# syntax=docker/dockerfile:1.7

# ============================================================================
# Build stage: install Python dependencies into a dedicated prefix
# ============================================================================
FROM python:3.11-slim-bookworm AS builder

ENV PYTHONDONTWRITEBYTECODE=1 \
    PYTHONUNBUFFERED=1 \
    PIP_NO_CACHE_DIR=1 \
    PIP_DISABLE_PIP_VERSION_CHECK=1

# Install runtime deps into /install. --target keeps everything in one tree
# so we can copy it cleanly to a distroless image without venv/shebang issues.
RUN pip install --target=/install \
      fastapi==0.115.* \
      "uvicorn[standard]==0.30.*" \
      redis==5.0.*

# Pre-compile bytecode for faster cold start under a read-only rootfs
RUN python -m compileall -q /install

# ============================================================================
# Runtime stage: distroless Python 3.11, non-root, no shell
# ============================================================================
# gcr.io/distroless/python3-debian12 ships Python 3.11 with NO shell, NO
# package manager, and NO setuid binaries. The :nonroot tag pins USER to
# uid 65532 / gid 65532.
FROM gcr.io/distroless/python3-debian12:nonroot

ENV PYTHONDONTWRITEBYTECODE=1 \
    PYTHONUNBUFFERED=1 \
    PYTHONPATH=/app/lib

WORKDIR /app

# Site-packages first (rarely changes → maximises layer cache)
COPY --from=builder --chown=nonroot:nonroot /install /app/lib

# Application source (changes most often → its own layer)
COPY --chown=nonroot:nonroot app.py favicon.ico /app/

USER nonroot
EXPOSE 8000

# Module form (-m uvicorn) sidesteps broken shebangs in /app/lib/bin/uvicorn
# (those were generated against the builder's Python path, not distroless's).
ENTRYPOINT ["/usr/bin/python3", "-m", "uvicorn"]
CMD ["app:app", "--host", "0.0.0.0", "--port", "8000"]