Add ProxyFix to wrap wsgi_app

app.py

@@ -9,6 +9,7 @@ from flask import Flask, redirect, render_template, request, g, flash, url_for
 from flask_login import LoginManager, login_required, login_user, logout_user, \
     UserMixin
 from flask_wtf import CSRFProtect
+from werkzeug.contrib.fixers import ProxyFix
 
 from db import get_db, get_registration_codes, add_registration_code, \
     expire_registration_code, delete_registration_code, get_registered_users, \
@@ -80,6 +81,7 @@ def create_app():
 
 
 app = create_app()
+app.wsgi_app = ProxyFix(app.wsgi_app, num_proxies=1)
 
 log.info("Bound reverse proxy wsgi app")