setup [redis](https://pypi.org/project/redis) library with flask using factory pattern or as a flask extension

flask_redis.py

# create redis extension for flask
import redis
from flask import current_app, _app_ctx_stack


class MyRedis(object):
    """Manage Redis Connection"""

    def __init__(self, app=None):
        self.app = app
        if app is not None:
            self.init_app(app)


    def init_app(self, app):
        app.teardown_appcontext(self.teardown)


    def teardown(self, exception):
        pass


    def connect(self):
        return redis.Redis(host=current_app.config['REDIS_HOST'], port=current_app.config['REDIS_PORT'],
                           db=current_app.config['REDIS_DB'])


    @property
    def connection(self):
        ctx = _app_ctx_stack.top
        if ctx is not None:
            if not hasattr(ctx, 'redis_db'):
                ctx.redis_db = self.connect()
            return ctx.redis_db


# now use on app create / factory pattern
# Method: 1
from flask import Flask
import MyRedis

redis = MyRedis()

def create_app(config_name):
    app = Flask(__name__)
    app.config.from_object(config_object)
    redis.init_app(app)
    
    return app

# Method: 2
from flask import Flask
import MyRedis

app = Flask(__name__)
app.config.from_object(config_object)
redis = MyRedis(app)