# ┌────────────────────────── build stage ──────────────────────────┐
FROM python:3.11-slim as builder
WORKDIR /app

# install build deps if any (none here), copy requirements
COPY requirements.txt .
RUN pip install --no-cache-dir --upgrade pip \
    && pip install --no-cache-dir -r requirements.txt

# └────────────────────────── final stage ──────────────────────────┘
FROM python:3.11-slim
WORKDIR /app

# copy only installed packages from builder (local pip cache)
COPY --from=builder /usr/local/lib/python3.11/site-packages \
                     /usr/local/lib/python3.11/site-packages
COPY --from=builder /usr/local/bin /usr/local/bin

# copy app code
COPY app.py .

# expose port
EXPOSE 8000

# use a non-root user if you like; for brevity we run as root.

# run via Gunicorn WSGI server with 4 workers
CMD ["gunicorn", "app:app", \
     "--bind", "0.0.0.0:8000", \
     "--workers", "4", \
     "--threads", "4", \
     "--access-logfile", "-", \
     "--error-logfile", "-"]