Could be possible to use the mysql.server table ? Could auto populate an information schema table when a slave connect and update a last seen date to produce warnings and errors in case of a outdated slave is picked by the command.

I would rather see a command more than a script as. One would like to create a corosync cluster plugin to be loaded inside MariaDB, synchronize all server information_schema.servers table with the corosync Totem Single Ring Ordering and Membership Protocol and can call such failover command on the Synchronization Engine plugin

Possible to add an option to set last executed GTID in the information_schema.servers replicate with corosync cluster API any node could decide who is the most up to date slave in a consistante state, proxy and connection pools could enter the group member to make proper switch over without losing any command. Connection and SQL not in the group member could be refused.

Check this out, golang so no dependencies like perl/python/ruby needs at install:

https://github.com/tanji/mariadb-tools

Blog post:
http://varokism.blogspot.co.uk/2015/06/slave-election-is-welcoming-gtid.html

I have removed the fixVersion for this task as it is one of 5.5, 10.1, 10.2, 10.3, which are EOLed.

Please add a new fixVersion if you plan to work on this task for a not EOLed versions.