FastAPI

Using uv with FastAPI

FastAPI is a modern, high-performance Python web framework. You can use uv to manage your FastAPI project, including installing dependencies, managing environments, running FastAPI applications, and more.

Note

You can view the source code for this guide in the uv-fastapi-example repository.

Migrating an existing FastAPI project

As an example, consider the sample application defined in the FastAPI documentation, structured as follows:

project
└── app
    ├── __init__.py
    ├── main.py
    ├── dependencies.py
    ├── routers
    │   ├── __init__.py
    │   ├── items.py
    │   └── users.py
    └── internal
        ├── __init__.py
        └── admin.py

To use uv with this application, inside the project directory run:

$ uv init --app

This creates a project with an application layout and a pyproject.toml file.

Then, add a dependency on FastAPI:

$ uv add fastapi --extra standard

You should now have the following structure:

project
├── pyproject.toml
└── app
    ├── __init__.py
    ├── main.py
    ├── dependencies.py
    ├── routers
    │   ├── __init__.py
    │   ├── items.py
    │   └── users.py
    └── internal
        ├── __init__.py
        └── admin.py

And the contents of the pyproject.toml file should look something like this:

pyproject.toml

[project]
name = "uv-fastapi-example"
version = "0.1.0"
description = "FastAPI project"
readme = "README.md"
requires-python = ">=3.12"
dependencies = [
    "fastapi[standard]",
]

From there, you can run the FastAPI application with:

$ uv run fastapi dev

uv run will automatically resolve and lock the project dependencies (i.e., create a uv.lock alongside the pyproject.toml), create a virtual environment, and run the command in that environment.

Test the app by opening <http://127.0.0.1:8000/?token=jessica> in a web browser.

Deployment

To deploy the FastAPI application with Docker, you can use the following Dockerfile:

Dockerfile

FROM python:3.12-slim

## Install uv.
COPY --from=ghcr.io/astral-sh/uv:latest /uv /uvx /bin/

## Copy the application into the container.
COPY . /app

## Install the application dependencies.
WORKDIR /app
RUN uv sync --frozen --no-cache

## Run the application.
CMD ["/app/.venv/bin/fastapi", "run", "app/main.py", "--port", "80", "--host", "0.0.0.0"]

Build the Docker image with:

$ docker build -t fastapi-app .

Run the Docker container locally with:

$ docker run -p 8000:80 fastapi-app

Navigate to <http://127.0.0.1:8000/?token=jessica> in your browser to verify that the app is running correctly.

Tip

For more on using uv with Docker, see the Docker guide.

April 15, 2025