Completek8s Classroomnotes 19/Jul/2023

Container Orchestration

  • Orchestration in Compute: This is about
    • automated configuration
    • management
    • co-ordination of systems, applications and services
  • Container Orchestration is
    • automation of operational effort required to run containerized workloads and services
    • managing
      • container lifecycle
        • provisioning
        • deployment
        • scaling
      • networking
      • storage


Rest API

  • This is a standard way of exposing functionality over http(s)
  • Refer Here for what rest api
  • Verbs:
    • GET
    • PUT
    • POST
    • DELETE

Kubernetes (k8s)

  • Basic kubernetes cluster
  • Kubernetes cluster
  • Kubernetes has components categorized based on where they are executing
    • Control Plane
      • kube-api Server
      • kube-scheduler
      • kube-controller-manager
      • etcd store
    • Worker Node
      • kubelet
      • container engine
      • kube-proxy
  • Any system which wants to interact to kubernetes should have kubectl

kube-api server component

  • This is most important component of the k8s control plane
  • kube-api server exposes REST API which enables clients to send HTTP requests to kube-api server
  • kube-api server responds over http requests and writes the resource information to etcd store
  • kube-api server exposes the k8s objects
  • kube-api server is responsible for all the communication
  • The api server is over https and requires authentication

etcd store

  • This is memory of k8s cluster Refer Here
  • etcd cluster can scale across multiple nodes unlike traditional databases


  • This polls the kube-api server for any new objects in etcd store which are not scheduler
  • For any workloads unscheduled k8s scheduler will find a suitable worker node and then creates the workload


  • This ensures the desired state is met.
  • This is combination of multiple controller
    • NodeController
    • Replication Controller
    • Namespace Controller
    • EndpointController
    • ServiceAccountController


  • This is an agent on the worker node
  • This reacts to requests/orders from control plane components and speaks with container runtime and gets the work done
  • If it fails responds back to control plane with status

Container Runtime

  • this is container engine
  • this could be docker or any other CRI compatible runtime


  • this is responsible for networking
  • this implementations will be based on CNI

Getting familiar with tmux

  • Install tmux on linux

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