Dockerfile

# Multi-stage build for production - Optimized for React artifacts
FROM public.ecr.aws/docker/library/node:24-alpine AS frontend-builder

WORKDIR /app/frontend

# Stage 1: Install dependencies (cached separately for faster rebuilds)
COPY frontend/package*.json ./
RUN npm ci --omit=dev --legacy-peer-deps

# Stage 2: Copy source and build (changes to source don't invalidate npm layer)
COPY frontend/src ./src
COPY frontend/public ./public

# Build frontend with production optimizations
# CI=true prevents interactive mode, GENERATE_SOURCEMAP=false reduces build time
# COMPRESS_LEVEL=9 enables maximum compression for static assets
ENV NODE_ENV=production
ENV CI=true
ENV GENERATE_SOURCEMAP=false
ENV REACT_APP_PRODUCTION=true
RUN npm run build

# Optional: Verify build output size
RUN du -sh build/ && ls -lah build/static/js/ && ls -lah build/static/css/

# Production stage
FROM public.ecr.aws/docker/library/python:3.14-slim

WORKDIR /app

# Production Python environment variables
ENV PYTHONDONTWRITEBYTECODE=1 \
    PYTHONUNBUFFERED=1 \
    PYTHONOPTIMIZE=2

# Copy requirements and install Python dependencies with caching (before user creation for better layer reuse)
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt && \
    pip cache purge

# Create non-root user with minimal privileges
RUN groupadd --gid 1000 -r appgroup && \
    useradd -r --uid 1000 --gid appgroup -d /app appuser && \
    mkdir -p /app/.aws/sso/cache && \
    chown -R appuser:appgroup /app

# Copy application code and entrypoint script
COPY --chown=appuser:appgroup app.py .
COPY --chown=appuser:appgroup entrypoint.sh .

# Make entrypoint executable
RUN chmod +x entrypoint.sh

# Copy built frontend from builder stage (optimized artifacts only)
# Note: build/ contains minified JS/CSS with hashed filenames for long-term caching
COPY --chown=appuser:appgroup --from=frontend-builder /app/frontend/build ./frontend/build

# Switch to non-root user
USER appuser

# Expose port
EXPOSE 5000

# Set Flask-specific production environment variables
ENV FLASK_ENV=production \
    FLASK_DEBUG=False

# Health check for orchestration
HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
  CMD python -c "import urllib.request; urllib.request.urlopen('http://localhost:5000/api/health')" || exit 1

# Run with gunicorn for production
# Settings optimized for AWS environment:
# - workers: 4 (suitable for 1-2 CPU, increase for larger instances)
# - worker-class: gthread (concurrent I/O with threads, better than sync for AWS API calls)
# - threads: 2 per worker (4 workers × 2 threads = 8 concurrent requests)
# - preload-app: load Flask app once, share across workers (memory efficient)
# - max-requests: recycle workers to prevent memory creep from long-running AWS calls
# - timeout: 120s (for large subnet API calls)
# - graceful-timeout: 30s (clean shutdown window)
# - keep-alive: 2s (shorter for unpredictable AWS latency)
ENTRYPOINT ["/app/entrypoint.sh"]
CMD ["gunicorn", \
     "--bind", "0.0.0.0:5000", \
     "--workers", "4", \
     "--worker-class", "gthread", \
     "--threads", "2", \
     "--max-requests", "1000", \
     "--max-requests-jitter", "100", \
     "--preload", \
     "--timeout", "120", \
     "--graceful-timeout", "30", \
     "--keep-alive", "2", \
     "--error-logfile", "-", \
     "--access-logfile", "-", \
     "--log-level", "info", \
     "app:app"]