wheezy web: deploy nginx + uwsgi + memcached

wheezy.web is a lightweight, high performance, high concurrency WSGI web framework with the key features to build modern, efficient web. Here we will deploy quick start with nginx, uwsgi and memcached to clean debian stable installation.

How to rewrite all to https in nginx

Here we are going redirect all http traffic to https with nginx. I suppose you already have nginx installed, if not have a look here. We will store SSL certificates in /etc/nginx/ssl directory.

cd /etc/nginx
mkdir ssl
openssl req -new -x509 -sha256 -days 9999 -nodes \
    -out ssl/cert.pem -keyout ssl/cert.key
chown -R www-data:www-data ssl
chmod -R 700 ssl

Here is nginx configuration:

upstream backend {
    server 127.0.0.1:8080;
}

server {
    listen  *:80;
    return 301 https://$host$request_uri;
    #if ( $scheme = "http" ) {
    #    rewrite  ^/(.*)$  https://$host/$1 permanent;
    #}
}

server {
    listen  *:443;

    ssl on;
    ssl_protocols TLSv1;
    ssl_certificate /etc/nginx/ssl/cert.pem;
    ssl_certificate_key /etc/nginx/ssl/cert.key;

    location / {
        proxy_pass http://backend;
    }
}

You have to reload nginx so the changes take place.

How to Install django on Debian using nginx uwsgi

Here we are going install a basic django application using uwsgi application server and nginx as load balancer. Requirements:

• django code location: /usr/local/lib
• django project: hello

Let install few packages we need:

apt-get -y install nginx uwsgi \
    uwsgi-plugin-python python-django

Create a simple django application:

cd /usr/local/lib
django-admin startproject hello

uWSGI

Create uWSGI configuration (file /etc/uwsgi/apps-available/hello.yaml):

uwsgi:
    uid: www-data
    gid: www-data
    socket: /tmp/uwsgi-hello.sock
    plugins: http, python
    module: django.core.handlers.wsgi:WSGIHandler()
    pythonpath: /usr/local/lib
    chdir: /usr/local/lib/hello
    env: DJANGO_SETTINGS_MODULE=hello.settings 

Enable this configuration and restart uwsgi server:

ln -s /etc/uwsgi/apps-available/hello.yaml \
    /etc/uwsgi/apps-enabled/hello.yaml
/etc/init.d/uwsgi restart

nginx

Create nginx site configuration (file /etc/nginx/sites-available/hello):

upstream backend {
    server unix:///tmp/uwsgi-hello.sock;
}

server {
    location / { 
        uwsgi_pass  backend;
        include     uwsgi_params;
    }   

    location /static/admin/ {
        alias /usr/lib/pymodules/python2.6/django/contrib/admin/media/;
        access_log off;
        expires 7d;
    }

    location  /static/ {
        alias  /usr/local/lib/hello/static/;
        access_log off;
        expires 7d;
    }
}

Remove default site, enable this configuration and restart nginx server:

rm /etc/nginx/sites-enabled/default
ln -s /etc/nginx/sites-available/hello \
    /etc/nginx/sites-enabled/hello
/etc/init.d/nginx restart

nginx - uwsgi_cache

Web sites that serve almost static content (updated let say every 15 mins) can benefit by utilizing content caching:

   ...
uwsgi_cache_path   /var/cache/hello levels=1:2
                   keys_zone=NAME:15m
                   inactive=5m;
server {
   location / {
       uwsgi_pass  backend;
       include     uwsgi_params;
       uwsgi_cache   NAME;
       uwsgi_cache_valid   200 302 15m;
       uwsgi_cache_key $request_uri;
       expires 15m;
   }
   ...
}

If you experience performance issue with content rendering, overhead of framework internal time, have a willing to fine control content caching consider take a look at the following post and this one.

Simple Load Balancing with nginx on Debian

Suppose you need distribute http workload across multiple computers/processes. Here we will be using nginx to implement load balancing (using round-robin scheduling). Let start by installing nginx package:

apt-get -y install nginx

Place the following into /etc/nginx/sites-available/my-site:

upstream backend {
    // every 7 requests: 5 requests to s1 server 
    // and one request to the second and the third
    server s1 weight=5;
    // after 3 unsuccessful attempts within 
    // the 30 seconds s2 is considered 
    // inoperative
    server unix:/tmp/s2 max_fails=3 fail_timeout=30s;
    server 127.0.0.1:8080;
}   
 
server {
    location / {
       proxy_pass http://backend;
    }   
}  

Now disable default site configuration, enable a new one and restart nginx:

rm /etc/nginx/sites-enabled/default
ln -s /etc/nginx/sites-available/my-site \
    /etc/nginx/sites-enabled/my-site
/etc/init.d/nginx restart

Read more about nginx upstream module here.