kubernetes/cmd/kubeadm/app/componentconfigs/kubelet_unix.go

// Mutate allows applying pre-defined modifications to the config before it's marshaled.
func (kc *kubeletConfig) Mutate() error { … }

// mutateResolverConfig mutates the ResolverConfig in the kubeletConfig dynamically.
func mutateResolverConfig(cfg *kubeletconfig.KubeletConfiguration, isServiceActiveFunc func(string) (bool, error)) error { … }

// isServiceActive checks whether the given service exists and is running
func isServiceActive(name string) (bool, error) { … }