>   (* The server name or UUID of the conversion appliance where

>    * virt-v2v is currently running.  In future we may be able

>    * to make this optional and derive it from the OpenStack

>    * metadata service instead.

>    *)

>   server_id : string;

Indeed, it can be derived from OpenStack metadata service. The following URL called from within the conversion appliance will return the metadata: http://169.254.169.254/openstack/latest/meta_data.json. As you can see, the IP address is 169.254.169.254, which will is the metadata service. The JSON body contains a uuid entry that is the current appliance UUID, hence the server_id used by virt-v2v.

I don't know how to code that in OCaml, so I defer implementation to anyone with such skills. And by reading the patch, I may learn how to write small pieces of OCaml and contribute further changes :)