What is Docker?

Docker is an open-source platform that enables developers to automate the deployment of applications inside lightweight, portable containers. These containers include everything the application needs to run—code, runtime, system tools, libraries, and settings—so that it can work reliably in any environment.

Before Docker, developers faced the age-old problem: “It works on my machine!” Docker solves this by providing a consistent runtime environment across development, testing, and production.

Why Learn Docker?

Docker is used by organizations of all sizes to simplify software delivery and improve scalability. As more companies shift to microservices, cloud computing, and DevOps practices, Docker has become a must-have skill. Learning Docker helps you:

Package applications quickly and consistently

Deploy apps across different environments with confidence

Reduce system conflicts and configuration issues

Improve collaboration between development and operations teams

Work more effectively with modern cloud platforms like AWS, Azure, and GCP

Who Is This Docker Tutorial For?

This Docker tutorial is designed for absolute beginners. Whether you're a developer, system administrator, QA engineer, or DevOps enthusiast, you’ll find step-by-step instructions to help you:

Understand the basics of Docker

Install Docker on your machine

Create and manage Docker containers

Build custom Docker images

Use Docker commands and best practices

No prior knowledge of containers is required, but basic familiarity with the command line and a programming language (like Python, Java, or Node.js) will be helpful.

What You Will Learn: Step-by-Step Breakdown

1. Introduction to Docker

We start with the fundamentals. You’ll learn:

What Docker is and why it’s useful

The difference between containers and virtual machines

Key Docker components: Docker Engine, Docker Hub, Dockerfile, Docker Compose

2. Installing Docker

Next, we guide you through installing Docker on:

Windows

macOS

Linux

You’ll set up Docker Desktop or Docker CLI and run your first container using the hello-world image.

3. Working with Docker Images and Containers

You’ll explore:

How to pull images from Docker Hub

How to run containers using docker run

Inspecting containers with docker ps, docker inspect, and docker logs

Stopping and removing containers

4. Building Custom Docker Images

You’ll learn how to:

Write a Dockerfile

Use docker build to create a custom image

Add dependencies and environment variables

Optimize Docker images for performance

5. Docker Volumes and Networking

Understand how to:

Use volumes to persist data outside containers

Create custom networks for container communication

Link multiple containers (e.g., a Node.js app with a MongoDB container)

6. Docker Compose (Bonus Section)

Docker Compose lets you define multi-container applications. You’ll learn how to:

Write a docker-compose.yml file

Start multiple services with a single command

Manage application stacks easily

Real-World Examples Included

Throughout the tutorial, we use real-world examples to reinforce each concept. You’ll deploy a simple web application using Docker, connect it to a database, and scale services with Docker Compose.

Example Projects:

Dockerizing a static HTML website

Creating a REST API with Node.js and Express inside a container

Running a MySQL or MongoDB database container

Building a full-stack web app with Docker Compose

Best Practices and Tips

As you progress, you’ll also learn:

Naming conventions for containers and images

How to clean up unused images and containers

Tagging and pushing images to Docker Hub

Security basics when using Docker in production

What’s Next After This Tutorial?

After completing this Docker tutorial, you’ll be well-equipped to:

Use Docker in personal or professional projects

Learn Kubernetes and container orchestration

Apply Docker in CI/CD pipelines

Deploy containers to cloud platforms

Conclusion

Docker is an essential tool in the modern developer's toolbox. By learning Docker step by step in this beginner-friendly tutorial, you’ll gain the skills and confidence to build, deploy, and manage applications efficiently and consistently across different environments.

Decoding Kubernetes and Docker

In this evolving era, Kubernetes and Docker have come up as powerful and vital tools in the DevOps industry. In this blog, we will dive into what is Kubernetes and Docker and their components. We will also learn about the difference, benefits and challenges faced with Kubernetes and Docker. Let’s begin!

What is Docker? Docker is a container management system and technology that was first launched in 2013. When growing, upgrading, or migrating to a new server, the system is highly handy. The Go programming language is used by Docker. The utility was originally only compatible with Linux hardware, but it is now also compatible with Windows and macOS systems. The project is no longer a…

What is docker

Docker is a computer program which is used to provide a running environment to run all kinds of application which are in docker hub, or created in docker. It creates an image of your application and stores all requirements of files into the container. Whenever we want to run docker application in any system, we have to run a single file without providing any other requirements.

Docker is easy to use in Ubuntu. It also supports Window and Mac operating system. For windows, it runs in Windows10/enterprise only. To use in Windows7/8/8.1 or Windows10 home should use docker toolbox.

There are two kind of docker software for programmers.

Docker CE :- Free community edition :- This is an open source software.

Docker EE :- Docker Enterprise Edition :- This is a paid software design for enterprise development and IT teams who build, ship, and run business-critical applications in production.

Requirements :-

Operating system (ubuntu)

Docker

Steps to install docker . Steps to download docker in ubuntu. 1.  Open terminal and follow these command to install docker.

Just type docker and check if docker is in your system or not. $ docker

2. To check the version of operating system. To install Docker CE, we need the 64-bit version of one of these Ubuntu versions: 1.  Cosmic 18.10  2. Bionic 18.04 (LTS) 3. Xenial 16.04 (LTS) $ lsb_release -a

3. Update the apt package index. $ sudo apt-get update

4. If requires, then install. $ sudo apt-get install

5. If docker is not in your system then install it. $ sudo apt-get install docker.io

6. Now check the staus of docker. $ sudo systemctl status docker

Steps to add user in docker 1. Why sudo :- We have to use 'sudo' command to run docker commands because docker container run user 'root'. We have to join the docker group, when your system join the docker group after that one can run docker command without sudo.

2. 'USER' is your system name, commands to add user as listed below. $user will pick system user 1. $ sudo groupadd docker 2. $ sudo gpasswd -a $USER 3. $ newgrp docker

3. Second way to add user in docker group.       1.  $ sudo groupadd docker        2.  $ sudo usermod -aG docker $USER

4. After adding a 'USER' into the docker group, we have to shut down or restart so that we can run docker commands without 'sudo'.

5. Command to uninstall docker. $ sudo apt-get remove docker docker-engine docker.io containerd runc

Docker commands 1.To check Docker version  $ docker --version

2. To check Docker and containers info $ docker info

3. Find out which users are in the docker group and who is allowed to start docker containers.  1.  $ getent group sudo

 2. $ getent group docker

4. 'pull' command fetch the 'name_of_images' image from the 'Docker registry' and saves it to our system. $ docker pull busybox (busybox is name of image)

5. You can use the 'docker images' command to see a list of all images on your system. $ docker images

6. To find the location of the images in the system we need to follow some commands:- $ docker info path of docker:- "Docker Root Dir: /var/lib/docker"

Commands to check the images:-

$ cd /var/lib/docker

$ ls

pardise@pardise-MS-7817:/var/lib/docker$ cd image

bash: cd: image: Permission denied

Permission denied for all users

$ sudo su

$ root@pardise-MS-7817:/var/lib/docker# ls

Now docker info command will provide all details about images and containers

$root@pardise-MS-7817:/var/lib/docker/image/overlay2# docker info

7. Now run a Docker container based on this image. When you call run, the Docker client finds the image (busybox in this case), loads up the container and then runs a command in that container. $ docker run busybox

8. Now Docker client ran the 'echo' command in our busybox container and then exited it. $docker run busybox echo "hello from busybox"

9. Command to shows you all containers that are currently running. $ docker ps

10. List of all containers that one can run. Do notice that the STATUS column shows that these containers exited a few minutes ago. $ docker ps -a CONTAINER ID – Unique ID given to all the containers. IMAGE – Base image from which the container has been started. COMMAND – Command which was used when the container was started CREATED – Time at which the container was created. STATUS – The current status of the container (Up or Exited). PORTS – Port numbers if any, forwarded to the docker host for communicating with the external world. NAMES – It is a container name, you can specify your own name.

11. To start Container $ docker start (container id)

12. To login in Container $ docker attach (container id)

13. To stop container $ docker stop (container id)

Difference between images and containers

Docker Image is a set of files which has no state, whereas Docker Container is the abstract of Docker Image. In other words, Docker Container is the run time instance of images.

Remove images and containers 1. Docker containers are not automatically removed, firstly stop them, then can use docker rm command. Just copy the container IDs. $ docker rm 419600f601f9 (container_id)

2. Command to deletes all containers that have a status of exited. -q flag, only returns the numeric IDs and -f filters output based on conditions provided. $ docker rm $(docker ps -a -q -f status=exited)

3. Command to delete all container. $ docker container prune

4. Command to delete all images. To remove all images which are not referenced by any existing container, not just dangling ones, use the -a flag: $ docker images prune -a

dangling image is an image that is not tagged and is not used by any container. To remove dangling images type:-

$ docker images prune

$ docker rmi image_id image_id......

5. Removing all Unused Objects. It will remove all stopped containers,all dangling images,and all unused network. To remove all images which are not referenced by any existing container, use the -a flag: $ docker system prune -a

Docker Swarm- A small introduction to docker swarm orchestration .