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5. Client request

STRING, read-only.

Available inall subroutines.

Request ID that is generated by each cache server.

If you have shielding or clustering enabled, the value will change as the request moves from one Fastly server to another.

In most cases, set a request header using a UUID instead. For example:

if (!req.http.Request-ID) {
  set req.http.Request-ID = uuid.version4();
}