import logging

from logging.handlers import RotatingFileHandler

from flask import Flask

app = Flask(__name__)

@app.route('/')

def foo():

    app.logger.warning('A warning occurred (%d apples)', 42)

    app.logger.error('An error occurred')

    app.logger.info('Info')

    return "foo"

if __name__ == '__main__':

    handler = RotatingFileHandler('foo.log', maxBytes=10000, backupCount=1)

    handler.setLevel(logging.INFO)

    app.logger.addHandler(handler)

    app.run()