k8s in a nutshell

High level k8s arch

A k8s cluster has two kind of nodes

• control plane node: exposes the k8s API, so if you want to interact with the k8s cluster you need to go thru here.
• worker node: nodes that execute the workload. Needs to have a container runtime engine installed (containerd) for executing the containers.

Control Plane Node Components

• API server: expose k8s api
• Scheduler: Watches for new k8s pods and assign to nodes
• Controller Manager: watches the state of cluster, and makes changes
• etcd: a key-value that captures the state of the objects we create in the cluster

Common Node Components

Any node has these:

• Kubelet: agent that makes sure the containers are running in a k8s pod, usually this one runs in the workers.

• kube proxy: maintain network rules and allow communication

• Container runtime: software responsible for running containers