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Oluwanifesimi
Oluwanifesimi

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Steps to Containerize a Software Application

#linux #docker #containers #ubuntu

Introduction
Containerization has revolutionized modern software development by streamlining how applications are built, deployed, and maintained. In this guide, you'll learn how to containerize a simple Node.js Todo List Manager using Docker. By encapsulating the app and its dependencies into a container, you’ll gain consistency across environments, simplify deployment workflows, and enhance scalability.
Whether you're exploring Docker for the first time or brushing up on containerization fundamentals, this hands-on project will walk you through transitioning an app from a local setup to a fully containerized solution.

What You’ll Need
Before diving in, make sure your system is equipped with the following tools:

  • Docker Desktop (latest version): For building, running, and managing containers.
  • Git client: To clone the project repository and handle version control.
  • Code editor or IDE: Preferably Visual Studio Code for editing project files.
  • (Optional but helpful) Basic familiarity with terminal or command-line usage.

Step 1 : Get the app

  • Steps to Get the App and Run it in Visual Studio Code
  • Open Visual Studio Code

  • Launch VS Code on your computer.
    code

  • Open the Terminal

  • Click on Terminal at the top menu and select new terminal
    terminal

  • Clone the Application Repository

  • In the terminal, type the following command and press Enter:
    git clone https://github.com/docker/getting-started-app.git
    git clone

  • Navigate into the App Folder cd getting-started-app

  • Open the Folder in VS Code (Optional) code .
    cd

  • View the contents of the cloned repository. You should see the following files and sub-directories.
    content

Step 2 : Build image

To build the image, you'll need to use a Dockerfile. A Dockerfile is simply a text-based file with no file extension that contains a script of instructions. Docker uses this script to build a container image.

  • In the getting-started-app directory, the same location as the package.json file, create a file named Dockerfile with the following contents:

  • This Dockerfile starts off with a node:lts-alpine base image, a light-weight Linux image that comes with Node.js and the Yarn package manager pre-installed. It copies all of the source code into the image, installs the necessary dependencies, and starts the application.
    Image

  • Build the image using the following commands:
    docker build -t getting-started-app .

build

Step 3: Start an app container

Now that you have an image, you can run the application in a container using the docker run command.
Run your container using the docker run command and specify the name of the image you just created:
docker run -d -p 127.0.0.1:3000:3000 getting-started
run

Conclusion
Upon completing this project, you’ll have elevated a basic Node.js Todo List Manager into a fully containerized application. Along the way, you’ll build practical expertise in Docker — mastering commands, crafting images, and managing containers. These are essential capabilities for today’s DevOps practices and cloud-native development. More than just a technical exercise, this project empowers you to confidently deploy applications that are scalable, portable, and production-ready in diverse environments.

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