Intro to docker

Hello all, In this article we are going to see "what is a Docker ?".
In this we just see the  basic of docker "definition and installation" and in next article of this series we will see the technical part of the docker " Top commands to get familiar with docker ".
Let's began,


#Definition 

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1. Why need of docker occur  

           
 * In every SDLC when the project moves from production to developer it will cause many dependencies issues example: A project is working well in a developer's system but when the project is deployed to the server then many things will not work well

* solution for above problem: Most of the people uses Virtual machine to solve this dependencies issues and a VM can easily solve this dependencies issues. A developer just need to setup the same VM in server and need to deploy project there but there is many drawback of VM and here docker comes.

*  So a Docker is a kind of VM, which solves the dependencies issues and solves drawback of VM.

 2. Benefits of Doker over a Virtual Machine   

* A VM needs its own personal OS which require lot of resources, Where a docker not needs a personal OS it will run over a host OS, Docker only require a docker engine to executes its containers.

3. Technical definition of Docker 

* Docker is a tool designed to make it easier to create, deploy, and run applications by using containers. Containers allow a developer to package up an application with all of the parts it needs, such as libraries and other dependencies, and ship it all out as one package. By doing so, thanks to the container, the developer can rest assured that the application will run on any other Linux machine regardless of any customized settings that machine might have that could differ from the machine used for writing and testing the code.

* In a way, Docker is a bit like a virtual machine. But unlike a virtual machine, rather than creating a whole virtual operating system, Docker allows applications to use the same Linux kernel as the system that they're running on and only requires applications be shipped with things not already running on the host computer. This gives a significant performance boost and reduces the size of the application.

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#Installation  

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 * following are the steps for docker installation in ubuntu system

 1. open terminal 

 2. type : " sudo apt-get update " : this will download package list from ubuntu repository .

 3.type : " sudo apt-get remove docker docker-engine docker.io " : this will remove the older version of docker.

 4. type : " sudo apt install docker.io " : this will install the docker.io package .

 5 type : " docker -version " : to check docker version , if this will not show any thing then repeat whole process from starting.

 6. type : " sudo systemctl start docker " : this will start the docker.

 7. type : " sudo systemctl enable docker " : this will save the setting of docker of future .

 # docker installed  successfully  

 # In next article we will see the basic commands to use docker.

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