Dockerfile

# ─────────────── builder stage ───────────────
FROM python:3.9-slim AS builder
WORKDIR /build

# app + deps
COPY requirements.txt .
RUN pip install --prefix=/install --no-cache-dir -r requirements.txt
COPY app.py .

# compile to plain app.pyc in the same dir
RUN python -m compileall -b -f app.py   # → /build/app.pyc

# ─────────────── runtime stage ───────────────
FROM python:3.9-slim
WORKDIR /app

# 1) bring the site-packages that were installed into /install
COPY --from=builder /install /usr/local/

# 2) copy only the compiled byte-code
COPY --from=builder /build/app.pyc ./app.pyc

# 3) nothing else to see — no source
ENTRYPOINT ["python", "/app/app.pyc"]