Configuration

asab.Config

The configuration is provided by Config object which is a singleton. It means that you can access Config from any place of your code, without need of explicit initialisation.

import asab

# Initialize application object and hence the configuration
app = asab.Application()

# Access configuration values anywhere
my_conf_value = asab.Config['section_name']['key1']

Based on ConfigParser

The Config is inherited from Python Standard Library configparser.ConfigParser class. which implements a basic configuration language which provides a structure similar to what’s found in Microsoft Windows INI files.

class asab.config.ConfigParser[source]

Example of the configuration file:

[bitbucket.org]
User = hg

[topsecret.server.com]
Port = 50022
ForwardX11 = no

And this is how you access configuration values:

>>> asab.Config['topsecret.server.com']['ForwardX11']
'no'

Automatic load of configuration

If a configuration file name is specified, the configuration is automatically loaded from a configuration file during initialiation time of Application. The configuration file name can be specified by one of -c command-line argument (1), ASAB_CONFIG environment variable (2) or config [general] config_file default value (3).

./sample_app.py -c ./etc/sample.conf

Including other configuration files

You can specify one or more additional configuration files that are loaded and merged from an main configuration file. It is done by [general] include configuration value. Multiple paths are separated by os.pathsep (: on Unix). The path can be specified as a glob (e.g. use of * and ? wildcard characters), it will be expanded by glob module from Python Standard Library. Included configuration files may not exists, this situation is silently ignored.

[general]
include=./etc/site.conf:./etc/site.d/*.conf

Configuration default values

Config.add_defaults(dictionary)

This is how you can extend configuration default values:

asab.Config.add_defaults(
    {
        'section_name': {
            'key1': 'value',
            'key2': 'another value'
        },
        'other_section': {
            'key3': 'value',
        },
    }
)

Environment variables in configration

Environment variables found in values are automaticall expanded.

[section_name]
persistent_dir=${HOME}/.myapp/

>>> asab.Config['section_name']['persistent_dir']
'/home/user/.myapp/'