Flask-Env

Easily set Flask settings from environment variables.

The reason for using flask-env is to be able to follow the 12-factor app suggestions for configuring your application.

With flask-env you can define your default configuration options in code and very easily override via environment variables.

Installation

pip install Flask-Env

Usage

With flask-env you will define your configuration as an object and load it into your Flask application via app.config.from_object method.

Python 2

from flask import Flask
from flask_env import MetaFlaskEnv


class Configuration(object):
    __metaclass__ = MetaFlaskEnv

    DEBUG = False
    PORT = 5000


app = Flask(__name__)
app.config.from_object(Configuration)

Python 3

from flask import Flask
from flask_env import MetaFlaskEnv


class Configuration(metaclass=MetaFlaskEnv):
    DEBUG = False
    PORT = 5000


app = Flask(__name__)
app.config.from_object(Configuration)

Overriding environment variables

# Export environment variable for shell session
export DEBUG=true

# Set explicitly for a specific command execution
PORT=8000 python app.py

Configuring flask-env

flask-env offers two configuration options to determine how/which environment variables are loaded.

ENV_PREFIX

Only consider environment variables that start with this prefix. The prefix will be removed from the environment variable name when setting in the configuration. (default: '', example: ENV_PREFIX = 'MYAPP_')

ENV_LOAD_ALL

Whether or not to load all environment variables for the configuration object. When False only settings predefined on the configuration object are loaded, all others are ignored. When True all environment variables defined in os.environ will get loaded into your configuration object. (default False)

Setting configuration values

You can set the flask-env configuration settings directly on your Flask configuration object.

from flask_env import MetaFlaskEnv


class Configuration(metaclass=MetaFlaskEnv):
    ENV_PREFIX = 'MYAPP_'
    ENV_LOAD_ALL = False