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5. October 2025

• Add first_byte_timeout to shield backends

Every backend has a "first-byte timeout". This timeout applies to the HTTP response line and response headers. If the client (Compute instance) does not receive all the HTTP headers within the first-byte timeout, the Compute platform considers the request failed and returns a SendError (with e.g. SendErrorCause::HttpResponseTimeout) to the instance.

By default, all backends have a first-byte timeout of 15 seconds. This timeout is configurable for static and dynamic backends; however, it was previously not configurable for shield backends. If a shield POP took more than 15 seconds to complete writing its response headers, the Compute instance at the edge POP would receive a SendError.

This release adds Shield::with_first_byte_timeout, which creates a copy of the Shield with the first-byte timeout configured. Backends created from the resulting Shield (i.e. Shield::encrypted_backend, Shield::unencrypted_backend) will use the configured first-byte timeout.