Question: Which version of Kubernetes Supports fine with Spinnaker?

Answer:  In theory, Spinnaker should with any of the supported versions of Kubernetes. Clouddriver is responsible to connect with kubernetes and it uses kubectl binary to do so (V2 version). So, as the current version of kubectl of 1.16, Kubernetes versions up to 1.18 should work fine. Note that, if using halyard, one must use a relatively newer version of Halyard for for deployments to work as apps/v1beta2 has been depricated in Kubernetes 1.16.

Given a choice, we recommend k8s 1.15 with Spinnaker 1.17.6