Rolling updates are the cornerstone of managing large clusters. Kubernetes support rolling updates at the replication controller level and by using deployments. Rolling updates using replication controllers are incompatible with the horizontal pod autoscaler. The reason is that, during the rolling deployment, a new replication controller is created and the horizontal pod autoscaler remains bound to the old replication controller. Unfortunately, the intuitive kubectl rolling-update command triggers a replication controller rolling update.
Since rolling updates are such an important capability, I recommend that you always bind horizontal pod autoscalers to a deployment object instead of a replication controller or a replica set. When the horizontal pod autoscaler is bound to a deployment, it can set the replicas in the deployment spec...