werkzeug.middleware.proxy_fix

This module provides a middleware that adjusts the WSGI environ based on X-Forwarded- headers that proxies in front of an application may set.

When an application is running behind a proxy server, WSGI may see the request as coming from that server rather than the real client. Proxies set various headers to track where the request actually came from.

This middleware should only be used if the application is actually behind such a proxy, and should be configured with the number of proxies that are chained in front of it. Not all proxies set all the headers. Since incoming headers can be faked, you must set how many proxies are setting each header so the middleware knows what to trust.