Project: Containerize a Simple Application

Practical project to containerize a simple web application using Docker.

By Kevin McAleer,    3 Minutes

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Project Overview

This practical project is designed to give you hands-on experience with Docker. You will containerize a simple web application, learning the entire process from creating a Dockerfile to running the application in a container. This exercise will solidify your understanding of Docker and its application in real-world scenarios.

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Step-by-Step Guide

Application Overview

• Web Application: For this project, consider a basic web application, such as a simple Python Flask or Node.js app.
• The application should have a basic functionality, like displaying a static page or returning a response to a web request.

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Creating a Dockerfile

1. Dockerfile Basics:
   • Start with specifying the base image, like python:3.8 or node:14.
   • Set a working directory in the container, e.g., WORKDIR /app.
2. Adding Application Files:
   • Use the COPY command to copy your application files into the container.
3. Installing Dependencies:
   • For Python, copy the requirements.txt file and run pip install.
   • For Node.js, copy the package.json file and run npm install.
4. Setting the Run Command:
   • Use the CMD command to set the command that runs your application, such as python app.py or npm start.

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Building the Image

• Run docker build -t myapp:latest . to build the Docker image from your Dockerfile.
• The -t flag tags your image, and . indicates the current directory as the build context.

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Running the Container

• Once the image is built, run it with docker run -p 5000:5000 myapp:latest.
• The -p flag maps a port on your host to a port in the container.

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Testing and Deployment

Testing Your Container

• Local Testing: Access your application by navigating to http://localhost:5000 in your web browser.
• Ensure all functionalities work as expected in the containerized environment.

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Tips for Deployment

• Container Registry: Consider pushing your image to a container registry like Docker Hub for easy deployment.
• Environment Variables: Use environment variables for configuration settings that change between environments.
• Logging and Monitoring: Implement logging and monitoring for your containerized application to ensure its health and performance in production.

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By completing this project, you will have gained valuable experience in containerizing applications with Docker. This foundational skill is crucial for modern software development and deployment practices.

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