If the -hostname flag is passed, the node will startup and be accessible from
remote nodes using the specified hostname. At startup, we attempt to update
the hostname if it's different. For data-only nodes, this is pretty straight-forward.
For nodes part of the raft cluster, it is much more complicated as the the cluster
must be up and stable (with a leader) for a the update to take place. The main
complication in this case is that the node starting up will have a different
hostname and will fail to take part of the raft cluster because each other node
does not have this new name in the it's raft peers list. Since this is very problematic
and very easy to break a cluster, this PR just aborts startup and alerts the operator that
some manual actions must be taken to update the raft peer on all raft members before
the hostname can be fully updated.
Fixes#3421
Hostnames were always being resolved to an IP address and the IP
address was used as the host address and raft peer address. There
was no way to use an actual hostname instead of an IP address.
Jason Wilder