heroku sqlalchemy config.py

# in your ini file, have this:
# env.use_env_variables = true
# sqlalchemy.url = DATABASE_URL

# then, in your __init__.py file, the first thing you do in your main function is this:

def main(global_config, **settings):
    """ This function returns a Pyramid WSGI application.
    """

    from pyramid.settings import asbool
    if asbool(settings.get('env.use_env_variables', False)):
        from os import getenv
        settings['sqlalchemy.url'] = getenv(settings['sqlalchemy.url'])

    config = Configurator(settings=settings)
    # blah blah blah