This idea was imported from Canny. Originally created by: Matt Mercer. The current owner is: Unassigned.
Something like AWS EC2 identity documents (https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-identity-documents.html) providing a cryptographically signed summary of a Metal instance's attributes. Exposing this via the machine-facing metadata endpoint would provide a useful Secret Zero for authentication.