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What Are Docker Containers?

Docker containers are lightweight, standalone, executable packages that include everything needed to run an application: code, runtime, system tools, libraries, and settings.

Why Use Docker for Web Development?

Consistency: “It works on my machine” becomes “It works on every machine”
Isolation: Dependencies for different projects don’t conflict
Simplified setup: New team members can get started quickly
Environment parity: Development environments match production

Basic Docker Commands

Here are some essential Docker commands to get started:

# Pull an image from Docker Hub
docker pull node:18

# Run a container
docker run -p 3000:3000 -v $(pwd):/app node:18

# List running containers
docker ps

# Stop a container
docker stop container_id

# Remove a container
docker rm container_id

Creating a Dockerfile

A Dockerfile defines how to build your application’s container:

# Use Node.js as the base image
FROM node:18-alpine

# Set working directory
WORKDIR /app

# Copy package files
COPY package*.json ./

# Install dependencies
RUN npm install

# Copy application code
COPY . .

# Expose port
EXPOSE 3000

# Start the application
CMD ["npm", "start"]

Docker Compose for Multi-Container Apps

For applications with multiple services (frontend, backend, database), Docker Compose simplifies management:

# docker-compose.yml
version: '3'
services:
  frontend:
    build: ./frontend
    ports:
      - "3000:3000"
    depends_on:
      - backend

  backend:
    build: ./backend
    ports:
      - "4000:4000"
    depends_on:
      - database

  database:
    image: postgres:14
    environment:
      POSTGRES_PASSWORD: example

Conclusion