kube-apiserver
kube-scheduler
kube-controller-manager
etcd
Kubelet
kube-proxy
It acts as frontend for Kubernetes cluster. users, management devices and command line interfaces interactive API server to talk with Kubernetes cluster.
Etcd is a Consistent and highly-available key value store used as Kubernetes' backing store for all cluster data.
Kubernetes stores all the date related master, nodes, pods, etc in the etcd. It is distributed across the cluster.
Kube scheduler watches for newly created Pods with no assigned node, and selects a node for them to run on.
It is responsible to identify in case of node or pod failures and replace with new container or pod
Logically, each controller is a separate process, but to reduce complexity, they are all compiled into a single binary and run in a single process.
These controllers include:
Node controller: Responsible for noticing and responding when nodes go down.
Replication controller: Responsible for maintaining the correct number of pods for every replication controller object in the system.
Endpoints controller: Populates the Endpoints object (that is, joins Services & Pods).
Service Account & Token controllers: Create default accounts and API access tokens for new namespaces.
It comes into the picture incase cluster is running in the cloud environment.
An agent that runs on each node in the cluster. It makes sure that containers are running in a Pod.
kube-proxy is a network proxy that runs on each node in your cluster, implementing part of the Kubernetes Service concept.
kube-proxy maintains network rules on nodes. These network rules allow network communication to your Pods from network sessions inside or outside of your cluster
it is a underlying software which is used to run our pods