req.backend.is_shield
BOOL, read-only.
Available inall subroutines.
Indicates whether the backend is a Fastly Shield POP.
Shielding directs traffic from the Fastly POPs closest to the end user to the Fastly POP closest to your backend, and onward to your servers. It is therefore possible for a resource to be fetched from a backend that is another Fastly POP. When this is the case, req.backend.is_shield will be true and req.backend.is_origin will be false.
Conversely, if a request is being forwarded from Fastly to a server outside of the Fastly network, req.backend.is_shield will be false and req.backend.is_origin will be true.