Replace the Real IP in flask's logger when flask is behind of nginx or proxy.

flask_log_the_right_remote_ip.py

@app.before_request
def before_request_func():
    from flask import redirect, request
    real_ip = request.headers.get("X-Real-IP", "")
    if real_ip and "127.0.0.1" == request.environ['REMOTE_ADDR']:
        request.environ['REMOTE_ADDR'] = real_ip
    #print("before_request executing!")

The origional logger function is came from werkzeug's log_request functin in WSGIRequestHandler
https://github.com/pallets/werkzeug/blob/726eaa28593d859548da3477859c914732f012ef/src/werkzeug/serving.py#L414