Last Updated: February 25, 2016

Get correct remote_addr on Heroku with Flask

So I spent far too much time debugging why my session were expiring rapidly on Mighty Spring's stage server that runs on Heroku. I finally dug deep enough with logging to find that remote_addr was returning a different value each time. I created a new Request class that returns the correct remote_addr when running on Heroku.

HerokuRequest gist

from flask import Request


class HerokuRequest(Request):
 """
 `Request` subclass that overrides `remote_addr` with Heroku's
 HTTP_X_FORWARDED_FOR when available.
 """

 @property
 def remote_addr(self):
 """The remote address of the client."""
 fwd = self.environ.get('HTTP_X_FORWARDED_FOR', None)
 if fwd is None:
 return self.environ.get('REMOTE_ADDR')
 # sometimes x-forwarded-for contains multiple addresses,
 # actual client is first, rest are proxy
 fwd = fwd.split(',')[0]
 return fwd


## use HerokuRequest class so we get real IPs
app.request_class = HerokuRequest

#python

#heroku

#flask

#remote_addr