STRING, can be read, set and unset.

Available in all subroutines.

Request headers sent by the client.

Request headers are also frequently used as variables to store strings for later use. Fastly VCL also offers local variables as an alternative for storing temporary values.

Due to Fastly's clustering, request headers set in a subroutine that runs on a shield will not be transferred back to the edge.

User contributed notes

We welcome comments that add use cases, ideas, tips, and caveats. All comments will be moderated before publication. To post support questions, visit our support center and we'll find you the help you need.