Use werkzeugs pre implemented ProxyFix middleware

app/__init__.py

@@ -7,17 +7,6 @@ from flask_sqlalchemy import SQLAlchemy
 import logging
 
 
-class CustomProxyFix(object):
-    def __init__(self, app):
-        self.app = app
-
-    def __call__(self, environ, start_response):
-        scheme = environ.get('HTTP_X_FORWARDED_PROTO')
-        if scheme:
-            environ['wsgi.url_scheme'] = scheme
-        return self.app(environ, start_response)
-
-
 db = SQLAlchemy()
 logger = logging.getLogger(__name__)
 login_manager = LoginManager()
@@ -28,7 +17,6 @@ socketio = SocketIO()
 
 def create_app(config_name):
     app = Flask(__name__)
-    app.wsgi_app = CustomProxyFix(app.wsgi_app)
     app.config.from_object(config[config_name])
 
     config[config_name].init_app(app)

config.py

+from werkzeug.middleware.proxy_fix import ProxyFix
 import os
 import logging
 
@@ -33,7 +34,13 @@ class Config:
 
     @staticmethod
     def init_app(app):
-        pass
+        proxy_fix_kwargs = {
+            'x_for': 1,
+            'x_host': 1,
+            'x_port': 1,
+            'x_proto': 1,
+        }
+        app.wsgi_app = ProxyFix(app.wsgi_app, **proxy_fix_kwargs)
 
 
 class DevelopmentConfig(Config):