DigitalOcean Droplet metadata service.

The service answers on the link-local address 169.254.169.254. No request needs an authentication header. /metadata/v1.json returns the whole metadata document in an array of one object.

The document reports the Droplet identifier and the region, for example nyc3. It reports no machine type, no zone, and no owner scope, so instance_type, zone, and scope_id are nil.

Detection needs a Droplet identifier and a region in the document.