What is Docker and how it can make your life way easier?
Tags: docker, devops, tutorial, programming
Published: 2023-02-28 18:10:07

While working on a project for my degree at [42 Quebec](https://42quebec.com/en/home/), I discovered DevOps and thus a new passion. This little tutorial is the first of a series talking about Docker, Kubernetes, Ansible, Teraform and many other tools needed to become a great DevOps engineer. So let's start With Docker, but what is Docker and why is learning it such a big deal?
 
## Docker and Its Utility

Docker is a containerization platform that allows you to build, ship, and run applications in a consistent and portable way. It is used to package an application along with its dependencies into a container, which can then be deployed on any system that has Docker installed. Docker containers are lightweight, fast, and isolated, making them an ideal choice for deploying applications in production.

## How Docker Works

Docker works by using a layered file system and image-based containerization. Each Docker container is built from an image that includes all the dependencies needed to run the application. Images are built using a Dockerfile, which is a text file that contains the instructions for building the image. The Dockerfile specifies the base image, the commands to install the dependencies, and any additional configuration needed to run the application.

Once the image is built, it can be used to create Docker containers. Each container runs in its own isolated environment and has its own file system, network interfaces, and processes. Containers can communicate with each other through a shared network, making it easy to deploy and manage multiple applications on a single system.

## Benefits of Docker

There are several benefits to using Docker for application deployment:

### Portability

Docker containers are portable, meaning that they can be run on any system that has Docker installed. This makes it easy to move applications between development, staging, and production environments without worrying about dependencies or configuration issues.

### Consistency

Docker containers are consistent, meaning that they provide the same environment for running an application regardless of the host system. This eliminates the "works on my machine" problem that can arise when developing and deploying applications on different systems.

### Scalability

Docker containers are lightweight, meaning that they can be quickly spun up or down to meet changes in demand. This makes it easy to scale applications horizontally by adding or removing containers as needed.

### Isolation

Docker containers are isolated, meaning that they provide a secure environment for running applications without affecting the host system. This makes it easy to run multiple applications on a single system without worrying about conflicts or resource contention.

## Getting Started with Docker

To get started with Docker, you'll need to install Docker on your system. Docker provides installers for Windows, macOS, and Linux. Once Docker is installed, you can start building Docker images using a Dockerfile and creating Docker containers from those images.

Here's an example Dockerfile for a simple Node.js application:
```
FROM node:14-alpine

WORKDIR /app

COPY package*.json ./

RUN npm install

COPY . .

EXPOSE 3000

CMD ["npm", "start"]

```

This Dockerfile specifies that we want to use the `node:14-alpine` base image, set the working directory to `/app`, copy the `package.json` and `package-lock.json` files to the container, install the dependencies using `npm`, copy the application files to the container, expose port `3000`, and start the application using `npm start`.

To build the Docker image, run the following command:

``` docker build -t my-node-app . ```

This command tells Docker to build a Docker image with the tag `my-node-app` using the Dockerfile in the current directory (`.`).

To create a Docker container from the image, run the following command:
``` docker run -p 3000:3000 my-node-app ```

This command tells Docker to create a Docker container from the `my-node-app` image and map port `3000` on the host system to port `3000` in the container.

## Conclusion

Docker is a powerful tool for building, shipping, and running applications in a consistent and portable way. Its benefits include portability, consistency, scalability, and isolation, making it an ideal choice for deploying applications in production. With Docker, you can easily package your application along with its dependencies into a container and deploy it on any system that has Docker installed. Whether you're a developer, system administrator, or IT professional, Docker can help simplify your workflow and streamline your application deployment process. Give Docker a try and see how it can help you build and deploy applications more efficiently.

Learn more:
[Docker.com](https://www.docker.com/)
[tutorialspoint](https://www.tutorialspoint.com/docker/index.htm)

**_Tutorial: 1_**