for the kubelet in the dropin, a structured configuration file for the kubelet is used, and is expected to be present in `/var/lib/kubelet/config.yaml`. For runtime-detected, instance-specific configuration values, a environment file with dynamically-generated flags at `kubeadm init` or `kubeadm join` run time is used. Finally, if you want to override something specific for the kubelet that can't be done via the kubeadm Configuration file (which is preferred), you might add flags to the `KUBELET_EXTRA_ARGS`...