web applications | Eclectic Security

Lately I’ve been working on developing a web application project, I guess everyone involved in such process had to make the uneasy decision to choose the right Web Stack to run the application. Multiple factors usually drive the final decision,total cost of ownership (TCO), scalability, stability and performances. The TCO factor can be easy overcome with FLOSS (Free and open source software), scalability is a very broad term and concept that doesn’t have any clear answer. Stability can be achieved with software that is widely used and widely reviewed and tested for a long time, never pick something new just because it’s cool. Doesn’t matter if the website serve millions of users or just a few hundred, slow or bad performances can make the user experience a nightmare. Performance enhancement can be achieved with, Memory caching system, Low memory footprint web servers, good and slim database design, query optimization to work under heavy loads. Please be aware that applications, services and workloads differ from case to case, you might need more write capacity rather than read, serving multimedia files or whatever else, don’t blame me if you have troubles with your production application after following this how-to. For me and some other, this setup works quite well, I hope the same for you .

This tutorial covers the set up a free, full-featured web development framework based on Ubuntu Server 12.04(LTS), Django 1.4 stable, Postgresql database V. 9.1, Nginx web server V.1.1.19 and Gunicorn.

Ubuntu Server
Linux for high-volume server workloads
http://www.ubuntu.com/business/server/overview

Django
The web framework for perfectionists with deadlines
www.djangoproject.com

Postgresql
A powerful, open source object-relational database system.
http://www.postgresql.org

Nginx
A web server with a strong focus on high concurrency, performance and low memory usage.
http://wiki.nginx.org/Main

Gunicorg
A WSGI HTTP Server, the link between Django an Nginx.
http://gunicorn.org/

Postgresql installation and setup


apt-get install postgresql python-psycopg2

sudo -u postgres psql template1

ALTER USER postgres with encrypted password 'a_strong_password';

template1=# CREATE DATABASE test;

template1=# CREATE USER test WITH PASSWORD 'test';

template1=# GRANT ALL PRIVILEGES ON DATABASE test to test;

In /etc/postgresql/9.1/main/pg_hba.conf

Change

local   all             postgres                                peer

To

local   all             postgres                                md5

local   all             all                                     peer

to

local   all             all                                     md5

Restart Postgresql server with:

/etc/init.d/postgresql restart

To thest the local connection to the database please use:

psql -d postgres -U postgres

and

psql -d test -U test

Django installation and setup.

apt-get install aria2c

aria2c http://www.djangoproject.com/download/1.4/tarball/

tar xvfz Django-1.4.tar.gz

python setup.py install

mkdir /var/djangoweb/

django-admin.py  startproject myproject

django-admin.py  startproject myproject

cd myproject/

mkdir /var/djangoweb/myproject/static

ln -s /usr/local/lib/python2.7/dist-packages/django/contrib/admin /var/djangoweb/myproject/static/

in myproject/settings.py

Add

import os.path
PROJECT_DIR = os.path.dirname(__file__)

Database setup in django

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2', # Add 'postgresql_psycopg2', 'mysql', 'sqlite3' or 'oracle'.
        'NAME': 'test',                      # Or path to database file if using sqlite3.
        'USER': 'test',                      # Not used with sqlite3.
        'PASSWORD': 'test',                  # Not used with sqlite3.
        'HOST': '',                      # Set to empty string for localhost. Not used with sqlite3.
        'PORT': '',                      # Set to empty string for default. Not used with sqlite3.
    }
}

Then go to the INSTALLED_APPS section and uncomment
django.contrib.admin line.

INSTALLED_APPS = (
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.sites',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    # Uncomment the next line to enable the admin:
    # 'django.contrib.admin',
    # Uncomment the next line to enable admin documentation:
    # 'django.contrib.admindocs',
)

and # ‘django.contrib.admin’,

INSTALLED_APPS = (
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.sites',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    # Uncomment the next line to enable the admin:
    'django.contrib.admin',
    # Uncomment the next line to enable admin documentation:
    # 'django.contrib.admindocs',
)

in myproject/urls.py uncomment the following lines.


from django.contrib import admin
admin.autodiscover()

url(r'^admin/', include(admin.site.urls)),

The urls.py file have to look like this.

from django.conf.urls import patterns, include, url

# Uncomment the next two lines to enable the admin:
from django.contrib import admin
admin.autodiscover()

urlpatterns = patterns('',
    # Examples:
    # url(r'^$', 'myproject.views.home', name='home'),
    #url(r'^myproject/', include('myproject.foo.urls')),

    # Uncomment the admin/doc line below to enable admin documentation:
    # url(r'^admin/doc/', include('django.contrib.admindocs.urls')),

    # Uncomment the next line to enable the admin:
    url(r'^admin/', include(admin.site.urls)),
)

Now the basic parameters are defined, we must perform the first database synchronization,
go on top of the project root and issue the “python manage.py syncdb” command.

You’ll see the creation of the first Django tables inside the database, you also need to create
the administrator user.

Creating tables ...
Creating table auth_permission
Creating table auth_group_permissions
Creating table auth_group
Creating table auth_user_user_permissions
Creating table auth_user_groups
Creating table auth_user
Creating table django_content_type
Creating table django_session
Creating table django_site
Creating table django_admin_log

You just installed Django's auth system, which means you don't have any superusers defined.
Would you like to create one now? (yes/no): yes
Username (leave blank to use 'root'): phillip
E-mail address: phillip@foo.com
Password:
Password (again):
Superuser created successfully.
Installing custom SQL ...
Installing indexes ...
Installed 0 object(s) from 0 fixture(s)

At this point the Django interaction with the database looks working properly.

In order to get access to Django administration page you need to run the
embedded python web server.


python manage.py runserver 0.0.0.0:80
Validating models...

0 errors found
Django version 1.4, using settings 'myproject.settings'
Development server is running at http://0.0.0.0:80/
Quit the server with CONTROL-C.

Point the browser to:

http://server_ipaddress/admin/

Gunicorn installation and setup

Install gunicorn


apt-get install git python-setuptools
git clone git://github.com/benoitc/gunicorn.git
cd gunicorn/
python setup.py install

inside the root project folder myproject

vim gunicorn.conf.py

bind = "127.0.0.1:8888"
workers = 2
#recommended (2 x $num_cores) + 1

To run gunicor go in the root project folder and run:

gunicorn_django -c gunicorn.conf.py

To Daemonize the Gunicorn process add -D

gunicorn_django -c gunicorn.conf.py -D

Yum must get:

gunicorn_django -c gunicorn.conf.py
2012-05-01 19:53:28 [6176] [INFO] Starting gunicorn 0.14.2
2012-05-01 19:53:28 [6176] [INFO] Listening at: http://127.0.0.1:8888 (6176)
2012-05-01 19:53:28 [6176] [INFO] Using worker: sync
2012-05-01 19:53:28 [6180] [INFO] Booting worker with pid: 6180
2012-05-01 19:53:28 [6181] [INFO] Booting worker with pid: 6181

Nginx installation and configuration


apt-get install nginx-full  openssl

rm /etc/nginx/sites-enabled/default

touch /etc/nginx/sites-available/django

ln -s /etc/nginx/sites-available/django  /etc/nginx/sites-enabled/django

In /etc/nginx/sites-enabled/django please add:


server {

listen   server_ipaddress:80;
#server_name *.site1;

access_log /var/log/nginx/djangosite1.access.log;
error_log /var/log/nginx/djangosite1.error.log;

location / {
        proxy_pass http://127.0.0.1:8888;

}

#location /static {
#         autoindex on;
#         root /root/blog/public_html/;
#    }

location /static/admin {
         autoindex on;
         root /var/djangoweb/myproject/static/admin;
    }

}

/etc/init.d/nginx restart

Django admin web interface.

Now you can point the browser to http://server_ipaddress/admin/, be aware the myproject directory is just the schema container for the project, no applications are yet configured or installed. I strongly advise to follow “Writing your first Django app” how-to, do not copy paste the code.

If you want to find more about django development please take a look to:

Django From the Ground Up video series
DjangoCon 2011
The Django book

I hope this document will be useful for who is struggling with Django setup. Stay tuned.

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Tag Archives: web applications

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