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⁠DEPRECATED 🚨

This Docker image is now deprecated. Read about it below.

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⁠Supported tags and respective Dockerfile links

⁠Deprecated tags

🚨 These tags are no longer supported or maintained, they are removed from the GitHub repository, but the last versions pushed might still be available in Docker Hub if anyone has been pulling them:

  • python3.9
  • python3.8
  • python3.8-alpine
  • python3.7
  • python3.6
  • python2.7

The last date tags for these versions are:

    • python3.9-2025-11-09
  • python3.8-2024-10-28
  • python3.8-alpine-2024-03-11
  • python3.7-2024-10-28
  • python3.6-2022-11-25
  • python2.7-2022-11-25

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/uwsgi-nginx-flask:python3.7-2019-10-14.

⁠uwsgi-nginx-flask

Docker image with uWSGI and Nginx for Flask web applications in Python running in a single container.

⁠Description

This Docker⁠ image allows you to create Flask⁠ web applications in Python⁠ that run with uWSGI⁠ and Nginx⁠ in a single container.

The combination of uWSGI with Nginx is a common way to deploy Python Flask web applications⁠.

GitHub repo: https://github.com/tiangolo/uwsgi-nginx-flask-docker⁠

Docker Hub image: https://hub.docker.com/r/tiangolo/uwsgi-nginx-flask/⁠

⁠🚨 DEPRECATION WARNING

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.

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 in each container that starts multiple worker processes, 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 process instead of this image.

For example, using Gunicorn⁠ you could have a file app/gunicorn_conf.py with:

# Gunicorn config variables
loglevel = "info"
errorlog = "-"  # stderr
accesslog = "-"  # stdout
worker_tmp_dir = "/dev/shm"
graceful_timeout = 120
timeout = 120
keepalive = 5
threads = 3

And then you could have a Dockerfile with:

FROM python:3.12
WORKDIR /code
COPY ./requirements.txt /code/requirements.txt
RUN pip install --no-cache-dir --upgrade -r /code/requirements.txt
COPY ./app /code/app
CMD ["gunicorn", "--conf", "app/gunicorn_conf.py", "--bind", "0.0.0.0:80", "app.main:app"]

You can read more about these ideas in the FastAPI documentation about: FastAPI in Containers - Docker⁠ as the same ideas would apply to other web applications in containers.

uWSGI is now in maintenance mode⁠, so it's probably better to migrate to a different tool.

Additionally, I haven't used this Docker image in years, so I don't have much bandwidth to keep it up to date. Most of my time is dedicated to FastAPI⁠ and friends.

You can probably still use this image as-is, while you migrate to a different tool, but I won't be adding (and maintaining) support for new versions of Python.

⁠Historical Docs

The rest of the README is preserved mainly for historical reasons.

⁠General Instructions

You don't have to clone this 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/uwsgi-nginx-flask:python3.12
COPY ./requirements.txt /app/requirements.txt
RUN pip install --no-cache-dir --upgrade -r /app/requirements.txt
COPY ./app /app

There are several image tags available but for new projects you should use the latest version available.

This Docker image is based on tiangolo/uwsgi-nginx⁠. That Docker image has uWSGI and Nginx installed in the same container and was made to be the base of this image.

⁠Quick Start

  • Go to your project directory
  • Create a Dockerfile with:
FROM tiangolo/uwsgi-nginx-flask:python3.12
COPY ./app /app
  • Create an app directory and enter in it
  • Create a main.py file (it should be named like that and should be in your app directory) with:
from flask import Flask
app = Flask(__name__)
@app.route("/")
def hello():
    return "Hello World from Flask"
if __name__ == "__main__":
    # Only for debugging while developing
    app.run(host='0.0.0.0', debug=True, port=80)

the main application object should be named app (in the code) as in this example.

Note: The section with the main() function is for debugging purposes. To learn more, read the Advanced instructions below.

  • 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 Flask image:
docker build -t myimage .
  • Run a container based on your image:
docker run -d --name mycontainer -p 80:80 myimage

...and you have an optimized Flask server in a Docker container.

You should be able to check it in your Docker container's URL, for example: http://192.168.99.100⁠ or http://127.0.0.1⁠

⁠Quick Start for SPAs *

⁠Modern Single Page Applications

If you are building modern frontend applications (e.g. Vue⁠, React⁠, Angular⁠) you would most probably be compiling a modern version of JavaScript (ES2015, TypeScript, etc) to a less modern, more compatible version.

If you want to serve your (compiled) frontend code by the same backend (Flask) Docker container, you would have to copy the code to the container after compiling it.

That means that you would need to have all the frontend tools installed on the building machine (it might be your computer, a remote server, etc).

That also means that you would have to, somehow, always remember to compile the frontend code right before building the Docker image.

And it might also mean that you could then have to add your compiled frontend code to your git repository (hopefully you are using Git already, or learning how to use git⁠).

Adding your compiled code to Git is a very bad idea for several reasons, some of those are:

  • You don't have a single, ultimate source of truth (the source code).
  • The compiled code might be stale, even when your source code is new, which might make you spend a lot of time debugging.
  • You might run into a lot of code conflicts when interacting with multiple team members with different Git branches, and spend a lot of time solving irrelevant code conflicts in the compiled code.
    • This might also ruin automatic branch merging in pull requests from other team members.

For these reasons, it is not recommended that you serve your frontend code from the same backend (Flask) Docker container.

⁠Better alternative

There's a much better alternative to serving your frontend code from the same backend (Flask) Docker container.

You can have another Docker container with all the frontend tools installed (Node.js, etc) that:

  • Takes your source frontend code.
  • Compiles it and generates the final "distributable" frontend.
  • Uses Docker "multi-stage builds" to copy that compiled code into a pure Nginx Docker image.
  • The final frontend image only contains the compiled frontend code, directly from the source, but has the small size of an Nginx image, with all the performance from Nginx.

To learn the specifics of this process for the frontend building in Docker you can read:

After having one backend (Flask) container and one frontend container, you need to serve both of them.

And you might want to serve them under the same domain, under a different path. For example, the backend (Flask) app at the path /api and the frontend at the "root" path /.

You can then use Traefik⁠ to handle that.

And it can also automatically generate HTTPS certificates for your application using Let's Encrypt. All for free, in a very easy setup.

In this scenario, you would have 3 Docker containers:

  • Backend (Flask)
  • Frontend (Vue.js, Angular, React or any other)
  • Traefik (load balancer, HTTPS)

⁠Quick Start for bigger projects structured as a Python package

You should be able to follow the same instructions as in the "QuickStart" section above, with some minor modifications:

  • Instead of putting your code in the app/ directory, put it in a directory app/app/.
  • Add an empty file __init__.py inside of that app/app/ directory.
  • Add a file uwsgi.ini inside your app/ directory (that is copied to /app/uwsgi.ini inside the container).
  • In your uwsgi.ini file, add:
[uwsgi]
module = app.main
callable = app

The explanation of the uwsgi.ini is as follows:

  • The module in where my Python web app lives is app.main. So, in the package app (/app/app), get the main module (main.py).
  • The Flask web application is the app object (app = Flask(__name__)).

Your file structure would look like:

.
├── app
│   ├── app
│   │   ├── __init__.py
│   │   ├── main.py
│   └── uwsgi.ini
└── Dockerfile

...instead of:

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

If you are using static files in the same container, make sure the STATIC_PATH environment variable is set accordingly, for example to change the default value of /app/static to /app/app/static you could add this line to your Dockerfile:

ENV STATIC_PATH /app/app/static

...after that, everything should work as expected. All the other instructions would apply normally.

⁠Working with submodules
  • After adding all your modules you could end up with a file structure similar to (taken from the example project):
.
├── app
│   ├── app
│   │   ├── api
│   │   │   ├── api.py
│   │   │   ├── endpoints
│   │   │   │   ├── __init__.py
│   │   │   │   └── user.py
│   │   │   ├── __init__.py
│   │   │   └── utils.py
│   │   ├── core
│   │   │   ├── app_setup.py
│   │   │   ├── database.py
│   │   │   └── __init__.py
│   │   ├── __init__.py
│   │   ├── main.py
│   │   └── models
│   │       ├── __init__.py
│   │       └── user.py
│   └── uwsgi.ini
└── Dockerfile

from .core import app_setup

or

from app.core import app_setup
  • And if you are in app/app/api/endpoints/user.py and you want to import the users object from app/app/core/database.py you would write it like:
from ...core.database import users

or

from app.core.database import users

⁠Advanced instructions

You can customize several things using environment variables.

⁠Serve index.html directly

Notice: this technique is deprecated, as it can create several issues with modern frontend frameworks. For the details and better alternatives, read the section above.

Setting the environment variable STATIC_INDEX to be 1 you can configure Nginx to serve the file in the URL /static/index.html when requested for /.

That would improve speed as it would not involve uWSGI nor Python. Nginx would serve the file directly. To learn more follow the section above "QuickStart for SPAs".

For example, to enable it, you could add this to your Dockerfile:

ENV STATIC_INDEX 1
⁠Custom uWSGI process number

By default, the image starts with 2 uWSGI processes running. When the server is experiencing a high load, it creates up to 16 uWSGI processes to handle it on demand.

If you need to configure these numbers you can use environment variables.

The starting number of uWSGI processes is controlled by the variable UWSGI_CHEAPER, by default set to 2.

The maximum number of uWSGI processes is controlled by the variable UWSGI_PROCESSES, by default set to 16.

Have in mind that UWSGI_CHEAPER must be lower than UWSGI_PROCESSES.

So, if, for example, you need to start with 4 processes and grow to a maximum of 64, your Dockerfile could look like:

FROM tiangolo/uwsgi-nginx-flask:python3.12
ENV UWSGI_CHEAPER 4
ENV UWSGI_PROCESSES 64
COPY ./app /app
⁠Max upload file size

You can set a custom maximum upload file size using an environment variable NGINX_MAX_UPLOAD, by default it has a value of 0, that allows unlimited upload file sizes. This differs from Nginx's default value of 1 MB. It's configured this way because that's the simplest experience an inexperienced developer in Nginx would expect.

For example, to have a maximum upload file size of 1 MB (Nginx's default) add a line in your Dockerfile with:

ENV NGINX_MAX_UPLOAD 1m
⁠Custom listen port

By default, the container made from this image will listen on port 80.

To change this behavior, set the LISTEN_PORT environment variable. You might also need to create the respective EXPOSE Docker instruction.

You can do that in your Dockerfile, it would look something like:

FROM tiangolo/uwsgi-nginx-flask:python3.12
ENV LISTEN_PORT 8080
EXPOSE 8080
COPY ./app /app
⁠Custom uwsgi.ini configurations

There is a default file in /app/uwsgi.ini with app specific configurations (on top of the global uwsgi configurations).

It only contains:

[uwsgi]
module = main
callable = app
  • module = main refers to the file main.py.
  • callable = app refers to the Flask "application", in the variable app.

You can customize uwsgi by replacing that file with your own, including all your configurations.

For example, to extend the default one above and enable threads, you could have a file:

[uwsgi]
module = main
callable = app
enable-threads = true
⁠Custom uwsgi.ini file location

You can override where the image should look for the app uwsgi.ini file using the environment variable UWSGI_INI.

With that you could change the default directory for your app from /app to something else, like /application.

For example, to make the image use the file in /application/uwsgi.ini, you could add this to your Dockerfile:

ENV UWSGI_INI /application/uwsgi.ini
COPY ./application /application
WORKDIR /application

Note: the WORKDIR is important, otherwise uWSGI will try to run the app in /app.

Note: you would also have to configure the static files path, read below.

⁠Custom ./static/ path

You can make Nginx use a custom directory path with the files to serve directly (without having uWSGI involved) with the environment variable STATIC_PATH.

For example, to make Nginx serve the static content using the files in /app/custom_static/ you could add this to your Dockerfile:

ENV STATIC_PATH /app/custom_static

Then, when the browser asked for a file in, for example, http://example.com/static/index.html⁠, Nginx would answer directly using a file in the path /app/custom_static/index.html.

Note: you would also have to configure Flask to use that as its static directory.

As another example, if you needed to put your application code in a different directory, you could configure Nginx to serve those static files from that different directory.

If you needed to have your static files in /application/static/ you could add this to your Dockerfile:

ENV STATIC_PATH /application/static
⁠Custom /static URL

You can also make Nginx serve the static files in a different URL, for that, you can use the environment variable STATIC_URL.

For example, if you wanted to change the URL /static to /content you could add this to your Dockerfile:

ENV STATIC_URL /content

Then, when the browser asked for a file in, for example, http://example.com/content/index.html⁠, Nginx would answer directly using a file in the path /app/static/index.html.

⁠Custom /app/prestart.sh

If you need to run anything before starting the app, you can add a file prestart.sh to the directory /app. The image will automatically detect and run it before starting everything.

For example, if you want to add Alembic SQL migrations (with SQLAlchemy), you could create a ./app/prestart.sh file in your code directory (that will be copied by your Dockerfile) with:

#! /usr/bin/env bash
# Let the DB start
sleep 10;
# Run migrations
alembic upgrade head

and it would wait 10 seconds to give the database some time to start and then run that alembic command.

If you need to run a Python script before starting the app, you could make the /app/prestart.sh file run your Python script, with something like:

#! /usr/bin/env bash
# Run custom Python script before starting
python /app/my_custom_prestart_script.py

Note: The image uses source to run the script, so for example, environment variables would persist. If you don't understand the previous sentence, you probably don't need it.

⁠Custom Nginx processes number

By default, Nginx will start one "worker process".

If you want to set a different number of Nginx worker processes you can use the environment variable NGINX_WORKER_PROCESSES.

You can use a specific single number, e.g.:

ENV NGINX_WORKER_PROCESSES 2

or you can set it to the keyword auto and it will try to auto-detect the number of CPUs available and use that for the number of workers.

For example, using auto, your Dockerfile could look like:

FROM tiangolo/uwsgi-nginx-flask:python3.12
ENV NGINX_WORKER_PROCESSES auto
COPY ./app /app
⁠Custom Nginx maximum connections per worker

By default, Nginx will start with a maximum limit of 1024 connections per worker.

If you want to set a different number you can use the environment variable NGINX_WORKER_CONNECTIONS, e.g:

ENV NGINX_WORKER_CONNECTIONS 2048

It cannot exceed the current limit on the maximum number of open files. See how to configure it in the next section.

⁠Custom Nginx maximum open files

The number connections per Nginx worker cannot exceed the limit on the maximum number of open files.

You can change the limit of open files with the environment variable NGINX_WORKER_OPEN_FILES, e.g.:

ENV NGINX_WORKER_OPEN_FILES 2048
⁠Customizing Nginx additional configurations

If you need to configure Nginx further, you can add *.conf files to /etc/nginx/conf.d/ in your Dockerfile.

Just have in mind that the default configurations are created during startup in a file at /etc/nginx/conf.d/nginx.conf and /etc/nginx/conf.d/upload.conf. So you shouldn't overwrite them. You should name your *.conf file with something different than nginx.conf or upload.conf, for example: custom.conf.

Note: if you are customizing Nginx, maybe copying configurations from a blog or a StackOverflow answer, have in mind that you probably need to use the configurations specific to uWSGI⁠, instead of those for other modules, like for example, ngx_http_fastcgi_module.

⁠Overriding Nginx configuration completely

If you need to configure Nginx even further, completely overriding the defaults, you can add a custom Nginx configuration to /app/nginx.conf.

It will be copied to /etc/nginx/nginx.conf and used instead of the generated one.

Have in mind that, in that case, this image won't generate any of the Nginx configurations, it will only copy and use your configuration file.

That means that all the environment variables described above that are specific to Nginx won't be used.

It also means that it won't use additional configurations from files in /etc/nginx/conf.d/*.conf, unless you explicitly have a section in your custom file /app/nginx.conf with:

include /etc/nginx/conf.d/*.conf;

If you want to add a custom /app/nginx.conf file but don't know where to start from, you can use the nginx.conf used for the tests⁠ and customize it or modify it further.

⁠Technical details

The combination of uWSGI with Nginx is a common way to deploy Python Flask web applications⁠.

Roughly:

  • Nginx is a web server, it takes care of the HTTP connections and also can serve static files directly and more efficiently.

  • uWSGI is an application server, that's what runs your Python code and it talks with Nginx.

  • Your Python code has the actual Flask web application, and is run by uWSGI.

The image tiangolo/uwsgi-nginx⁠ takes advantage of already existing slim and optimized Docker images (based on Debian as recommended by Docker⁠) and implements several of Docker's best practices.

It uses the official Python Docker image, installs uWSGI and on top of that (with the least amount of modifications) adds the official Nginx image.

And it controls all these processes with Supervisord.

The image (and tags) created by this repo is based on the image tiangolo/uwsgi-nginx⁠. This image adds Flask and sensible defaults on top of it.

If you follow the instructions and keep the root directory /app in your container, with a file named main.py and a Flask object named app in it, it should "just work".

There's already a uwsgi.ini file in the /app directory with the uWSGI configurations for it to "just work". And all the other required parameters are in another uwsgi.ini file in the image, inside /etc/uwsgi/.

If you need to change the main file name or the main Flask object, you would have to provide your own uwsgi.ini file. You may use the one in this repo as a template to start with (and you only would have to change the 2 corresponding lines).

You can ha

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