[🍑 Beginner Q] Can I use UV for a Shiny App

[michellepace]

Hello there.

I have just discovered Shiny for Python. I am just a little confused on how Package management works within Shiny. As a beginner I am only familiar with UV as my Python package and project manager. Has Shiny got any inbuilt capabilities or is it advantageous to still (somehow) use UV in combination?

Q1. If the answer is yes, please could you tell me the steps to initialise a new Shiny project so it uses UV.

Q2. If there is any relevant documentation I missed, please do let me know.

Thanks in advance,
Michelle

[cpsievert]

Hi @michellepace -- you can absolutely use uv as your package manager with Shiny. We list it here as an option on the installation page (although, we should probably consider making it the default option):

https://shiny.posit.co/py/get-started/install.html

[michellepace]

Hello @cpsievert

Thank you, I’m sorry to ask again but I remain confused - I’ve never used pip with UV before and never had a requirements.txt file only pyproject.toml.

In place of this as per the docs: uv pip install shiny

To create a new project, is this the right way:

uv init my-shiny-app
cd my-shiny-app
uv add shiny              # NOT uv pip install shiny
uv run shiny create
uv run shiny run app.py --reload

I basically just need Shiny to be properly setup and using UV. I’m a novice Python / UV user which is most likely the reason for my confusion.

Looking forward to your reply. And thanks again.

Michelle

[gadenbuie]

To create a new project, is this the right way:

Totally! I do this all the time 😄

[michellepace]

Okay super, let me know if I can update Shiny documentation? It’s strange to say pip with UV… well I thought that was the point of UV - not to be using pip.

I’ve just got Grok to explain it too, is it correct, as in best remove main.py @gadenbuie? Again sorry for the basic questions.

# Create and initialize the project directory with pyproject.toml
uv init my-shiny-app

# Navigate into the directory
cd my-shiny-app

# Optional but recommended: Remove the default main.py to avoid unnecessary files
rm main.py  # Or del main.py on Windows

# Add Shiny as a dependency (this updates pyproject.toml, creates .venv if needed, installs Shiny, and generates uv.lock)
uv add shiny

# Generate the Shiny app boilerplate in the current directory using the Shiny CLI (runs in the project environment)
uv run shiny create

# Run the app (assumes shiny create generated app.py; use --reload for development auto-reloading)
uv run shiny run app.py --reload

I’ll just leave this here to remind myself in the mean time.

[gadenbuie]

Yeah, you can use uv init --bare my-shiny-app to initialize with just a pyproject.toml and without the main.py.

uv pip install is perfectly fine and has been around for a while; it was one of the earliest use-cases of uv. uv opens up a few use cases

• uv pip install for same workflow long-time Python users are used to
• uv init for a nice "start a project" approach
• uv init --script app.py for a standalone Shiny app as a single file (followed up with uv add --script app.py shiny)