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 app code
COPY app.py .

EXPOSE 5000

# Basic container-level health check (Docker/most platforms respect this)
HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
  CMD python -c "import urllib.request; urllib.request.urlopen('http://localhost:5000/health')" || exit 1

# gunicorn for production-grade serving instead of Flask dev server
CMD ["gunicorn", "--bind", "0.0.0.0:5000", "--workers", "2", "app:app"]