Dockerfile

# ──────────────────────────────────────────────────────────────────────
# Stage 1: Build
# ──────────────────────────────────────────────────────────────────────
FROM node:18-alpine AS builder

# Set working directory
WORKDIR /app

# Copy package files
COPY package*.json ./

# Install dependencies
RUN npm ci --only=production

# ──────────────────────────────────────────────────────────────────────
# Stage 2: Production
# ──────────────────────────────────────────────────────────────────────
FROM node:18-alpine

# Create app user (don't run as root)
RUN addgroup -g 1001 -S nodejs && \
    adduser -S nodejs -u 1001

# Set working directory
WORKDIR /app

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

# Copy application code
COPY --chown=nodejs:nodejs . .

# Switch to non-root user
USER nodejs

# Expose port
EXPOSE 3000

# Health check
HEALTHCHECK --interval=30s --timeout=3s --start-period=40s --retries=3 \
  CMD node healthcheck.js || exit 1

# Start application
CMD ["node", "-r", "esm", "index.js"]