Kubernets

Kubernetes is free and open source technology for automating the deployment, scaling and management of containerized applications. It is being used by major cloud providers like Google, Microsoft, IBM and Alibaba to run their container-based workloads Kubernetes also allocates storage and persistent volumes to running containers, provides automatic scaling, and works continuously to maintain the desired state of applications, providing resiliency.

Kubernetes Architecture

The architecture of Kubernetes actually follows the client-server architecture. It consists of the following two main components: 1.

Master Node or Kubernetes Control Plane

2. Worker or Slave node

1. Master Node or Kubernetes Control Plane :  The master node in a Kubernetes architecture is used to manage the states of a cluster. It is actually an entry point for all types of administrative tasks. In the Kubernetes cluster, more than one master node is present for checking the fault tolerance.  Different components which exist in the Master node or Kubernetes Control plane:    

API Server Scheduler Controller Manager ETCD

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API Server :  Kubernetes uses the API server to perform all operations on the cluster.  It is a central management entity that receives all REST requests for modifications, serving as a frontend to the cluster.  Implements an interface, which enables different tools and libraries to communicate effectively.

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Scheduler :  The scheduler assigns the tasks to the slave nodes.  It is responsible for distributing the workload and stores resource usage information on every node.  Tracks how the working load is used on clusters and places the workload on available resources.

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Controller Manager :  A daemon (server) that runs in a continuous loop and is responsible for gathering information and sending it to the API Server.  Works to get the shared set of clusters and change them to the desired state of the server .  The key controllers are the replication controllers, endpoint controller, namespace controllers, and service account controllers.  The controller manager runs controllers to administer nodes and endpoints.

 ETCD :  It is an open-source, simple, distributed key-value storage which is used to store the cluster data. It is a part of a master node which is written in a GO programming language.  It communicates with all other components to receive the commands to perform an action.

2. Worker or Slave node :  The Worker node in a Kubernetes is also known as minions. A worker node is a physical machine that executes the applications using pods. It contains all the essential services which allow a user to assign the resources to the scheduled containers.  Following are the different components which are presents in the Worker or slave node:  Kubelet  Kube-proxy  Pods

 Kubelet : Every kubelet in each worker node communicates with the master node. It also starts, stops, and maintains the containers which are organized into pods directly by the master node.

 Kube-proxy : It is a proxy service of Kubernetes, which is executed simply on each worker node in the cluster. The main aim of this component is request forwarding

 Pods : A pod is a combination of one or more containers which logically execute together on nodes. One worker node can easily execute multiple pods.

Features of Kubernetes:

Conclusion:  Kubernetes is a free and open source project.  It is being used by many cloud providers to run their Container-based workloads.  As it is a free tool, you don’t have to pay for the licensing fees of the software.  So, you can save a lot of money by using the free version of the tool.