[ssk2]

Scaling happens at two levels: both for the deployments and for the size of the cluster itself. Clusterman operates on the cluster itself.

If you scale just the number of pods, if there isn't enough available capacity in the cluster, they are unable to deploy until that capacity brought online. By emitting a signal to increase the number of nodes in the cluster just before we think that capacity is about to be needed, we can ensure that the new pods are launched near instantly when the deployment is actually scaled up. This is mostly useful when you're scaling by large increments (i.e. hundreds of pods) that far exceed the spare capacity available in your cluster.

[gravypod]

What benift does that distinction give you? If the cluster scales to be able to run all of your pending pods, and scales down when you have extra room, and you scale your pods correctly (preemptively & with custom metrics), what do you gain?

[ssk2]

Mostly time. For workloads that are pseudo interactive (e.g. continuous integration), you're saving developers a 10-20 minutes here or there. That can add up to be quite a bit for a medium to large organisation.