AppConfigs

AppConfigs is a small Python module that provides user configuration file management features for Python applications. It is based on the config module of Spyder, the scientific Python development environment.

Installation

AppConfigs can be installed with pip by running:

pip install appconfigs

Requirements

• appdirs : To retrieve the directory that your app should use for storing user data.

Get it started

First, you need to create a new Python file (for example my_conf.py) in which you :

1. define the location where the user configuration files are going to be saved,
2. provide default values for the preferences,
3. setup the main configuration instance that your app will use.

Configuration file setup

Let start with a project structure like the one below with the configuration file my_conf.py located in the module /config .

__init__.py
my_app.py
/config
    | __init__.py
    | my_conf.py

The example below shows the content of the /config/my_conf.py file.

# =============================================================================
# MY_CONF.PY file content
# =============================================================================
from appconfigs.user import UserConfig
from appconfigs.base import get_config_dir

# Define the location where the user configuration files are going to be saved
# (you can use any other location with write permission if you want).
CONFIG_DIR = get_config_dir('my_app_name')

# Provide default values for the preferences.
DEFAULTS = [
    ('main',
        {'pref1': '14px',
         'pref2': 'french'}
     ),
    ('section1',
        {'pref1': 104,
         'pref2': 'blue'}
     )
    ('section2',
        {'pref1': True}
     )
]

# Define the configuration version.
CONF_VERSION = '1.0.0'

# IMPORTANT NOTES:
# 1. When the default value of a current option is changed, a
#    MINOR update in config version is required, e.g. from 3.0.0 to 3.1.0
# 2. When options that are no longer needed in your codebase are removed,
#    or if options are renamed, then a MAJOR update in config
#    version is required, e.g. from 3.0.0 to 4.0.0
# 3. When new options are added, no update in config version is necessary

# Setup the main configuration instance.
try:
    CONF = UserConfig('my_app_name', defaults=DEFAULTS, load=True,
                      version=CONF_VERSION, path=CONFIG_DIR,
                      backup=True, raw_mode=True)
except Exception:
    CONF = UserConfig('my_app_name', defaults=DEFAULTS, load=False,
                      version=CONF_VERSION, path=CONFIG_DIR,
                      backup=True, raw_mode=True)

Using the configuration in application files

We import the main configuration instance where needed to access and manage the preferences of our application. For example, to get the value of pref2 in section1 from the my_app.py file, we would do:

# =============================================================================
# MY_APP.PY file content
# =============================================================================
from .config.my_conf import CONF
my_value = CONF.get('section1', 'pref2')
print(my_value)
>>> 'blue'

Since no user defined value has been set yet for this preference, the default value is returned as expected.

To set a new value for pref2 in section1, we would simply do:

# =============================================================================
# MY_APP.PY file content
# =============================================================================
from .config.my_conf import CONF
CONF.set('section1', 'pref2', 'red')
my_value = CONF.get('section1', 'pref2')
print(my_value)
>>> 'red'

How it works

Versionning

AppConfigs supports multiple configurations at the same time. This feature is mainly used when dealing with diverging configuration between different version of our application. Usually, version naming should follow this pattern:

1. If you want to change the default value of a current option, you need to do a MINOR update in config version, e.g. from 3.0.0 to 3.1.0
2. If you want to remove options that are no longer needed in our codebase, or if you want to rename options, then you need to do a MAJOR update in version, e.g. from 3.0.0 to 4.0.0
3. You don't need to touch this value if you're just adding a new option

Configuration storage

You can define where your application will store it's user data in any directory that you want, provided that the user has read and write access to it.

As shown in the example above, you can also use the utility function get_config_dir from the appconfigs.base module that uses the appdirs package to automatically define the directory that your app should use for storing user data. By default, this directory is defined as :

• On Windows 7 and above :
  • If there is an application author: C:\Users\[USERNAME]\AppData\Local\[APPAUTHOR]\[APPNAME]
  • If there is no application author: C:\Users\[USERNAME]\AppData\Local\[APPNAME]
• On Linux/Unix based OS, the config files are stored at : ~/.config/[APPNAME]
• On macOS, the config files are stored at : /Users/[USERNAME]/Library/Application Support/[APPNAME]

You can also define a custom user config directory for your application through an os environment variable named after that of you application in caps followed by the suffix '_DIR'. When a value for such a variable exists, get_config_dir will return that value instead of the default one. So for the example above, we could define a custom user config directory for our app named my_app_name in the os environment variable named MY_APP_NAME_DIR.