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Leader Election, Addons, and Node Autoscaling

The cluster runs three control planes, but controller-manager and scheduler keep only one instance active at a time — if all three acted, they'd step on each other. This article looks at the mechanism that prevents that: leader election via a Lease, and proves real failover by taking the leader down and watching another controller win the lock. Then it closes Part XIII with addons and node autoscaling — adding and removing machines by load.