Getting uv right inside Docker is a bit tricky and even their official recommendations are not optimal.

It is better to use a two-step build process to eliminate uv from the final image size.

A two-step build process not only saves disk space but also reduces attack surface against security vulerabilities

EDIT: See my solution in the comments!

I've loved uv's local DevEx until now, but I can't seem to find the "recommended"/"best" way to create a docker image that installs all my dependencies system-wide (without a venv) in a Docker image.

I've tried with a 'pyproject.toml' (and associated 'uv.lock'):

[project]
name = "api"
version = "0.1.0"
description = "Add your description here"
readme = "README.md"
requires-python = ">=3.13"
dependencies = [
    "fastapi>=0.115.6", 
    etc...
]

[dependency-groups]
dev = [
    "pytest>=8.3.4",
    etc...
]

And a Dockerfile:

FROM ghcr.io/astral-sh/uv:python3.13-alpine

#ENV UV_PROJECT_ENVIRONMENT="/usr/local/bin/" TODO ???
ENV PYTHONUNBUFFERED True

WORKDIR /app
COPY . .
RUN uv sync --locked --python-preference system --no-dev

BUT exec'ing into the image after build, I see no '.venv/' and:

/app # python main.py 
Traceback (most recent call last):
  File "/app/main.py", line 1, in <module>
    from fastapi import FastAPI
ModuleNotFoundError: No module named 'fastapi'

• Should I be using uv install --system... instead or is that deprecated?

• Should I use UV_PROJECT_ENVIRONMENT?

• Should I simply run everything within a venv inside containers somehow?

Any help or suggestions is greatly appreciated!!