Docker Multi Stage

# Node.js Multi-Stage Dockerfile
# Optimized for production with minimal image size

# ============================================
# Stage 1: Dependencies
# ============================================
FROM node:20-alpine AS deps
WORKDIR /app

# Copy package files
COPY package*.json ./

# Install ALL dependencies (including dev)
RUN npm ci

# ============================================
# Stage 2: Builder
# ============================================
FROM node:20-alpine AS builder
WORKDIR /app

# Copy dependencies from deps stage
COPY --from=deps /app/node_modules ./node_modules

# Copy source code
COPY . .

# Build the application
RUN npm run build

# Prune dev dependencies
RUN npm prune --production

# ============================================
# Stage 3: Production
# ============================================
FROM node:20-alpine AS production

# Security: Run as non-root user
RUN addgroup -g 1001 -S nodejs && \
    adduser -S nextjs -u 1001

WORKDIR /app

# Copy only production dependencies
COPY --from=builder --chown=nextjs:nodejs /app/node_modules ./node_modules

# Copy built application
COPY --from=builder --chown=nextjs:nodejs /app/dist ./dist
COPY --from=builder --chown=nextjs:nodejs /app/package.json ./

# Set environment
ENV NODE_ENV=production
ENV PORT=3000

# Switch to non-root user
USER nextjs

# Expose port
EXPOSE 3000

# Health check
HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
  CMD wget --no-verbose --tries=1 --spider http://localhost:3000/health || exit 1

# Start application
CMD ["node", "dist/index.js"]

# ============================================
# Build: docker build -t myapp:prod .
# Run:   docker run -p 3000:3000 myapp:prod
# ============================================


# Python Multi-Stage Dockerfile
# Optimized for production with minimal image size

# ============================================
# Stage 1: Builder
# ============================================
FROM python:3.12-slim AS builder

WORKDIR /app

# Install build dependencies
RUN apt-get update && apt-get install -y --no-install-recommends \
    build-essential \
    && rm -rf /var/lib/apt/lists/*

# Create virtual environment
RUN python -m venv /opt/venv
ENV PATH="/opt/venv/bin:$PATH"

# Install Python dependencies
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

# ============================================
# Stage 2: Production
# ============================================
FROM python:3.12-slim AS production

# Security: Create non-root user
RUN groupadd -r appgroup && useradd -r -g appgroup appuser

WORKDIR /app

# Copy virtual environment from builder
COPY --from=builder /opt/venv /opt/venv
ENV PATH="/opt/venv/bin:$PATH"

# Copy application code
COPY --chown=appuser:appgroup . .

# Remove unnecessary files
RUN rm -rf tests/ docs/ *.md Makefile

# Set environment variables
ENV PYTHONDONTWRITEBYTECODE=1 \
    PYTHONUNBUFFERED=1 \
    PYTHONFAULTHANDLER=1

# Switch to non-root user
USER appuser

# Expose port
EXPOSE 8000

# Health check
HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
  CMD python -c "import urllib.request; urllib.request.urlopen('http://localhost:8000/health')" || exit 1

# Run application
CMD ["python", "-m", "uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000"]

# ============================================
# Build: docker build -t myapp:prod .
# Run:   docker run -p 8000:8000 myapp:prod
# ============================================


# Multi-Stage Build Patterns

## Pattern 1: Build and Production

The most common pattern - build in one stage, run in another.

```dockerfile
# Build stage
FROM node:20 AS builder
WORKDIR /app
COPY . .
RUN npm ci && npm run build

# Production stage
FROM node:20-alpine
COPY --from=builder /app/dist ./dist
CMD ["node", "dist/index.js"]
```

## Pattern 2: Dependency Caching

Separate dependency installation for better caching.

```dockerfile
# Dependencies stage
FROM node:20-alpine AS deps
C