Dockerfile

FROM python:3.11-slim

# Security & runtime env.
ENV PYTHONDONTWRITEBYTECODE=1 \
    PYTHONUNBUFFERED=1 \
    PIP_NO_CACHE_DIR=1 \
    PIP_DISABLE_PIP_VERSION_CHECK=1

WORKDIR /app

# Install dependencies first for better layer caching.
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

# Copy application source.
COPY . .

# Run as a non-root user (defence in depth — a compromised process is not root).
RUN useradd --create-home --uid 10001 appuser \
    && mkdir -p /app/logs \
    && chown -R appuser:appuser /app
USER appuser

EXPOSE 4000

# Container-level liveness check hitting the app's /health endpoint.
HEALTHCHECK --interval=30s --timeout=5s --start-period=20s --retries=3 \
    CMD python -c "import urllib.request,sys; \
        sys.exit(0) if urllib.request.urlopen('http://127.0.0.1:4000/health').status==200 else sys.exit(1)"

CMD ["uvicorn", "app:app", "--host", "0.0.0.0", "--port", "4000", "--workers", "2"]