Note: There are tags for each build date. If you need to "pin" the Docker image version you use, you can select one of those tags. E.g. tiangolo/uvicorn-gunicorn-fastapi:python3.11-2024-11-02.

uvicorn-gunicorn-fastapi

Docker image with Uvicorn managed by Gunicorn for high-performance FastAPI web applications in Python with performance auto-tuning.

GitHub repo: https://github.com/tiangolo/uvicorn-gunicorn-fastapi-docker

Docker Hub image: https://hub.docker.com/r/tiangolo/uvicorn-gunicorn-fastapi/

Description

FastAPI has shown to be a Python web framework with one of the best performances, as measured by third-party benchmarks, thanks to being based on and powered by Starlette.

The achievable performance is on par with (and in many cases superior to) Go and Node.js frameworks.

This image has an auto-tuning mechanism included to start a number of worker processes based on the available CPU cores. That way you can just add your code and get high performance automatically, which is useful in simple deployments.

🚨 WARNING: You Probably Don't Need this Docker Image

You are probably using Kubernetes or similar tools. In that case, you probably don't need this image (or any other similar base image). You are probably better off building a Docker image from scratch as explained in the docs for FastAPI in Containers - Docker: Build a Docker Image for FastAPI.

Cluster Replication

If you have a cluster of machines with Kubernetes, Docker Swarm Mode, Nomad, or other similar complex system to manage distributed containers on multiple machines, then you will probably want to handle replication at the cluster level instead of using a process manager (like Gunicorn with Uvicorn workers) in each container, which is what this Docker image does.

In those cases (e.g. using Kubernetes) you would probably want to build a Docker image from scratch, installing your dependencies, and running a single Uvicorn process instead of this image.

For example, your Dockerfile could look like:

FROM python:3.11

WORKDIR /code

COPY ./requirements.txt /code/requirements.txt

RUN pip install --no-cache-dir --upgrade -r /code/requirements.txt

COPY ./app /code/app

CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "80"]

You can read more about this in the FastAPI documentation about: FastAPI in Containers - Docker.

Multiple Workers

If you definitely want to have multiple workers on a single container, Uvicorn now supports handling subprocesses, including restarting dead ones. So there's no need for Gunicorn to manage multiple workers in a single container.

You could modify the example Dockerfile from above, adding the --workers option to Uvicorn, like:

FROM python:3.11

WORKDIR /code

COPY ./requirements.txt /code/requirements.txt

RUN pip install --no-cache-dir --upgrade -r /code/requirements.txt

COPY ./app /code/app

CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "80", "--workers", "4"]

That's all you need. You don't need this Docker image at all. 😅

You can read more about it in the FastAPI Docs about Deployment with Docker.

Technical Details

Uvicorn didn't have support for managing worker processing including restarting dead workers. But now it does.

Before that, Gunicorn could be used as a process manager, running Uvicorn workers. This added complexity that is no longer necessary.

Legacy Docs

The rest of this document is kept for historical reasons, but you probably don't need it. 😅

tiangolo/uvicorn-gunicorn-fastapi

This image will set a sensible configuration based on the server it is running on (the amount of CPU cores available) without making sacrifices.

It has sensible defaults, but you can configure it with environment variables or override the configuration files.

There are also slim versions. If you want one of those, use one of the tags from above.

tiangolo/uvicorn-gunicorn

This image (tiangolo/uvicorn-gunicorn-fastapi) is based on tiangolo/uvicorn-gunicorn.

That image is what actually does all the work.

This image just installs FastAPI and has the documentation specifically targeted at FastAPI.

If you feel confident about your knowledge of Uvicorn, Gunicorn and ASGI, you can use that image directly.

tiangolo/uvicorn-gunicorn-starlette

There is a sibling Docker image: tiangolo/uvicorn-gunicorn-starlette

If you are creating a new Starlette web application and you want to discard all the additional features from FastAPI you should use tiangolo/uvicorn-gunicorn-starlette instead.

Note: FastAPI is based on Starlette and adds several features on top of it. Useful for APIs and other cases: data validation, data conversion, documentation with OpenAPI, dependency injection, security/authentication and others.

How to use

You don't need to clone the GitHub repo.

You can use this image as a base image for other images.

Assuming you have a file requirements.txt, you could have a Dockerfile like this:

FROM tiangolo/uvicorn-gunicorn-fastapi:python3.11

COPY ./requirements.txt /app/requirements.txt

RUN pip install --no-cache-dir --upgrade -r /app/requirements.txt

COPY ./app /app

It will expect a file at /app/app/main.py.

Or otherwise a file at /app/main.py.

And will expect it to contain a variable app with your FastAPI application.

Then you can build your image from the directory that has your Dockerfile, e.g:

docker build -t myimage ./

Quick Start

Build your Image

• Go to your project directory.
• Create a Dockerfile with:

FROM tiangolo/uvicorn-gunicorn-fastapi:python3.11

COPY ./requirements.txt /app/requirements.txt

RUN pip install --no-cache-dir --upgrade -r /app/requirements.txt

COPY ./app /app

• Create an app directory and enter in it.
• Create a main.py file with:

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: str = None):
    return {"item_id": item_id, "q": q}

• You should now have a directory structure like:

.
├── app
│   └── main.py
└── Dockerfile

• Go to the project directory (in where your Dockerfile is, containing your app directory).
• Build your FastAPI image:

docker build -t myimage .

• Run a container based on your image:

docker run -d --name mycontainer -p 80:80 myimage

Now you have an optimized FastAPI server in a Docker container. Auto-tuned for your current server (and number of CPU cores).

Check it

You should be able to check it in your Docker container's URL, for example: http://192.168.99.100/items/5?q=somequery or http://127.0.0.1/items/5?q=somequery (or equivalent, using your Docker host).

You will see something like:

{"item_id": 5, "q": "somequery"}

Interactive API docs

Now you can go to http://192.168.99.100/docs or http://127.0.0.1/docs (or equivalent, using your Docker host).

You will see the automatic interactive API documentation (provided by Swagger UI):

Alternative API docs

And you can also go to http://192.168.99.100/redoc or http://127.0.0.1/redoc(or equivalent, using your Docker host).

You will see the alternative automatic documentation (provided by ReDoc):

Dependencies and packages

You will probably also want to add any dependencies for your app and pin them to a specific version, probably including Uvicorn, Gunicorn, and FastAPI.

This way you can make sure your app always works as expected.

You could install packages with pip commands in your Dockerfile, using a requirements.txt, or even using Poetry.

And then you can upgrade those dependencies in a controlled way, running your tests, making sure that everything works, but without breaking your production application if some new version is not compatible.

Using Poetry

Here's a small example of one of the ways you could install your dependencies making sure you have a pinned version for each package.

Let's say you have a project managed with Poetry, so, you have your package dependencies in a file pyproject.toml. And possibly a file poetry.lock.

Then you could have a Dockerfile using Do