I'm well aware of `COPY --link`, it doesn't solve the problem. I'm a heavy heavy user of it, combined with throwaway build stages. `COPY --link` won't help my `apt install` commands.
The use case here isn't `FROM python:3.10`, it's `FROM ubuntu; RUN apt install -y vim wget curl software-properties-common python3.10`/`RUN rosdep install`/`RUN --mount=type=cache,target=/root/.cache/uv --mount=type=bind,source=uv.lock,target=uv.lock --mount=type=bind,source=pyproject.toml,target=pyproject.toml uv sync --locked --no-install-project`. All of those dependencies get merged onto a single layer that isn't shared with anything else. You'd better hope something like tensorflow isn't one of those dependencies.
Meta: I think your example code would benefit from being a code block; in HN this is done by prefixing with 2 spaces.
eg.
FROM ubuntu
RUN apt install -y vim wget curl software-properties-common python3.10
RUN rosdep install
RUN --mount=type=cache,target=/root/.cache/uv --mount=type=bind,source=uv.lock,target=uv.lock --mount=type=bind,source=pyproject.toml,target=pyproject.toml uv sync --locked --no-install-project
The use case here isn't `FROM python:3.10`, it's `FROM ubuntu; RUN apt install -y vim wget curl software-properties-common python3.10`/`RUN rosdep install`/`RUN --mount=type=cache,target=/root/.cache/uv --mount=type=bind,source=uv.lock,target=uv.lock --mount=type=bind,source=pyproject.toml,target=pyproject.toml uv sync --locked --no-install-project`. All of those dependencies get merged onto a single layer that isn't shared with anything else. You'd better hope something like tensorflow isn't one of those dependencies.