__init__.py

import importlib
import os
import sys

from flask import Flask


__all__ = ['app', 'settings']


class Settings(object):
    """A class to allow dynamically generating & encapsulating app
    settings. When the module is imported, this object looks for an
    environment variable called "SETTINGS_MODULE". If it doesn't find it,
    it will default to using settings_module.vagrant.
    """
    def __init__(self):
        _settings = os.environ.get('SETTINGS_MODULE',
                                   'myproject.settings_modules.vagrant')
        self._settings = importlib.import_module(_settings)
        for attr, val in self._settings.__dict__.items():
            setattr(self, attr, val)

    def __getattr__(self, name, default=None):
        attr = getattr(self._settings, name, default)

        if attr is None and default is None:
            raise ImportError("Module '%s' has no attribute %s." %
                              (self._settings.__name__, name))

        return attr

    def db_uri(self, db='myproject'):
        kwargs = self.DATABASES[db]
        return '{SCHEME}{USER}:{PASSWORD}@{HOST}/{NAME}'.format(**kwargs)


settings = Settings()
sys.modules['myproject.settings'] = settings
app = Flask('myproject')
app.config.from_object(settings)

Hi I read your comment on HN: I would recommend using a function to configure you app object with. This would allow you to inject and overload the configuration process with deployment-specific environment variables. Maybe something along these lines:

import os

from flask import Flask

# ...


def setup_app():
    app = Flask(__name__)
    app.config.from_object('myapp.config')

    if 'MYAPP_CONFIG' in os.environ:
        app.config.from_envvar('MYAPP_CONFIG')

   # do some other things...

    return app

What does that get me that my original solution doesn't?