Heroku support

Flask-AppConfig supports configuring a number of services through HerokuConfig:

from flask_appconfig import HerokuConfig

def create_app(configfile=None):
    app = Flask('myapp')
    HerokuConfig(app, configfile)
    return app

Works like the example above, but environment variables set by various Heroku addons will be parsed as json and converted to configuration variables accordingly. Forexample, when enabling Mailgun, the configuration of Flask-Mail will be automatically be set correctly.

Using “ENV-only”

If you only want to use the environment-parsing functions of Flask-AppConfig, the appropriate functions are exposed:

from flask_appconfig.heroku import from_heroku_envvars
from flask_appconfig.env import from_envvars

# from environment variables. note that you need to set the prefix, as
# no auto-detection can be done without an app object
from_envvars(app.config, prefix=app.name.upper() + '_')

# also possible: parse heroku configuration values
# any dict-like object will do as the first parameter
from_heroku_envvars(app.config)

Installation

Via PyPI:

$ pip install flask-appconfig

Requires Python 2.7.

flask utility

If you want to get started quickly without thinking a lot about writing a run script, the flask utility supports the create_app/factory pattern:

$ flask --app=myapp dev

This will import a module myapp, and call myapp.run(debug=True).

Other options can come in handy as well:

$ flask --app=myapp dev -S -p 8000

Runs the app on port 8080, with SSL enabled. You can also set the FLASK_APP environment variable or set FLASK_APP inside .env and omit the --app parameter.

Note that the flask utility is subject to change, as it will conflict with the CLI functionality of Flask 1.0. The API is currently kept close, but it will see changes once Flask 1.0 is released.

Thoughts on Configuration

There is a lot of ways to configure a Flask application and often times, less-than-optimal ones are chosen in a hurry.

This extension aims to do three things:

1. Set a “standard” of doing configuration that is flexible and in-line with the official docs and (what I consider) good practices.

2. Make it as convenient as possible to provide these configuration methods in an application.

3. Auto-configure on Heroku as much as possible without sacrificing 1. and 2.

12factor.net seems to capture a good amount of good thoughts on the issue and Flask-Appconfig should aid you in writing an application that follows the principles laid out there.

Development

Flask-AppConfig is under “conceptional development”. The API or semantics may change in the future.

Send pull requests for more Heroku-apps to be supported. Send feedback via mail.

Changelog

Backwards-incompatible changes, as they were introduced: