Every Kubernetes cluster is provisioned with a special service that provides a way for internal applications to talk to the API server. by the command kubectl get svc, we can see that service listed with the name ‘kubernates‘

A pod is the smallest execution unit in Kubernetes. A Kubernetes pod is a collection of one or more Linux® containers, and is the smallest unit of a Kubernetes application. A pod encapsulates one or more applications. Pods are ephemeral by nature, if a pod (or the node it executes on) fails, Kubernetes can automatically create a new replica of that pod to continue operations.  Pods include one or more containers (such as Docker containers) Pods represent the processes running on a cluster Any given

Below are the main components found on a (worker) node: kubelet – the main service on a node, regularly taking in new or modified pod specifications (primarily through the kube-apiserver) and ensuring that pods and their containers are healthy and running in the desired state. This component also reports to the master on the health of the host where it is running. kube-proxy – a proxy service that runs on each worker node to deal with individual host subnetting and expose services

The Kubernetes master runs the Scheduler, Controller Manager, API Server and etcd components and is responsible for managing the Kubernetes cluster. Etcd Etcd is a distributed, consistent key-value store used for configuration management, service discovery, and coordinating distributed work. API Server When you interact with your Kubernetes cluster using the kubectl command-line interface, we are actually communicating with the master API Server component. Scheduler The Scheduler watches for unscheduled pods and binds them to nodes via the /binding pod subresource API, according to

Kubernetes (also known as K8s) is open source software for deploying, scaling and managing containerized applications. As an orchestrator, Kubernetes handles the work of scheduling containers on a cluster and also manages the workloads to ensure they run as you intended. Features: Self-monitoring: Kubernetes checks constantly the health of nodes and containers Portable: Kubernetes offers portability, and faster, simpler deployment times.  High availability: Kubernetes addresses high availability at both the application and the infrastructure level.  Horizontal scaling: Kubernetes allows you scaling resources not only vertically

Docker supports several storage drivers, using a pluggable architecture. The storage driver controls how images and containers are stored and managed on your Docker host.  The Docker Engine provides the following storage drivers on Linux: overlay2 – overlay2 is the preferred storage driver for all currently supported Linux distributions, and requires no extra configuration.fuse-overlayfs – fuse-overlayfsis preferred only for running Rootless Docker on a host that does not provide support for rootless overlay2. On Ubuntu and Debian 10, the fuse-overlayfs

FROM – Sets the base imageMAINTAINER – Sets the author field of the generated imagesRUN – Execute commands in a new layer on top of the current image and commit the resultsCMD – Allowed only once (if many then last one takes effect)LABEL – Adds metadata to an imageEXPOSE – Informs container runtime portENV – Sets an environment variableADD – Copy new files, directoriesCOPY – Copy new files or directories into the filesystem of the containerENTRYPOINT – Allows you to

• A Docker image is a file used to execute code in a Docker container.• Docker images act as a set of instructions to build a Docker container, like a template.• Docker images also act as the starting point when using Docker.• An image is comparable to a minimal lightweight snapshot in virtual machine (VM) environments.• Docker image contains application code, libraries, tools, dependencies and other files needed to make an application run.• When a user runs an image, it

The Linux kernel device drivers are, essentially, a shared library of privileged, memory resident, low level hardware handling routines. It is Linux’s device drivers that handle the peculiarities of the devices they are managing. One of the basic features of is that it abstracts the handling of devices The following is a list of the types of docker storage driver which can be configured and their use case: • overlay2 – This is the preferred storage driver for all Linux distributions• aufs –

Docker Hub is a service provided by Docker for finding and sharing container images. Teams & Organizations can pull publicly available docker images for their usage. Top 5 docker repository Rank Repository 1 ubuntu 2 centos 3 nginx 4 redis 5 node

Docker wait command block until one or more containers stop, then print their exit codes Usage

The docker update command dynamically updates container configuration. For example : We can update a container’s kernel memory limit using the –kernel-memory option. You can update kernel memory while the container is running using below command:

The docker pause command suspends all processes in the specified containers. We can apply this command , if the container is in running stateThe docker unpause command un-suspends all processes in the specified containers. We can apply this command , if the container is in pause state docker pause <container name> docker unpause <container name>

Docker kill and stop are two command used to terminate the container execution.docker kill – Used to forcefully terminate execution of container, which does not attempt to shut down the process gracefully.docker stop – Used to terminate execution safely and gracefully. docker kill [OPTIONS] CONTAINER [CONTAINER…] docker stop [OPTIONS] CONTAINER [CONTAINER…]

Containerization is the grouping together of software components with all it’s necessary dependent elements, like libraries, frameworks, and other dependencies so the software execution isolate in their own environment.Such isolated user spaces are called “Containers”, docker engine is a is such a a containerization platform, that packages application and its dependencies together in the form of a docker container and run in an isolated environment.Advantages of Container technologies – Lightweight, independent, easy to mange and performance efficient.