Kubernetes Master and Node Components

Kubernetes Master


  • Kubernetes master runs on Linux nodes

Master Components


  • This component is Central to Kubernetes. All communications between all components goes through the kube-apiserver
  • This component is frontend of the Kubernetes control plane.
  • This component exposes a REST API.
  • We would interact with this component using kubectl by using the YAML files, which are also referred as manifests


  • etcd stores the entire configuration and the state of the cluster.
  • etcd is consistent and highly available distributed key-value store.


  • It watches for new work tasks and assigns them to healthy nodes in the cluster


  • It is responsible for maintaining desired states mentioned in the manifest.
  • It looks like single component, but with in it has
    • Node Controller: for noticing & responding when node goes down
    • Replication Controller: for maintaining the correct number of pods for every replication controller object.
    • Endpoints Controller: Populates the Endpoints object


  • If you run the Kubernetes on a supported cloud platform such as AWS, Azure or Google, your control plane runs the Cloud-Controller-Manager.
  • It is responsible for underlying cloud specific controllers.

Node Components



  • This is an agent which runs on each node in the cluster.
  • It watches for the instructions from API Server for new work assignments.
  • If it can’t run the task assigned, it reports back to master and lets control plane decide on the actions.
  • It is responsible for the node registration process

Container Runtime

  • This is software which is responsible for running containers.
  • Some of them are Docker, containerd, cri-o, rktlet


  • Maintains the network rules on nodes
  • This is responsible for networking on nodes.

Cluster DNS

  • Every Kubernetes Cluster has an internal DNS service
  • This has static IP address that is hardcoded into every Pod on the cluster i.e. all Pods now how to find the DNS Server
  • Services, Stateful Sets and Pods are registered with Cluster DNS.
  • Cluster DNS is based on CoreDNS

Interesting ADD ONS

Web UI (Dashboard)


  • Web based Kubernetes user interface
  • Capabilities:
    • Deployment
    • View cluster resources
    • Troubleshooting

Container Resource Monitoring

  • We will discuss about it in next series of articles

Cluster Level Logging

  • We will discuss about it in next series of articles

How to Package Apps To Run on Kubernetes


  • Package your application as container image.
    • We would create a Image for the application
    • Push the image to Docker Registry
  • Pod will Wrap container
  • Pod is deployed into Kubernetes cluster via Declarative Manifest file.

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devops & cloud enthusiastic learner