Less configuration

[vincentbernat]

Hey!

To lessen the amount of configuration needed, the only mandatory parameter could be the EIP to use. exoip would add the current VM to the specified EIP and retrieve the peers from the API (those are VM that share the EIP). The cluster ID would be the EIP. The list of peers need to be refreshed at regular interval (or maybe only when the current master goes down for non-master or when the master receives messages from unknown peers). The metadata server could be used to retrieve the current VM.

[pyr]

The cluster ID is already the EIP. Priority is the same for all hosts by default so doesn't need to be provided. I wondered about adding support for fetching the current machine's NIC.

[pyr]

I disagree with fetching the list of peers from the API though, for now, it will be too brittle.