uv/docs/guides/integration/fastapi.md

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](https://github.com/astral-sh/uv-fastapi-example) repository.

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

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

To migrate this project to uv, add a pyproject.toml file to the root directory of the project with uv init:

$ uv init
$ uv add fastapi --extra standard

!!! tip

If you have an existing `pyproject.toml`, `uv init` cannot be used — but you may not need to
make any changes to the file.

You should now have the following structure:

.
├── 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:

[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.

Initializing a FastAPI project

We could reach a similar result to the above by creating a project from scratch with uv init and installing FastAPI with uv add fastapi, as in:

$ uv init app
$ cd app
$ uv add fastapi --extra standard

By default, uv uses a src layout for newly-created projects, so the app directory will be nested within a src directory. If you copied over the source code from the FastAPI tutorial, the project structure would look like this:

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

In this case, you would run the FastAPI application with:

$ uv run fastapi dev src/app/main.py

Deployment

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

FROM python:3.12-slim

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

# 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"]

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