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Docker image with uWSGI and Nginx for applications in Python 3.7, 3.6, 3.5 and Python 2.7 (as Flask) in a single container. Optionally with Alpine Linux.
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uwsgi-nginx

Docker image with uWSGI and Nginx for web applications in Python 3.7, Python 3.6, Python 3.5 and Python 2.7 (as Flask) in a single container. Optionally with Alpine Linux.

Description

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

The combination of uWSGI with Nginx is a common way to deploy Python web applications like Flask and Django. It is widely used in the industry and would give you decent performance. (*)

There is also an Alpine version. If you want it, use one of the Alpine tags from above.

This image was created to be the base image for tiangolo/uwsgi-nginx-flask but could be used as the base image for any other (WSGI-based) Python web application, like Django.

* Note on performance and features

If you are starting a new project, you might benefit from a newer and faster framework based on ASGI instead of WSGI (Flask and Django are WSGI-based).

You could use an ASGI framework like:

FastAPI, or Starlette, would give you about 800% (8x) the performance achievable with this image (tiangolo/uwsgi-nginx). You can see the third-party benchmarks here.

Also, if you want to use new technologies like WebSockets it would be easier (and possible) with a newer framework based on ASGI, like FastAPI or Starlette. As the standard ASGI was designed to be able to handle asynchronous code like the one needed for WebSockets.

If you need a WSGI-based application (like Flask or Django)

If you need to use an older WSGI-based framework like Flask or Django (instead of something based on ASGI) and you need to have the best performance possible, you can use the alternative image: tiangolo/meinheld-gunicorn.

tiangolo/meinheld-gunicorn will give you about 400% (4x) the performance of this image.


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

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

How to use

  • You shouldn't have to clone the GitHub repo. You should use it as a base image for other images, using this in your Dockerfile:
FROM tiangolo/uwsgi-nginx:python3.7

# Your Dockerfile code...
  • But, if you need Python 2.7 that line would have to be FROM tiangolo/uwsgi-nginx:python2.7.

  • By default it will try to find a uWSGI config file in /app/uwsgi.ini.

  • That uwsgi.ini file will make it try to run a Python file in /app/main.py.

If you are building a Flask web application you should use instead tiangolo/uwsgi-nginx-flask.

Advanced usage

Custom app directory

If you need to use a directory for your app different than /app, you can override the uWSGI config file path with an environment variable UWSGI_INI, and put your custom uwsgi.ini file there.

For example, if you needed to have your application directory in /application instead of /app, your Dockerfile would look like:

FROM tiangolo/uwsgi-nginx:python3.7

ENV UWSGI_INI /application/uwsgi.ini

COPY ./application /application
WORKDIR /appapplication

And your uwsgi.ini file in ./application/uwsgi.ini would contain:

[uwsgi]
wsgi-file=/application/main.py

Note: it's important to include the WORKDIR option, otherwise uWSGI will start the application in /app.

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:python3.7

ENV UWSGI_CHEAPER 4
ENV UWSGI_PROCESSES 64

COPY ./app /app

Custom max upload size

In this image, Nginx is configured to allow unlimited upload file sizes. This is done because by default a simple Python server would allow that, so that's the simplest behavior a developer would expect.

If you need to restrict the maximum upload size in Nginx, you can add an environment variable NGINX_MAX_UPLOAD and assign a value corresponding to the standard Nginx config client_max_body_size.

For example, if you wanted to set the maximum upload file size to 1 MB (the default in a normal Nginx installation), you would need to set the NGINX_MAX_UPLOAD environment variable to the value 1m. Then the image would take care of adding the corresponding configuration file (this is done by the entrypoint.sh).

So, your Dockerfile would look something like:

FROM tiangolo/uwsgi-nginx:python3.7

ENV NGINX_MAX_UPLOAD 1m

COPY ./app /app

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:python3.7

ENV LISTEN_PORT 8080

EXPOSE 8080

COPY ./app /app

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 autodetect 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:python3.7

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.

What's new

  • 2019-02-02:

    • The Nginx configurations are generated dynamically from the entrypoint, instead of modifying pre-existing files. PR #50.
    • Support for a completely custom /app/nginx.conf file that overrides the generated one. PR #51.
  • 2018-11-23: New Alpine 3.8 images for Python 2.7, Python 3.6 and Python 3.7 (Python 3.7 temporarily disabled). Thanks to philippfreyer in PR #45

  • 2018-09-22: New Python 3.7 versions, standard and Alpine based. Thanks to desaintmartin in this PR.

  • 2018-06-22: You can now use NGINX_WORKER_CONNECTIONS to set the maximum number of Nginx worker connections and NGINX_WORKER_OPEN_FILES to set the maximum number of open files. Thanks to ronlut in this PR.

  • 2018-06-22: Make uWSGI require an app to run, instead of going in "full dynamic mode" while there was an error. Supervisord doesn't terminate itself but tries to restart uWSGI and shows the errors. Uses need-app as suggested by luckydonald in this comment.

  • 2018-06-22: Correctly handled graceful shutdown of uWSGI and Nginx. Thanks to desaintmartin in this PR.

  • 2018-02-04: It's now possible to set the number of Nginx worker processes with the environment variable NGINX_WORKER_PROCESSES. Thanks to naktinis in this PR.

  • 2018-01-14: There are now two Alpine based versions, python2.7-alpine3.7 and python3.6-alpine3.7.

  • 2017-12-08: Now you can configure which port the container should listen on, using the environment variable LISTEN_PORT thanks to tmshn in this PR.

  • 2017-08-09: 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 a developer that is not expert in Nginx would expect.

  • 2017-08-09: Now you can override where to look for the uwsgi.ini file, and with that, change the default directory from /app to something else, using the envirnoment variable UWSGI_INI.

  • 2017-08-08: There's a new latest tag image, just to show a warning for those still using latest for Python 2.7 web applications. As of now, everyone should be using Python 3.

  • 2017-08-08: Supervisord now terminates uWSGI on SIGTERM, so if you run docker stop or something similar, it will actually stop everything, instead of waiting for Docker's timeout to kill the container.

  • 2017-07-31: There's now an image tag for Python 3.6, based on the official image for Python 3.6 thanks to jrd in this PR.

  • 2016-10-01: Now you can override default uwsgi.ini parameters from the file in /app/uwsgi.ini.

  • 2016-08-16: There's now an image tag for Python 3.5, based on the official image for Python 3.5. So now you can use this image for your projects in Python 2.7 and Python 3.5.

  • 2016-08-16: Use dynamic a number of worker processes for uWSGI, from 2 to 16 depending on load. This should work for most cases. This helps especially when there are some responses that are slow and take some time to be generated, this change allows all the other responses to keep fast (in a new process) without having to wait for the first (slow) one to finish.

  • Also, it now uses a base uwsgi.ini file under /etc/uwsgi/ with most of the general configurations, so, the uwsgi.ini inside /app (the one you could need to modify) is now a lot simpler.

  • 2016-04-05: Nginx and uWSGI logs are now redirected to stdout, allowing to use docker logs.

Technical details

The combination of uWSGI with Nginx is a common way to deploy Python 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 web application, and is run by uWSGI.

This image takes advantage of already slim and optimized existing Docker images (based on Debian as recommended by Docker) and implements Docker 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 (as of 2016-02-14).

And it controls all these processes with Supervisord.


There's the rule of thumb that you should have "one process per container".

That helps, for example, isolating an app and its database in different containers.

But if you want to have a "micro-services" approach you may want to have more than one process in one container if they are all related to the same "service", and you may want to include your Flask code, uWSGI and Nginx in the same container (and maybe run another container with your database).

That's the approach taken in this image.


This image has a default sample "Hello World" app in the container's /app directory using the example in the uWSGI documentation.

You probably want to override it or delete it in your project.

It is there in case you run this image by itself and not as a base image for your own Dockerfile, so that you get a sample app without errors.

Tests

All the image tags, configurations, environment variables and application options are tested.

License

This project is licensed under the terms of the Apache license.

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