I made a data_hash backend for hiera that uses the puppet certificate certname to connect to a remote http service and retrieve hieradata for a node. The http backend is up to you, in my implementation I also verified the certificate was signed by the Puppet CA.
This backend uses data_hash, so that it only looks up hiera once per catalog compilation. If it finds hieradata for a node, it updates the hiera cache.
The github repo is located here https://github.com/uphillian/http_data_hash