Setting up config variables in a Flask app

Here is how I set up configuration files in my Flask app.

app.config object

my_app/config.py:

import os
basedir = os.path.abspath(os.path.dirname(__file__))

class Config(object):
    SQLALCHEMY_DATABASE_URI = 'sqlite:///test_whatever.db'
    SQLALCHEMY_TRACK_MODIFICATIONS = False

class ProductionConfig(Config):
    SQLALCHEMY_DATABASE_URI = 'sqlite:///prod_whatever.db'
    SQLALCHEMY_TRACK_MODIFICATIONS = False

class DevelopmentConfig(Config):
    SQLALCHEMY_DATABASE_URI = 'sqlite:///test_whatever.db'
    SQLALCHEMY_TRACK_MODIFICATIONS = False

my_app/app/app.py:

from flask import Flask, send_from_directory
from config import ProductionConfig, Config, DevelopmentConfig
from app.models import db
import os

def create_app():
    app = Flask(__name__)

    # Here, you refer to the DevelopmentConfig as a string
    app.config.from_object('config.DevelopmentConfig')

    # more init stuff here, blueprints, etc

    db.init_app(app)
    return app

environment variables

Sometimes you might want to load environment variables instead. For example to avoid the whole circular dependency issue when initializing blueprints within your app.

Here's how I initialized and read environment variables:

1. in venv pip install python-dotenv
2. include .env file at application root. Format should be MY_VAR='whatever'

in my_app/app/routes.py (or whatever .py file):

from dotenv import load_dotenv

you can initialize and refer explicitly to the environment vars:

load_dotenv()  # take environment variables
api_key=os.getenv('MY_API_KEY') #refer to environment variable
print('api key: ', api_key)

openai is a special case, they don't want it passed in explicitly. This worked for me:

load_dotenv()  # take environment variables
openai = OpenAI()

You can find a more exhaustive guide to configuration here. Hopefully this will get you started.