I realized that allowing hosts to request certificates for arbitrary
aliases sort of defeats the purpose of the authentication process. If a
host successfully authenticates, there would be nothing stopping it from
requesting a certificate for another host. I will have to come up with
a different way of specifying aliases. Probably something like a JSON
map containing pre-assigned aliases for hosts that will need them.
Since hosts have multiple keys that they will want to have signed, they
will need to make multiple requests, either sequentially or in parallel.
Since each request must be authenticated individually, this would result
in a libvirt connection and lookup for each one. To avoid this
overhead, the server will now cache machine IDs in memory for 60
seconds.