[Bugs] [Bug 1241274] New: Peer not recognized after IP address change

[bugzilla at redhat.com]

https://bugzilla.redhat.com/show_bug.cgi?id=1241274

            Bug ID: 1241274
           Summary: Peer not recognized after IP address change
           Product: GlusterFS
           Version: mainline
         Component: glusterd
          Assignee: bugs at gluster.org
          Reporter: jdarcy at redhat.com
                CC: bugs at gluster.org, gluster-bugs at redhat.com



In a user environment, a server might be migrated/restarted with a different IP
address than it had before.  DNS has been updated to point the old name at the
new address, and thus clients can still reconnect to it OK, but other servers
fail to recognize it as a cluster member because of the address change.  In
this particular case, the problem is related to containerization of the
servers, but it can also occur with bare-metal failover solutions.  The key
factor is really that the user is unable/unwilling to configure their routing
so that a floating service address can be reassigned to a new physical machine
in case of failover or migration.

Extra detail: the problem occurs because the *recipient* of a "peer probe"
message initially stores the sender's string-valued IP address instead of its
name.  If we then probe in the other direction using that peer's name, we
update our peer record with that as well, but that's a total hack and doesn't
seem totally foolproof either.  A better solution is to store and subsequently
compare against reverse-resolved host names for probes we receive, whenever
such names are available.  Such an approach would be effectively immune to such
address changes (though it doesn't solve the general problem of DNS errors or
misconfiguration).

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