Kubernetes Components

A Kubernetes cluster consists of the components that represent the control plane and a set of machines called nodes.

Control Plane Components

etcd:

etcd is the consistent and highly available key value database used by Kubernetes as backing store for all cluster data.

API Server:

API Server exposes the Kubernetes API. API Server is the front-end component in the Kubernetes cluster. All cluster operational requests are receiving by API server to control the cluster operations.

Kube-Controller Manager

Manages controller processes in the cluster, below are the controller processes responsible for various operations.

• 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

Kube-Scheduler

Scheduler is responsible to monitor newly created pod and assigns the node where the pod can run. Kube-scheduler consider various factors to select the node where the pod can run like,

• Individual and collective resource requirements
• Hardware/software/policy constraints
• Affinity and anti-affinity specifications
• Data locality
• Inter-workload interference, and deadlines.