Docker Learning Project

This project demonstrates Docker best practices with a simple multi-container application using Docker Compose. The application consists of three containers:

1. Frontend: A simple Nginx web server serving static HTML, CSS, and JavaScript
2. Backend: A Node.js/Express API server
3. Database: A PostgreSQL database for data persistence

The focus of this project is on Docker concepts rather than complex application logic.

Key Docker Concepts Covered

• Multi-stage Dockerfile builds
• Docker Compose for multi-container orchestration
• Volume management for data persistence
• Container networking
• Environment variables and secrets management
• Docker best practices

Project Structure

docker-learning-project/
├── docker-compose.yml      # Define and configure all services
├── .env                    # Environment variables for docker-compose
├── README.md               # Main project documentation
├── frontend/               # Nginx static web server
├── backend/                # Node.js API server
└── database/               # PostgreSQL database

Getting Started

1. Clone this repository
2. Make sure Docker and Docker Compose are installed
3. Run docker-compose up -d
4. Access the application at http://localhost:8080

Application Functionality

The application is a simple message board where users can:

• View all messages
• Add new messages

This simplicity allows us to focus on Docker concepts rather than complex application logic.

Docker Concepts Explained

Docker Containers

Containers are lightweight, standalone, executable packages that include everything needed to run an application. In this project, we have three containers that work together but remain isolated from each other.

Docker Images

Docker images are read-only templates used to create containers. Each component has its own Dockerfile that defines how to build its image.

Docker Volumes

Volumes are used for data persistence. We use volumes for:

• PostgreSQL data: ensures messages are preserved even if the container is removed
• Backend logs: preserves log data across container restarts

Docker Networking

Containers communicate with each other through Docker networks. We use:

• frontend-network: connects the frontend and backend
• backend-network: connects the backend and database

Environment Variables

Environment variables are used to configure containers without modifying their code. We use a .env file and pass variables through Docker Compose.

Docker Compose

Docker Compose is a tool for defining and running multi-container Docker applications. Our docker-compose.yml file defines all three services and their relationships.