Kubelet leads all activities on the nodes. They are the sole point of contact from the master node. They load or unload containers on the node as instructed by the scheduler on the master. They also send back reports at regular intervals on the status of the node, and the containers on them.
The Kubelet in the Kubernetes worker node registers the node with the Kubernetes cluster. When it receives instructions to load a container or a pod on the node, it requests the container run time engine, which may be Docker, to pull the required image and run an instance.
The Kubelet continues to monitor the state of the pod and containers in it and report to the Kube API Server in the master node on a timely basis.
If you use Kubeadm tool to deploy your cluster, it does not automatically deploy the Kubelet. You must always manually install the Kubelet on the worker nodes.
View kubelet options
ps -aux | grep kubelet # root 888 1.8 4.6 1857228 95196 ? Ssl 03:59 5:38 /usr/bin/kubelet --bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf --config=/var/lib/kubelet/config.yaml --network-plugin=cni --pod-infra-container-image=k8s.gcr.io/pause:3.2 # vagrant 5162 0.0 0.0 14864 1056 pts/0 S+ 08:56 0:00 grep --color=auto kubelet