>Everything is, in principle, controllers mediating between the data model and the real world. Very elegant and orthogonal.
If you distill k8s down to this model alone, k8s becomes nothing but a pattern that has existed for decades. Maintaining "desired state" and "operational state" as separate things is not new.
You missed my point; I didn't say it's new, I said it was simpler than it might seem, and that thinking of it as a state machine makes it easier to understand what the core of Kubernetes really is.
And of course "nothing but a pattern" is nonsense. Pre-container systems like Puppet and Chef -- which are also, vaguely, based on converging real state towards desired state -- are firmly rooted in the traditional Unix model of mutable boxes. You can't implement a consistent reconciliation loop if your state can't be cleanly encapsulated (as with containers).
If you distill k8s down to this model alone, k8s becomes nothing but a pattern that has existed for decades. Maintaining "desired state" and "operational state" as separate things is not new.