Performing rolling updates with autoscaling

Rolling updates are the cornerstone of managing large clusters. Kubernetes supports rolling updates at the replication controller level and by using deployments. Rolling updates using replication controllers are incompatible with the HPA. The reason is that during a rolling deployment, a new replication controller is created and the HPA 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 HPAs to a deployment object instead of a replication controller or a replica set. When the HPA is bound to a deployment, it can set the replicas in the deployment spec and let the deployment take care of the necessary underlying rolling update and replication.

Here is a deployment configuration file we've used for deploying the hue-reminders service...