary (as the variable ‘form’).

 1 #!/usr/bin/python
 2
 3 import cgi, sys
 4
 5 form = cgi.FieldStorage()

Line #7 tests whether the form has been submitted by checking to see if the ‘name’ field has been filled out. There’s many better ways to test for form submission, but for the purposes of our example, this will work just fine.

 7 if not "name" in form:

Lines #8 – #23 print the form

 8     print """Content-Type: text/html\n\n
 9 <html>
10     <head>
11         <title>Reportlab Example</title>
12     </head>
13     <body>
14         <form action="index2.cgi" method="post" enctype="multipart/form-data">
15             <fieldset>
16                 <legend>Personal Info:</legend>
17                 Name: <input type="text" name="name"><br />
18                 Photo: <input type="file" name="photo"><br />
19                 <input type="submit">
20             </fieldset>
21         </form>
22     </body>
23 </head>"""

Lines #26 – #29 import some more modules (i.e., reportlab related stuff).

26     from reportlab.platypus import *
27     from reportlab.lib.styles import getSampleStyleSheet
28     from reportlab.lib.units import inch
29     from reportlab.lib import colors

Now line #30 is important, this is where we decide where we want to write the output. We can either save the output to a file, or we can dump it to stdout (i.e., back to the web browser). In this example, we’re going to send the output back to the web browser.

30     doc = SimpleDocTemplate(sys.stdout)

Line #31 handles getting the style sheet that we’re going to use to format our text.

31     styles = getSampleStyleSheet()

In line #32, we initialize the ‘content’ dictionary — this is where we’re going to keep the elements of our PDF until we’re ready to write it to stdout.

32     content = []

In lines #34 – #37, we test for the ‘photo’ field — if it has been submitted, we create an Image object out of it. We’re assuming that the user is going to submit a photo, but in reality, the user could submit anything so some further “hardening” of this form would be required in order to ensure that the only things that actually get submitted are image files.

34     if form['photo'].filename:
35         image = Image(form['photo'].file)
36         image.drawHeight = 2*inch*image.drawHeight / image.drawWidth
37         image.drawWidth = 2*inch

Lines #39 – #42 test to see if the ‘name’ field has been submitted; if it has, it creates some text objects to insert into our PDF.

39     if form['name'].value:
40         text1 = Paragraph(form['name'].value, styles['Heading1'])
41         text2 = Paragraph(form['name'].value, styles['Heading2'])
42         text3 = Paragraph(form['name'].value, styles['Heading3'])

Lines #44 – #47 append all the objects that we want to appear in our PDF, to the ‘content’ dictionary we created earlier.

44     content.append(text1)
45     content.append(text2)
46     content.append(text3)
47     content.append(image)

Lines #48 – #49 send the appropriate headers to the web browser, before we send our completed PDF file.

48     print "Content-Type: application/pdf"
49     print "Content-Disposition: attachment; filename=example.pdf\n\n"

And finally, line #50 builds our PDF and sends the output to stdout.

50     doc.build(content)

Test it out; you should end up with a PDF that looks something like this:

reportlab_example1_img1

Of course, this example doesn’t even scratch the surface of what you can do with reportlab. Hopefully I’ll post some more examples later on :-)