build only dependencies for a docker layer

[sean-abbott]

Is there a way to build only my dependencies for a multi-stage docker build, without needing my code, and using pyproject.toml only?

I'm managing this with

FROM python:3.12-slim as builder

RUN apt-get update \
    && apt-get -y install build-essential libpq-dev

RUN pip install --upgrade pip --root-user-action=ignore && \
    pip install hatch --root-user-action=ignore

WORKDIR /deps

COPY pyproject.toml /deps
RUN mkdir -p /deps/src && \
    touch /deps/README.md && \
    hatch dep show requirements > requirements.txt

RUN pip install -t dist -r requirements.txt --root-user-action=ignore

# Final Layer
FROM python:3.12-slim

RUN apt-get update \
    && apt-get install -y libpq5 \
    && rm -rf /var/lib/apt/lists/*

WORKDIR /app
COPY --from=builder /deps/dist/ /usr/local/lib/python3.12/site-packages/
COPY --from=builder /deps/dist/bin /usr/local/bin
COPY . /app/

RUN pip install --upgrade pip --root-user-action=ignore && \
    pip install -e . --root-user-action=ignore

ENV PYTHONDONTWRITEBYTECODE=1
ENV PYTHONUNBUFFERED=1

But it would be nice to just be able to do this directly with hatch, and be able to build a wheel that I can explicitly pull from my build stage and just install as a single file.