Kubernetes – Kubelet

Kubelet is an agent that runs on each node in a Kubernetes cluster and is responsible for managing the state of containers on that node. It communicates with the Kubernetes control plane to receive instructions on which containers to run and how to run them. In this way, it ensures that the desired state of the cluster is maintained.

Here are some key features and responsibilities of Kubelet:

• Pod management: Kubelet manages pods on the node by starting, stopping, and restarting containers as necessary. It ensures that the containers in a pod are running and healthy, and that the pod is running on the node it’s supposed to be on.
• Container runtime interface: Kubelet communicates with the container runtime on the node (such as Docker or containerd) to start and stop containers. It also monitors the health of containers and restarts them if they fail.
• Volume management: Kubelet manages the volumes that are mounted inside containers. It ensures that the volumes are properly mounted and that their contents are available to the containers.
• Node status: Kubelet reports the status of the node to the control plane. This includes information about the resources available on the node (such as CPU and memory), as well as the status of the containers running on the node.
• Health checks: Kubelet performs periodic health checks on the containers it manages to ensure that they are running and healthy. If a container fails a health check, Kubelet will try to restart it.
• Security: Kubelet enforces security policies on the containers it manages. For example, it ensures that containers are running with the correct permissions and that they are isolated from each other.

Overall, Kubelet plays a critical role in the operation of a Kubernetes cluster by managing containers and pods on each node. Its responsibilities range from container runtime management to health checking and reporting node status.