The master switchover script worked nicely for T197073, but it needs some extra features:

• Have it fully documented on wikitech so it can be used by any op
• have a dry-run feature where it goes over each step, but doesn't really change anything
• Provide timestamps for each step executed
  • Total read_only time on a MySQL level
• More pre-flight checks such as
  • is pt-heartbeat running on the current master?
• Make heartbeat migration more robust until it is migrated to a systemd service or moved remotely (so it is automatic and etcd-dependent)
• It alters or checks some master-related variables automatically (pt-config-diff h=localhost /etc/my.cnf ?):
  • Alter expire_log_days variable
  • Alter gtid mode automatically
  • Alter semi-sync automatically