Environment-specific settings for python 2 modules

environment-specific-settings.py

# Environment-specific settings for python 2 modules

# This code placed in __init__.py will allow a module to maintain
# environment-specific settings in files located in a settings folder
# within the module.
#
# Example:
#
# ├── mymodule.py
# ├── __init__.py
# └── settings
#     ├── __init__.py          <== code below goes here
#     ├── mymodule.default.py
#     ├── mymodule.test.py
#     └── mymodule.prod.py
#
# Use:
#
# mymodule.default.py
#
# MY_SETTING = "Hello"
#
# mymodule.test.py
#
# MY_SETTING = "Goodbye"
#
# mymodule.py
#
# import settings
# print settings.MY_SETTING
#
# The above will print "Hello" when the environment is set to
# 'test' and "Goodbye" when it is set to 'dev' or is not set.

import os
import inspect

# The code expects the environment name in an environment var
# named 'ENV' which can be changed here. The value of this
# var will be used to complete settings file names below. It
# can be any string, and the default is 'dev'
ENV = os.environ.get('ENV', 'dev')

# Determine the file that imported us
caller = inspect.currentframe().f_back.f_code.co_filename
caller = os.path.basename(caller).replace('.py','')

# Collect objects here
__namespace = {}

# Load the defaults for the caller. The defaults are expected
# to be in settings/<mod name>.default.py
__mod_dir = os.path.dirname(__file__)
__mod_name = '{}.default.py'.format(caller)
__mod_file = '{}/{}'.format(__mod_dir, __mod_name)

try:
    execfile(__mod_file, __namespace)
except Exception as e:
    raise Exception("Failed to load default settings from: '{}'.".format(__mod_file), e)

# Now load the env-specific settings for the caller if present
__mod_name = '{}.{}.py'.format(caller, ENV)
__mod_file = '{}/{}'.format(__mod_dir, __mod_name)
if os.path.isfile(__mod_file):
    try:
        execfile(__mod_file, __namespace)
    except Exception as e:
        raise Exception("Failed to load settings from: '{}'.".format(__mod_file), e)

# Update the namespace
globals().update(__namespace)