Python | Reading .ini Configuration Files

This article aims to read configuration files written in the common .ini configuration file format. The configparser module can be used to read configuration files.

Code #1 : Configuration File

abc.ini

; Sample configuration file
[installation]
library = %(prefix)s/lib
include = %(prefix)s/include
bin = %(prefix)s/bin
prefix = /usr/local

# Setting related to debug configuration
[debug]
pid-file = /tmp/spam.pid
show_warnings = False
log_errors = true
[server]
nworkers: 32
port: 8080
root = /www/root
signature:

Code #2 : Reading the file and extracting values.

from configparser import ConfigParser

configur = ConfigParser()
print (configur.read('config.ini'))

print ("Sections : ", configur.sections())
print ("Installation Library : ", configur.get('installation','library'))
print ("Log Errors debugged ? : ", configur.getboolean('debug','log_errors'))
print ("Port Server : ", configur.getint('server','port'))
print ("Worker Server : ", configur.getint('server','nworkers'))

Output :

['config.ini']
Sections : ['installation', 'debug', 'server']
Installation Library : '/usr/local/lib'
Log Errors debugged ? : True
Port Server : 8080
Worker Server : 32

One can also modify the configuration and write it back to a file using the cfg.write() method.

Code #3 :

configur.set('server','port','9000')
configur.set('debug','log_errors','False')

import sys
configur.write(sys.stdout)

Output :

[installation]
library = %(prefix)s/lib
include = %(prefix)s/include
bin = %(prefix)s/bin
prefix = /usr/local

[debug]
log_errors = False
show_warnings = False

[server]
port = 9000
nworkers = 32
pid-file = /tmp/spam.pid
root = /www/root

• Configuration files are well suited to specify configuration data to your program. Within each config file, values are grouped into different sections (e.g., “installation”, “debug” and “server”).
• Each section then has a specific value for various variables in that section. For the same purpose, there are some prominent differences between a config file and using a Python source file.
• First, the syntax is much more permissive and “sloppy.”

Names used in a config file are also assumed to be case-insensitive as shown in the code below –

configur.get('installation','PREFIX')

configur.get('installation','prefix')

Output :

'/usr/local'
'/usr/local'

When parsing values, methods such as getboolean() look for any reasonable value. For example, these are all equivalent.

log_errors = true
log_errors = TRUE
log_errors = Yes
log_errors = 1

The most noteworthy contrast between a config record and Python code is that, in contrast to scripts, configuration files are not executed in a top-down way. Rather, the file is read completely. On the off chance that variable substitutions are made, they are done later after the fact. For instance, it doesn’t make a difference that the prefix variable is allocated after different variables that happen to utilize it.

[installation]
library = %(prefix)s/lib
include = %(prefix)s/include
bin = %(prefix)s/bin
prefix = /usr/local

Multiple configuration files can be read together and their results can be merged into a single configuration using ConfigParser, which makes it so special to use.

Example – A user made their own configuration file that looks as.

; ~/.config.ini
[installation]
prefix = /Users/beazley/test
[debug]
log_errors = False

This file can be merged with the previous configuration by reading it separately

Code #4 :

import os

# Previously read configuration
print (configur.get('installation', 'prefix'))

# Merge in user-specific configuration
print (configur.read(os.path.expanduser('~/.config.ini')))
print (configur.get('installation', 'prefix'))
print (configur.get('installation', 'library'))

print (configur.getboolean('debug', 'log_errors'))

Output :

'/usr/local' 
['/Users/HP/.config.ini']
'/Users/HP/test'
'/Users/HP/test/lib'
False