[jonenst]

To me the core of k8s is pod scheduling on nodes, networking ingress (e.g. nodeport service), networking between pods (everything addressable directly), and colocated containers inside pods.

Declarative reconciliation is (very) nice but not irreplaceable (and actually not mandatory, e.g. kubectl run xyz)

[jakewins]

After you’ve run kubectl run, and it’s created the pod resource for you, what are you imagining will happen without the reconciliation system?

You can invent a new resource type that spawns raw processes if you like, and then use k8s without pods or nodes, but if you take away the reconciliation system then k8s is just an idle etcd instance

[jonenst]

Since they had the reconciliation system because they decided the main use case was declarative, it makes sense that they used it to implement kubectl run. But they could have done it differently.

Imagine if pods couldn't reach other and you had to specify all networks and networking rules.

Or imagine that once you created a container you had to manually schedule it on a node. And when the node or pod crashes you have to manually schedule it somewhere else.