Setting up Nginx, uWSGI & Python3

nginx-uwsgi-python3

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Setting up Nginx, uWSGI and Python3
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First off, I'm traditionally a PHP developer, but am looking at moving across to Python. I really struggled to find decent documentation on how to get a server up and running for deploying Python web applications from the point of view of someone coming from PHP. The main problems I came across with documentation were:

1) Only showed you how to run the server for a single web application.
2) Only showed you how to configure the app, not the server it was running on.

My preferred workflow for development is by setting up a new VM in VMware Fusion and then forwarding through all requests to that VM via /etc/hosts. This might not be the optimal way to get things up and running, but it works for me.

SITE_URL refers to the primary domain for the site.
SITE_DIR refers to the location on disk that the site is located.

Typical folder structure of an app looks something like:

root
    app # site code goes in here
    config
    data
        cache
        log
    libs
        vendors # frameworks and 3rd party libraries go in here
    public
        css
        img
        js

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Installing required tools
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We'll start by installing the required tools via apt-get.

apt-get install uwsgi uwsgi-plugin-python3 nginx-full python-setuptools python-pip

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Creating the uWSGI upstart
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Next we need to create the upstart that will be used start the uWSGI service.

vi /etc/init/uwsgi.conf

    # uWSGI - Manage uWSGI Application Server
    description "uWSGI Emperor Mode"
    start on (filesystem and net-device-up IFACE=lo)
    stop on runlevel [!2345]
    respawn
    exec /usr/bin/uwsgi --emperor /etc/uwsgi/vassals/sites-enabled/ --logto /var/log/uwsgi.log

initctl reload-configuration
update-alternatives --set uwsgi /usr/bin/uwsgi_python32

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Creating the site configuration file for nginx
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Create the configuration file for the site in the sites-available folder:
    vi /etc/nginx/sites-available/SITE_URL

And then use the following to configure the site:
    upstream wsgicluster {
        server unix://tmp/SITE_URL.sock
    }
    server {
        listen 80;
        server_name SITE_URL;
        error_log SITE_DIR/data/log/error.log;
        access_log SITE_DIR/data/log/access.log;
        location / {
                include uwsgi_params;
                uwsgi_pass wsgicluster;
        }
        location -^/(img|js|css)/ {
                root SITE_DIR/public;
                expires 30d;
        }
        location = /favicon.ico {
                log_not_found off;
        }
    }

Then finally we link the sites-available configuration file to the sites-enabled:
ln -s /etc/nginx/sites-available/SITE_URL /etc/nginx/sites-enabled/SITE_URL

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Creating the vassal for uWSGI emperor
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Create the folders for sites-available and sites-enabled:
    mkdir /etc/uwsgi/sites-available
    mkdir /etc/uwsgi/sites-enabled

Create the configuration vassal file:
    vi /etc/uwsgi/sites-available/SITE_URL.yml

And then use the following contents (you can tweak these settings):
    uwsgi:
        master: true
        processes: 1
        vaccum: true
        chmod-socket: 666
        uid: www-data
        gid: www-data
        plugins: python32
        socket: /tmp/SITE_URL.sock
        chdir: SITE_DIR
        pythonpath: SITE_DIR
        module: application
        touch-reload: SITE_DIR/application.py

Finally restart the services:
    service uwsgi start
    service nginx start

I have my automation tool in python2.7 now. It is deployed with django1.11+nginx+wsgi. When I tried migrating to python3, it fails. I installed everything w.r.t. python3, created a new virtualenv, but I get "Internal Server Error".