kubectl is the Kubernetes command-line tool to deploy and manage applications on a Kubernetes cluster.
On Debian 9 (also know as Debian Stretch) it is included in the package kubernetes-client.
Describe a pod
If there is an issue with a pod not starting and logs don't say anything, use "describe" to get more info. For example:
kubectl describe pod P -n sessionstore
See Kubernetes#Managing_pods,_jobs_and_cronjobs for more.