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Sandhya K
Sandhya K

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Architecture of Kubernetes and few lines for each component and What is POD, write a 10 lines explaination on POD by Sandhya

  • Kubectl - manifest file (JSON/yaml) input on the required cluster requirement

*Master Node *

  • apiserver - Front end for master node,
    - Takes manifest file for input, Updates etcds, informs scheduler on new pod requirements and so on

  • Cluster store - Persistent storage for cluster state info (etcd)

  • kube-controller manager - Controller of Controllers , Manages the various nodes in cluster.

  • kube-scheduler - Watches apiserver for new pods and schedule them as per the requirement or availability

  • kube-proxy - Takes care of Cluster networking
    - Updated the ip tables about the ports numbers and the port mapping of the pods after assigning them.

worker nodes

  • kubelet - main kubernetes agent in worker node
    - instantiates pods in the node and report back to master
    - Register the node with the cluster by informing the apiserver

  • Container engine - Manages containers in the node

*Pod *

  • Process in node which comprises of 1 or many containers.

  • Pod state will directly depend on state of containers running in it.

  • Pods can be instantiated as its a process.

  • Redeployment not possible. Once a pod is deleted, its gone but a similar one can be cretaed.

  • instantiated by kubelet

  • Pod state -> pending -> running -> succeeds/fails based on container state

  • Interpod communiation - Pod network

  • Intra pod container - local host

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