Portable/reusable flask app skeleton

I have a lot of Flask apps running in the background on my home server to do various tasks (home wiki, some CRM stuff, etc) and I end up making the same structure over and over so I figured I would simplify the process and make a repo with just the skeleton of an app.

A few benefits:

  1. as long as you use relative imports . and .. (eg from .. import app) your web application is name agnostic.
  2. The flask application instance of Flask() can be accessed from anywhere in the web application without a risk of circular import problems.
  3. It’s entirely possible to copy and paste web application modules (eg models) into another web application and it will mostly just work (baring configuration needs).


import logging
import sys
from flask import Flask

app:Flask = Flask(__name__)
log:logging.Logger = None

def create_app(config=None)->Flask:
    global app, log
    from . import conf

    log = logging.getLogger(__name__)
    fmt = logging.Formatter(app.config['APP_LOGGING_FMT'])
    hndl = app.config['APP_LOGGING_HANDLER']  # type: logging.Handler
    log.propagate = False
    log.handlers.clear() # This removes flask's default handler
    log.debug(f"{__name__} loading components")

    from . import lib
    from . import models
    from . import views
    from . import settings

    return app


This is the __init__.py file in the base of the web app. To use it with flask you would do something like this on the commandline

#>set FLASK_RUN_PORT=1234
#>set FLASK_APP = "webapp:create_app()"
#>set FLASK_ENV = development
#>python -m flask run
#>flask run

The FLASK_APP environment variable is documented here https://flask.palletsprojects.com/en/1.1.x/cli/#application-discovery and it’s pretty straight forward module:function_name() where function_name is defined in module/__init__.py

The reason for having the imports for lib models views settings in create_app is to prevent a circular import and allow sub modules like views to do from .. import app to access the Flask application instance.