Kubernetes Node Distribution and Availability: Implementation and Testing Notes

Implementation notes

A Kubernetes clusters control plane must be distributed over multiple physical machines, as well as different "failure zones". How these are defined is at the moment up to the CSP. Worker nodes can also be distributed over "failure zones", but this isn't a requirement. Distribution must be shown through labelling, so that users can access these information.

Node distribution metadata is provided through the usage of the labels topology.kubernetes.io/region and topology.kubernetes.io/zone.

Automated tests

Currently, automated testing is not readily possible because we cannot access information about the underlying host of a node (as opposed to its region and zone). Besides, access to control-plane nodes is problematic outside of a kubeadm-based setup.

Therefore, no automated tests are performed at this time.

Manual tests

Cloud-service providers must confirm that control plane nodes are indeed distributed over multiple physical machines.