confget 2.3.0

Parse configuration files and extract values from them

confget - parse configuration files

The confget library parses configuration files (currently INI-style files and CGI QUERY_STRING environment variable) and allows a program to use the values defined in them. It provides various options for selecting the variable names and values to return and the configuration file sections to fetch them from.

The confget library may also be used as a command-line tool with the same interface as the C implementation.

The confget library is fully typed.

Specifying configuration values for the backends

The confget.defs module defines the Config class that is used to control the behavior of the various confget backends. Its main purpose is to specify the filename and, optionally, the section name for INI-style files, but other backends may use its fields in different ways.

A Config object is created using the following parameters:

• a list of variable names to query (may be empty)
• filename (str, optional): the name of the file to open
• section (str, default ""): the name of the section within the file
• section_specified (bool, default false): if section is an empty string, only fetch variables from the unnamed section at the start of the file instead of defaulting to the first section in the file

Parsing INI-style configuration files

The confget library's "ini" backend parses an INI-style configuration file. Its read_file() method parses the file and returns a dictionary of sections and the variables and their values within them:

import confget

cfg = confget.Config([], filename='config.ini')
ini = confget.BACKENDS['ini'](cfg)
data = ini.read_file()
print('Section names: {names}'.format(names=sorted(data.keys())))
print(data['server']['address'])

Letting variables in a section override the default ones

In some cases it is useful to have default values before the first named section in a file and then override some values in various sections. This may be useful for e.g. host-specific configuration kept in a section with the same name as the host.

The format module in the confget library allows, among other filtering modes, to get the list of variables with a section overriding the default ones:

from confget import backend, format

cfg = format.FormatConfig(['foo'], filename='config.ini', section='first',
                          section_override=True)
ini = backend.BACKENDS['ini'](cfg)
data = ini.read_file()
res = format.filter_vars(cfg, data)
assert len(res) == 1, repr(res)
print(res[0].output_full)

cfg = format.FormatConfig(['foo'], filename='config.ini', section='second',
                          section_override=True)
ini = backend.BACKENDS['ini'](cfg)
data = ini.read_file()
res = format.filter_vars(cfg, data)
assert len(res) == 1, repr(res)
print(res[0].output_full)

See the documentation of the FormatConfig class and the filter_vars() function in the confget.format module for more information and for a list of the various other filtering modes, all supported when the library is used as a command-line tool.

Comments: Peter Pentchev [e-mail]