Docker Introduction for beginners

Introduction

Docker is a developer tool released in 2013 by docker team.
It is a centralized platform to execute your application.
It is a facility to run applications in an isolated environment.
Using docker we can build, ship and run any app.
It is very similar to virtual machine concept.
Docker fallows client-server architecture.

Architecture

Installation
To install docker in windows machines:https://docs.docker.com/docker-for-windows/install/
(or)

Install the Docker tool Box: https://docs.docker.com/toolbox/toolbox_install_windows/

Components

Docker follows client-server architecture.
Docker has three main components those are

Docker CLI (command line interface)

Docker host(Docker daemon )

Registry(Repository)

Pull and push images

To pull the image from the docker hub uses the following command: docker pull (image name: tag name).
To push the image into docker hub(registry ) first tag the image to the repository and then push into the docker hub.
Docker tag image-id yourdhubname/repo name: tag name
docker push yourdhubname/repo name

Docker-file

It is the main part of your docker image, based on this file application will package to image.
Docker files have no extensions.
Use the predefined commands to package the application provided by docker.
FROM ,COPY ,CMD,MAIN,MAIN-CLASS etc.
From: Define the base image used to start the build process. for java applications build to use OpenJDK:8
Add: Copy the source file into the container. Here I Added the targeted the jar file and second argument as a jar file name as which you want to name it.
Expose: Expose the port number to a web application. (binding the port into an application)
Entry point: Set a default application to be used every time a container is created with the image.

Managing Containers

The container is an instance of images. These are continuously running on docker daemon.
We can manage the container using the commands to stop and start and remove the containers.
Every container has one unique id so we can easily identify which container to stop and start.
To start the container using the following command: docker start imageid.
To stop the container using the following command: docker stop imageid.
To remove the container using the following command: docker rm imageid.

Useful Commands

Docker ip:docker-machine IP
Docker running process: docker ps and docker ps -a
Docker images: docker images
Pull image: docker pull image name:tag name
Run image:docker run imageName
Remove image:docker rmi imageId
Build the image: docker build -t tag-name.
Tag image: docker build tag imageid hub name/repo name: tag name
Push image: docker push hubname/repo

Conclusion

Open source and easily configurable.
Lightweight and Very fast to deploy the applications into containers.
Sharing applications are easy to process.
Run the multiple containers at a time.
Deploy applications any platform and run the application anywhere.
Less CPU utilization.
Less memory occupancy.

Docker Introduction for beginners

janardhan Randhi

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