Docker for Beginners: Containerize Your First Application

dockerfile
# Use official Node.js image as base
FROM node:20-alpine

# Set working directory inside the container
WORKDIR /app

# Copy package files first (for better caching)
COPY package*.json ./

# Install dependencies
RUN npm ci --only=production

# Copy application code
COPY . .

# Expose port
EXPOSE 3000

# Define the command to run
CMD ["node", "server.js"]

bash
# Build the image
docker build -t my-app:1.0 .

# Run the container
docker run -d -p 3000:3000 --name my-app my-app:1.0

# Check running containers
docker ps

# View logs
docker logs my-app

# Stop the container
docker stop my-app

yaml
# docker-compose.yml
version: '3.8'

services:
  app:
    build: .
    ports:
      - "3000:3000"
    environment:
      - MONGODB_URI=mongodb://mongo:27017/mydb
      - REDIS_URL=redis://redis:6379
    depends_on:
      - mongo
      - redis

  mongo:
    image: mongo:7
    volumes:
      - mongo-data:/data/db
    ports:
      - "27017:27017"

  redis:
    image: redis:7-alpine
    ports:
      - "6379:6379"

volumes:
  mongo-data:

bash
# Start all services
docker-compose up -d

# Stop all services
docker-compose down

# View logs for a specific service
docker-compose logs -f app

node_modules
.git
.env
*.md
docker-compose*.yml
.dockerignore
Dockerfile