Kubectl Exec: In addition to being able to attach to existing processes inside a container, the “exec” command allows you to spawn new processes inside existing containers

Kubectl attach: In addition to interactive execution of commands, you can now also attach to any running process. Like kubectl logs, you’ll get stderr and stdout data, but with attach, you’ll also be able to send stdin from your terminal to the program

What is Kubernetes?

Kubernetes is container orchestration tool
It enables to run multiple container with network enabled communication
It is open source tool which was developed by google and transferred to cncf
Kubernetes work on master and node configuration
Master has components : controller, apiserver, scheduler, etcd(kube store)
Atomic unit in kubernetes is pod
It works like helmsman

Why Kubernetes?

Kuberntes help in container orchestration which means it helps to place pods on different nodes in same network, so it resolves netorking issue which is there in using base containers like docker
It helps in load balancing of application deployed in kubernetes
It Helps in scaling containers
High availability and failover
It helps in reaching one click deployments
It help in Port mapping
Managing more and more docker images
It provides Storage
Tight coupling with Microservices
Good Product Support and documentation

How Kubernetes works?

controller – Control plane component that runs controller processes
Node controller: Responsible for noticing and responding when nodes go down.
Job controller: Watches for Job objects that represent one-off tasks, then creates Pods to run those tasks to completion.
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-apiserver – The API server is a component of the Kubernetes control plane that exposes the Kubernetes API.
The API server is the front end for the Kubernetes control plane.

kube – scheduler – Control plane component that watches for newly created Pods with no assigned node, and selects a node for them to run on.

etcd(kube store) – Consistent and highly-available key value store used as Kubernetes backing store for all cluster data.
It works on key value pair

What is POD?

Pods are the smallest deployable units of computing that you can create and manage in Kubernetes
Pods are a group of one or more containers, with shared storage and network resources
Pods are controlled by master(cluster) control manager
Pods are scheduled fro kube scheduler
Pods can have multiple container
multiple pods should not be deployed in single node
pod can communicate with each other in network