Configuration

A common pattern is to store configuration values in the environment. Quart supports this via from_prefixed_env() which can be used to load environment variables into the configuration. Only environment variables starting with the prefix, default QUART_ will be loaded. For example if the environment variable QUART_TESTING=true is set then,

app = Quart(__name__)
app.config.from_prefixed_env()
assert app.config["TESTING"] is True

Another common pattern for configuration loading is to use class inheritance to define common settings with production and development overrides, for example,

class Config:
    DEBUG = False
    TESTING = False
    SECRET_KEY = 'secret'

class Development(Config):
    DEBUG = True

class Production(Config):
    SECRET_KEY = 'an actually secret key'

This can then be loaded in say a create_app function, for example:

def create_app(mode='Development'):
    """In production create as app = create_app('Production')"""
    app = Quart(__name__)
    app.config.from_object(f"config.{mode}")
    return app

Custom configuration class

The config_class can be set to a custom class, however it must be changed before the app is initialised as the make_config() is called on construction.

Instance folders

An instance folder is a deployment specific location to store files and configuration settings. As opposed to loading files relative to the app root path open_resource() you can load files relative to an instance path open_instance_resource() including the configuration. To load the configuration from this folder, instead of relative to the app root path simply provide the instance_relative_config argument as True when initialising the app app = Quart(__name__, instance_relative_config=True).

The instance path can be specified when initialising the app, or found automatically if it exists. The search locations are:

/app.py
/instance/

or if the app has been installed:

$PREFIX/var/app-instance/