flask_client_ip.py

from flask import request
from flask.logging import default_handler

class RequestFormatter(logging.Formatter):
  def format(self, record):
    record.url = request.url
    record.remote_addr = request.remote_addr
    if 'X-Forwarded-For' in request.headers:
      proxy_data = request.headers['X-Forwarded-For']
      ip_list = proxy_data.split(',')
      record.remote_addr = ip_list[0]
    return super(RequestFormatter, self).format(record)

formatter = RequestFormatter(
  '[%(asctime)s] %(remote_addr)s requested %(url)s\n'
  '%(levelname)s in %(module)s: %(message)s'
)

default_handler.setFormatter(formatter)