Presentation given at #djangocong

1. WSGI, Django &
Gunicorn
Benoît Chesneau
25/04/2010 - djangocong
Sunday, April 25, 2010

2. benoît chesneau
benoitc@apache.org
Artisan web
Minimal web & Opensource
Enki Multimedia
http://www.e-engura.com
Sunday, April 25, 2010

3. • WSGI ?
• Django & WSGI
• Gunicorn
Sunday, April 25, 2010

4. WSGI ?
• Web Server Gateway Interface
• PEP 333
• Interface entre le web et une application
Python
Sunday, April 25, 2010

5. Serveur web
WSGI
Application Python
Sunday, April 25, 2010

6. simple application
def app(environ, start_response):
"""Simplest possible application object"""
data = 'Hello, World!n'
status = '200 OK'
response_headers = [
('Content-type','text/plain'),
('Content-Length', str(len(data)))
]
start_response(status, response_headers)
return iter([data])
Sunday, April 25, 2010

7. WSGI ?
• Réutilisation d’applications
• Middleware
• Paster
• Frameworks: webob, werkzeug, bottle,
repoze, ...
Sunday, April 25, 2010

8. Middleware WSGI
class CustomHeader(object):
def __init__(self, app):
self.app = app
def __call__(self, environ, start_response):
environ["HTTP_X_MY_HEADER"] = "1"
return self.app(environ, start_response)
Sunday, April 25, 2010

9. Serveur web
WSGI
Application Python
App App App
Sunday, April 25, 2010

10. Django & WSGI
Sunday, April 25, 2010

11. Intégrer
• Pourquoi réinventer la roue ?
• Principes communs: middlewares,
request, ...
• Réutiliser les applications.
• intégrer != compatible wsgi
Sunday, April 25, 2010

12. • django-wsgi
• twod.wsgi
Sunday, April 25, 2010

13. django-wsgi
• pas de dependance
• permet d’embarquer des apps wsgi,
`django_view`
• permet de creer une app wsgi à partir
d’une vue ou des urls, `wsgi_application`
Sunday, April 25, 2010

14. django_view
def test_app(environ, start_response):
start_response("200 OK", [("Content-type", "text/
html")])
yield "i suck"
def test_app1(request):
return HttpResponse("wowa, meta")
urls = patterns("",
..
(r"^test/$", django_view(test_app)),
(r"^(?P<name>.*?)/$", test_app1),
..
)
application = wsgi_application(urls)
Sunday, April 25, 2010

15. twod.wsgi
• vise à créer une "paserelle coopérative"
entre Django et WSGI
• basé sur webob (wrap HttpRequest et
HttpResponse)
• Paste deploy factory
• Middleware pour le routage
Sunday, April 25, 2010

16. twod.wsgi - embed
import os
from twod.wsgi import DjangoApplication
os.environ['DJANGO_SETTINGS_MODULE'] = "yourpackage.settings"
django_app = DjangoApplication()
Sunday, April 25, 2010

17. twod.wsgi routing args
(r'^/blog/posts/(?<post_slug>w+)/comments/(?
<post_comment_id>d+)$'
>>> request.urlvars
{'post_slug': "hello-world", 'post_comment_id': "3"}
Sunday, April 25, 2010

18. twod.wsgi - embed
• intégrer une application WSGI au sein de
votre projet django
• modifier les requêtes/réponses
• Integrer votre app django dans une app
WSGI
Sunday, April 25, 2010

19. embarque les apps
WSGI
from twod.wsgi import call_wsgi_app
from somewhere import wsgi_app
def run_app(request, path_info):
response = call_wsgi_app(wsgi_app, request, path_info)
response['Server'] = "twod.wsgi 1.0"
return response
Sunday, April 25, 2010

20. Déployer
• l’utilisation courante de Django avec WSGI
• 2 types de deploiements :
• via serveur
• via proxy
Sunday, April 25, 2010

21. Serveur
• uWSGI
• mod_proxy
Sunday, April 25, 2010

22. proxy
• spawning, paster, ...
• cherrypy, ..
• gunicorn
Sunday, April 25, 2010

23. Sunday, April 25, 2010

24. Sunday, April 25, 2010

25. gunicorn
• Green unicorn
• WSGI 1.0, clients lents et rapides
• supporte WSGI, Paster compatible app & ...
Django
• Load balancing via pre-fork and un socket
partagé
• Upgrade à chaud “à la nginx”
Sunday, April 25, 2010

26. mais encore...
• HTTP Stream. Décode le HTTP à la volée
• Gestion des connexions asynchrones
(longpolling, comet, websockets, appels
d’api, ...).
• Eventlet, Gevent, Tornado
• DSL Config
Sunday, April 25, 2010

27. Philosophie
• Simple
• Minimal
• Performant
• Unix
Sunday, April 25, 2010

28. Simple
• gunicorn_django -w 3 /myproject/
settings.py
• ./manage.py run_django -w 3
• gunicorn_django -w 3 -k
“egg:gunicorn#eventlet” /myproject/
settings.py
Sunday, April 25, 2010

29. Simple
• Taille memoire controllée
• Derrière NGINX
• Full Python
• Graceful Reload
Sunday, April 25, 2010

30. http://www.peterbe.com/plog/fcgi-vs-gunicorn-vs-uwsgi
gunicorn is the winner in my eyes. It's easy to configure
and get up and running and certainly fast enough [..] .
Sunday, April 25, 2010

31. DEMO
Sunday, April 25, 2010

32. 0.9
• Parseur HTTP en C (fallback en python sur
les plateformes non supportées)
• Increase unitests
• Reload hook
• status ?
Sunday, April 25, 2010

33. Liens
• http://gunicorn.org
• http://e-engura.org
• http://www.python.org/dev/peps/pep-0333/
• http://bitbucket.org/2degrees/twod.wsgi/
• http://github.com/alex/django-wsgi
Sunday, April 25, 2010

34. Questions
Sunday, April 25, 2010

35. @benoitc
Sunday, April 25, 2010

36. Cette création est mise à disposition selon le Contrat
Paternité 2.0 France disponible en ligne http://
creativecommons.org/licenses/by/2.0/fr/ ou par courrier
postal à Creative Commons, 171 Second Street, Suite
300, San Francisco, California 94105, USA.
Sunday, April 25, 2010