# syntax=docker/dockerfile:1.7
#
# Python Multi-Stage Dockerfile with pip (Traditional)
# Features: Layer caching, minimal image, non-root, security hardened
#
# Build args:
#   PYTHON_VERSION - Python version (default: 3.12)
#
# Usage:
#   docker build -t myapp:latest .
#   docker run --rm -p 8000:8000 myapp:latest

# =============================================================================
# Stage 1: Build environment
# =============================================================================
ARG PYTHON_VERSION=3.12

FROM python:${PYTHON_VERSION}-slim AS builder

# Install build dependencies
RUN apt-get update && \
    apt-get install -y --no-install-recommends \
        build-essential \
        gcc && \
    rm -rf /var/lib/apt/lists/*

WORKDIR /app

# Create virtual environment
RUN python -m venv /opt/venv
ENV PATH="/opt/venv/bin:$PATH"

# Install dependencies first (layer caching)
COPY requirements.txt .
RUN --mount=type=cache,target=/root/.cache/pip \
    pip install --no-compile -r requirements.txt

# Copy and install application
COPY . .
RUN --mount=type=cache,target=/root/.cache/pip \
    pip install --no-compile .

# =============================================================================
# Stage 2: Production runtime (minimal)
# =============================================================================
FROM python:${PYTHON_VERSION}-slim AS runtime

# Security: Create non-root user
RUN groupadd --gid 1000 appgroup && \
    useradd --uid 1000 --gid 1000 --shell /bin/false --create-home appuser

# Install runtime dependencies only
RUN apt-get update && \
    apt-get install -y --no-install-recommends \
        ca-certificates \
        tini && \
    apt-get clean && \
    rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

WORKDIR /app

# Copy virtual environment from builder
COPY --from=builder --chown=appuser:appgroup /opt/venv /opt/venv

# Copy application code (if not installed as package)
COPY --from=builder --chown=appuser:appgroup /app /app

# Set environment
ENV PATH="/opt/venv/bin:$PATH" \
    PYTHONDONTWRITEBYTECODE=1 \
    PYTHONUNBUFFERED=1 \
    PYTHONFAULTHANDLER=1

# Security: Switch to non-root user
USER appuser

# Health check
HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \
    CMD python -c "import urllib.request; urllib.request.urlopen('http://localhost:8000/health')" || exit 1

EXPOSE 8000

ENTRYPOINT ["tini", "--"]
CMD ["python", "-m", "app.main"]

# OCI Labels
LABEL org.opencontainers.image.title="My Python App" \
      org.opencontainers.image.description="Python application" \
      org.opencontainers.image.version="1.0.0"