Day 08_OS Level Virtualization, Creating Custom Image.txt

											DOCKER - Basics to Brilliance
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DAY 08
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OS Level Virtualization
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=> It is the process of using the resources in an effective way.

=> Hardware ---- Host OS ---- Hypervisor ---- VMs ----- Apps

=> OS Level Virtualization means, for example, if I have an OS, inside the OS I have some folders, files, softwares, packages, code, etc., if I want to take the backup of complete OS, then it is known as OS Level Virtualization.

# To delete a stopped container
$ docker rm <ContainerName>

# To delete all the containers in the stopped state
$ docker container prune

# To delete all the stopped cotnainers, unused images, and unused networks
$ docker system prune -a

# To delete a running container, firstly you have to stop the container;
$ docker stop <ContainerName>
$ docker rm <ContainerName>

OS Level Virtualization
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$ docker pull ubuntu									---> To pull the ubuntu image
$ docker images										---> To see the list of images
$ docker run -it --name <ContainerName> <ImageName>		---> To create and run the container at the same time
Now you will be inside the 'ubuntu' container i.e container001 (in my case)
$ apt update -y											---> To update the packages
$ apt install git -y										---> To install git
$ git --version											---> To verify the git installation
$ apt install maven -y									---> To install maven
$ mvn --version										---> To verify the maven installation

Currently we have installed the git and maven s/w inside the container (container001).

Inside the container we have the ubuntu image. Inside the ubuntu image, OS is there. Inside the ubuntu OS, I have installed git and maven s/w and also I have created 2 python and 2 java files.

Lets copy the content from container to image;
Inside the container we have ---> git s/w, maven s/w, 2 java files, and 2 python files.
Now lets create the custom image using the container001.
The name of the image i'm going to create is "KASTRO"
The new image i.e "KASTRO" image container the content whatever thai is available in container001

To copy the content from the container to image, we will use 'commit' command
$ docker commit <ContainerName> <GiveCustomImageName>

# To create a container from the custom image
$ docker run -it --name <ContainerName> <ImageName>
You will be inside the newly created container;
Execute ls command to see the files
Execute git --version and mvn --version to see the s/w

If you are able to see everything then it is known as OS Level Virtualization (Complete Backup of OS)

The process whatever we have done so far is not followed in the real-time scenarios. Because it is completely a manual process.

In order to do the automation process, we have to create a dockerfile. Inside the dockerfile we are going to write/configure everything that we need to install. 

The purpose of dockerfile is to do the image automation. This is done in real-time scenarios. 

The automation in real-time is done by using dockerfile


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															By 
													KASTRO KIRAN V
								Connect with me on LinkedIn: https://www.linkedin.com/in/kastro-kiran/
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