Building docker image and then switching to non root user

[adiberk]

My company does a two part build process in the docker image
We first install dependencies and then we build the image using a non root user

When using poetry we just copy the .venv folder to the new workdir in the image creation step and everything works fine. However when I do this with UV and run the app, I was getting issues bash: line 1: /app/.venv/bin/uvicorn: cannot execute: required file not found even though they are 100% there. After reviewing further I see it might be a symlink issue pointing to a path in first build that doesn't exist in second build. I tried setting link-mode to copy, but I assume the core issue here is I lack an understanding of what is really going on here.
Any advice would be greatly appreciated!
(WE do 2 part built for slight speed improvements, but isn't 100% necessary - seeing if we can just do it all in one go)

Here is a slimmed down version of what we are doing (using UV)

FROM python:3.11.4-bookworm AS build
ARG ENV

COPY --from=ghcr.io/astral-sh/uv:0.4.17 /uv /bin/uv

# SET ENV
ENV LIBRARY_PATH=/lib:/usr/lib

# Prepare install
WORKDIR /app
COPY pyproject.toml uv.lock ./

RUN uv sync --frozen --no-install-project

# Run second stage of build
FROM python:3.11.4-slim

RUN useradd --create-home appuser

# create /app directory and chown to to node user or else it will be owned by root
RUN mkdir -p /app && chown appuser:appuser /app
WORKDIR /app

ENV LIBRARY_PATH=/lib:/usr/lib

# Copy files from build stage
COPY --chown=appuser:appuser --from=build /app/.venv /app/.venv

COPY --chown=appuser:appuser . /app

ENV VIRTUAL_ENV=/app/.venv
ENV PATH="/app/.venv/bin:$PATH"

ENV PYTHONHASHSEED=0
USER lev