X-Forwarded-Server

The originating server of a client request.

Fastly reads this header from requests and writes it into requests. It is defined by an external standard.

For VCL services, Fastly will add or append X-Forwarded-Server headers on incoming requests over TLS, as follows:

Fastly's edge cache – if the request protocol is TLS.
Fastly's shield cache – if the origin has a TLS configuration and shielding is enabled.
Even if client connection is TLS, unless the origin connection is over TLS, nothing will be added or appended at the shield.

Examples

Shielding	Request Protocol	Origin Protocol	Client Header	X-Forwarded-Server	Note
No	TLS	TLS	No	cache-nrt6128-NRT	Added at edge
No	Non TLS	TLS	No	null
No	TLS	TLS	Yes	Server1, cache-nrt6146-NRT	Appended
No	Non TLS	TLS	Yes	Server1	Pass-through
No	TLS	Non TLS	No	cache-nrt6128-NRT	Added at edge
No	Non TLS	Non TLS	No	null
No	TLS	Non TLS	Yes	Server1, cache-nrt6146-NRT	Appended
No	Non TLS	Non TLS	Yes	Server1	Pass-through
Yes	TLS	TLS	No	cache-hnd18734-HND, cache-hkg17928-HKG	Added at edge and shield
Yes	Non TLS	TLS	No	cache-hkg17933-HKG	Added at shield
Yes	TLS	TLS	Yes	Server1, cache-nrt6122-NRT, cache-hkg17925-HKG	Added at edge and shield
Yes	Non TLS	TLS	Yes	Server1, cache-hkg17926-HKG	Added at shield
Yes	TLS	Non TLS	No	cache-hnd18723-HND	Added at edge
Yes	Non TLS	Non TLS	No	null
Yes	TLS	Non TLS	Yes	Server1, cache-hnd18746-HND	Added at edge
Yes	Non TLS	Non TLS	Yes	Server1	Pass-through

To set a single value for this header, add the following to vcl_miss and vcl_pass:

set bereq.http.X-Forwarded-Server = server.hostname;