fastly.try_select_shield
Available inall subroutines.
Function to selectively return a shield director if all of the following are true:
- The director points to a valid Fastly shield and is healthy
- It has not previously been visited in this request
Otherwise, the fallback director is returned.
This enables the specified shield site to be selected as a backend only once during a request's lifecycle, without the need to inspect headers or use a Fastly POP by its IATA identifier.
Example
sub vcl_miss { set req.backend = fastly.try_select_shield(ssl_shield_iad_va_us, req.backend);}