code: func (config *inClusterClientConfig) Possible() bool {
  	fi, err := os.Stat("/var/run/secrets/kubernetes.io/serviceaccount/token")
  	return os.Getenv("KUBERNETES_SERVICE_HOST") != "" &&
  		os.Getenv("KUBERNETES_SERVICE_PORT") != "" &&
  		err == nil && !fi.IsDir()
  }
docs: // Possible returns true if loading an inside-kubernetes-cluster is possible.