Swing

Python's configuration switcher by an environment variable inspired by Common Lisp's envy

Description

Swing is a configuration manager for python app, it uses an environment variable to determine a configuration to use. It makes developer switching configurations between different situations quickly.

Install

pip install swing

Usage

Assuming that you want to use a database while developing, and use another database when running it in production enviroment, using swing, it's simple, only one step:

Just define your configurations in some place of your code, eg. settings.py:

from swing import ConfigBase

class DevelopmentConfig(ConfigBase):

    __confname__ = "development"
    
    DEBUG = True
    DB_CONNECTION = "mysql://username:password@ip:port/dev_db"

class ProductionConfig(ConfigBase):

    __confname__ = "production"

    DEBUG = False
    DB_CONNECTION = "mysql://username:password@ip:port/production_db"

And you can access the configurations where you need now, eg. app.py:

import settings # this makes the configuration known by Swing
from swing import config
print config.DB_CONNECTION

Now, you can now set the Envrioment Variable APP_ENV's value to "development", and swing will use the "development" configuration.

eg. in unix-like systems, you will get:

$ APP_ENV=development python app.py
mysql://username:password@ip:port/dev_db

while with APP_ENV=production:

$ APP_ENV=production python app.py
mysql://username:password@ip:port/production_db

that's swing :)

Configurations

General

You have to subclass the class ConfigBase to declare a configuration, and the configuration's name can be defined through the class's __confname__ attribute. If you do not set the __confname__, Swing will take the configuarion as the default configuration.

Then you can control which configuration to use through the Enviroment Variable, and access the attributes of the configuration through config

The Enviroment Variable

By default, the Environment Variable Swing used to control which configuration to use is APP_ENV. You can change it through set_env_var(the_new_enviroment_var).

get_env_var() to get current Enviroment Variable

Common Configurations

You can define some common configuration sharing by multiple configurations by just following the inheritance of python class, eg:

from swing import ConfigBase
class CommonConfig(ConfigBase):

    SOME_COMMEN_SETTING = "some commen setting"

class DevelopmentConfig(CommonConfig):

    __confname__ = "development"
    
    DEBUG = True
    DB_CONNECTION = "mysql://username:password@ip:port/dev_db"

class ProductionConfig(CommonConfig):

    __confname__ = "production"

    DEBUG = False
    DB_CONNECTION = "mysql://username:password@ip:port/production_db"

API

All the api available throgh swing.API

ConfigBase

class ConfigBase

The super class used to define a configuration

• __confname__ - the configuration name, "default" if not declared

config

config

This object points to the current configuration, you can access to the configuraton by accessing the object's attribute

switch_config

def switch_config(confname)

switch to a the configuration the confname points

• confname - the configuration the you want to use

refresh_config

def refresh_config()

refresh the current configuration according to the current Eviroment Variable

clear_config

def clear_config()

clear all configuration that defined yet

set_env_var

def set_env_var(env_var)

set the Enviroment Variable that swing used to determine which configuration to use

• env_var - the Enviroment Variable to use

get_env_var

def get_env_var()

get the current Enviroment Variable

Author

• Monklof (monklof@gmail.com)

License

MIT