Getting a Flask website up and running in Ubuntu

This is a guide to get a Flask website up and running on Ubuntu 12.04 LTS using nginx and uWSGI. There are many routes to take when it comes to Python on the web; this just is my personal favorite. Some people enjoy configuring servers, while others view it as a chore. Regardless, this guide should get you up, running, and ready to make something awesome in no time!

Installation

nginx

To install nginx you first need to add the repository. Add the following to /etc/apt/sources.list.d/nginx-lucid.list :

You will also want to add the gpg key to the apt keyring:

Finally, to install nginx, run:

uWSGI

You can use pip to install the latest version of uWSGI by doing the following:

To configure uWSGI to run as a daemon, you first want to create a separate uwsgi user:

You then want to create an upstart configuration file, to run uWSGI in the background. Add the following to /etc/init/uwsgi.conf :

To set up logging, you can add a logrotate configuration file at /etc/logrotate.d/uwsgi:

and to prime the log file, you can run:

It is okay if there is an error with the postrotate script. uWSGI cannot be restarted because it is not currently running.

virtualenv

Using virtualenv is a good idea because it compartmentalizes the environment of your application. To install virtualenv, you can use pip:

Configuration

Flask

Now to set up the website! In this case, the website is going to be called 'helloworld' and it is going to be set up in /srv/www/helloworld. Feel free to change it, just adjust these instructions accordingly.

The first step is to create the directory:

and a subdirectory for static files, to be hosted by nginx:

The next step is to create a virtual environment for the application to run in:

and to install Flask in that environment:

Now that that is done, let's create a sample 'Hello World' application, in application.py:

The permissions of the directory now have to be configured. uWSGI needs read permission to read the contents of the scripts, and write permission to save compiled python files:

Nginx

The final step is to configure nginx. First, remove the default configuration file:

Now, add the helloworld configuration file at /etc/nginx/conf.d/helloworld.conf:

Running it

Now that you have successfully configured your website, you can run it using:

Extensions

Flask

Flask is fantastic because it is very extensible. Check out the documentation to get started.

More Websites!

It is really easy to add more websites to this configuration. Simply create a new application directory, set it up, and create a second nginx configuration. uWSGI is configured to be in virtualhost mode, so it can handle multiple websites at once.

Portability

You can also use uWSGI as an http server, for testing purposes. If you have a copy of your website checked out in the current directory, you can run

and uWSGI will create a HTTP server hosting your application on port 9090. This is incredibly useful for development.

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