Create a request header transform rule to add an HTTP header when the Workers subrequest comes from a different zone.
The following request header transform rule adds an HTTP header to Workers subrequests coming from a different zone:
Text in Expression Editor (replace myappexample.com with your domain):
(cf.worker.upstream_zone != "" and cf.worker.upstream_zone != "myappexample.com")Selected operation under Modify request header: Set static
Header name: X-External-Workers-Subrequest
Value: 1
The cf.worker.upstream_zone field used in the rule expression is set to empty if the current request is not a Workers subrequest.
