Dockerfile

# =============================================================================
# Dockerfile for coding-drills Next.js Application
# Multi-stage build optimized for production
# =============================================================================

# -----------------------------------------------------------------------------
# Stage 1: Dependencies
# Install production and dev dependencies with pnpm
# -----------------------------------------------------------------------------
FROM node:20-alpine AS deps

# Install pnpm
RUN corepack enable && corepack prepare pnpm@9 --activate

WORKDIR /app

# Copy package files for dependency installation
COPY package.json pnpm-lock.yaml ./

# Install all dependencies (including devDependencies for build)
RUN pnpm install --frozen-lockfile

# -----------------------------------------------------------------------------
# Stage 2: Builder
# Build the Next.js application
# -----------------------------------------------------------------------------
FROM node:20-alpine AS builder

# Install pnpm
RUN corepack enable && corepack prepare pnpm@9 --activate

WORKDIR /app

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

# Copy source code
COPY . .

# Set environment variables for build
ENV NEXT_TELEMETRY_DISABLED=1
ENV NODE_ENV=production

# Build the application
RUN pnpm build

# -----------------------------------------------------------------------------
# Stage 3: Runner
# Production runtime with minimal footprint
# -----------------------------------------------------------------------------
FROM node:20-alpine AS runner

WORKDIR /app

# Set environment variables
ENV NODE_ENV=production
ENV NEXT_TELEMETRY_DISABLED=1
ENV PORT=3000
ENV HOSTNAME="0.0.0.0"

# Create non-root user for security
RUN addgroup --system --gid 1001 nodejs && \
    adduser --system --uid 1001 nextjs

# Copy public assets
COPY --from=builder /app/public ./public

# Copy Next.js build output
# Automatically leverage output traces to reduce image size
# https://nextjs.org/docs/advanced-features/output-file-tracing
COPY --from=builder --chown=nextjs:nodejs /app/.next/standalone ./
COPY --from=builder --chown=nextjs:nodejs /app/.next/static ./.next/static

# Switch to non-root user
USER nextjs

# Expose the application port
EXPOSE 3000

# Health check
HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \
    CMD wget --no-verbose --tries=1 --spider http://localhost:3000/ || exit 1

# Start the application
CMD ["node", "server.js"]