This change is backward compatible, because the underlying types of
address.Offset (the previous type) and address.Count are the same
and the Gob encoder does not require types to exactly correspond.
- Nameserver holds a sorted list of (hostname, peer, container id, ip) tuples.
- Entries are gossiped using topology gossip / broadcast - only new/updated entries
are propogated as expected.
- Entries for a given peer are removed when the connection to the peer is lost.
- Entries are tombstoned when containers die. Tombstones are kept for 10mins,
as they do not need to survive partition, only gossip propagation delay.