Docker for Developers - From Zero to Production

Your App + Runtime + Libraries + Config
         = Docker Image
              ↓ run
         Docker Container

# Install Docker Desktop (Mac/Windows/Linux)
# https://www.docker.com/products/docker-desktop

# Verify
docker --version
docker run hello-world

# Start from an official Node.js image
FROM node:20-alpine

# Set working directory inside container
WORKDIR /app

# Copy package files FIRST (for layer caching)
COPY package*.json ./

# Install dependencies
RUN npm ci --only=production

# Copy the rest of the code
COPY . .

# Expose the port the app runs on
EXPOSE 3000

# Command to run the app
CMD ["node", "src/index.js"]

# Build the image
docker build -t my-node-app .

# Run the container
docker run -p 3000:3000 my-node-app

# Run in background (detached)
docker run -d -p 3000:3000 --name my-app my-node-app

FROM python:3.12-slim

WORKDIR /app

# Install dependencies first (layer caching)
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

COPY . .

EXPOSE 8000

CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000"]

# Images
docker images                     # List all images
docker pull node:20                # Download an image
docker build -t my-app .           # Build from Dockerfile
docker rmi my-app                  # Remove an image

# Containers
docker ps                          # List running containers
docker ps -a                       # List all containers
docker run -p 3000:3000 my-app     # Run a container
docker start/stop/restart my-app   # Control a container
docker rm my-app                   # Remove a container
docker logs my-app                 # View logs
docker logs -f my-app              # Follow logs in real-time

# Exec — run commands inside container
docker exec -it my-app sh          # Open a shell inside container
docker exec my-app npm run migrate # Run a command

# Cleanup
docker system prune                # Remove unused resources
docker volume prune                # Remove unused volumes

version: '3.9'

services:
  # Your Node.js API
  api:
    build: .
    ports:
      - '3000:3000'
    environment:
      NODE_ENV: development
      DATABASE_URL: postgresql://user:password@db:5432/mydb
      REDIS_URL: redis://redis:6379
    volumes:
      - .:/app           # Mount code for hot reload
      - /app/node_modules
    depends_on:
      - db
      - redis
    restart: unless-stopped

  # PostgreSQL database
  db:
    image: postgres:16-alpine
    environment:
      POSTGRES_USER: user
      POSTGRES_PASSWORD: password
      POSTGRES_DB: mydb
    volumes:
      - postgres_data:/var/lib/postgresql/data
    ports:
      - '5432:5432'

  # Redis cache
  redis:
    image: redis:7-alpine
    ports:
      - '6379:6379'

volumes:
  postgres_data:

# Start all services
docker compose up

# Start in background
docker compose up -d

# Stop all services
docker compose down

# View logs for a service
docker compose logs api

# Rebuild after code changes
docker compose up --build

NODE_ENV=development
DATABASE_URL=postgresql://user:pass@localhost:5432/mydb
JWT_SECRET=your-secret-key

services:
  api:
    env_file:
      - .env  # Load all variables from .env

# Stage 1: Build
FROM node:20-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build  # TypeScript compile

# Stage 2: Production (much smaller!)
FROM node:20-alpine AS production
WORKDIR /app
COPY package*.json ./
RUN npm ci --only=production
COPY --from=builder /app/dist ./dist  # Only copy built files

EXPOSE 3000
CMD ["node", "dist/index.js"]

node_modules
npm-debug.log
.git
.env
.env.local
dist
coverage
*.md
Dockerfile
docker-compose.yml

HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \
  CMD curl -f http://localhost:3000/health || exit 1