Django & BuildoutHorst Gutmann

zerok@zerokspot.com

Photo: http://flickr.com/photos/yakobusan/2363688612/http://creativecommons.org/licenses/by-nc-sa/3.0/at/

Django

• Web Framework in Python

• MVC

• ... has tons of great features that are actually not really relevant for the topic at hand

• Summary: <3

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Django and its libs

• What do we usually need ...

• Django

• django-tagging

• django-threadedcomments

• (if things like DB-bindings are already installed)

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All of that you have to install on ...

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• ... your own machine

• ... your server

• ... and basically every other machine that has anything to do with the development

Installing from & with ...

• Straight from an SCM-checkout

• Sadly that’s still very common since the apps are still quite young

• Using a setup.py

• Using setuptools and easy_install (PyPI <3)

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Being root helps

• You have to either install these libraries as root user

• ... or you have to start messing around with the PYTHONPATH

• ... which normally results in just a big mess

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virtualenv

• virtualenv lets you install Python packages without being root

• It lets you build environments for those packages that you load at will

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$ virtualenv myenv

$ source myenv/bin/activate

$ cd /some/lib

$ python setup.py install

....

$ deactivate

Photo: http://flickr.com/photos/fensterbme/145621388/

virtualenv

• ... is a great tool if you want to try a new library

• But it doesn’t solve the problem that you have to manually reconstruct the environment every time.

• The environments are not portable (C-extensions?)

• ... and not moveable (experimental right now)

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zc.buildout

• Buildout now lets you build a whole environment with just one config-file

• Basically, it’s similar to Maven in the Java-world, just without XML ;-)

• A project consists of multiple parts

• Each part defines, where its data is coming from and where to store it

9Photo: http://flickr.com/photos/mdpettitt/2521514631/

Recipes exist ...

• ... that download eggs and build a wrapped interpreter to test them

• ... that download a source-distribution and install it

• ... that checkout code from Subversion

• ... and much much more

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A small example

>>> buildout.cfg

[buildout]parts = sample

[sample]recipe = zc.recipe.eggsinterpreter = myinterpretereggs =

storm==0.12

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$ buildout

$./bin/myinterpreter> from storm.locals import *

PyPI Canonical

Buildout for Django

• What is in for Django developers?

• A simple way to install dependencies

• ... and to freeze them at a version

• ... and naturally really fast deployment (even with a WSGI-script)

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djangorecipe

• Recipe for Django projects by Jeroen Vloothuis: http://pypi.python.org/pypi/djangorecipe/

• Creates a Django project with a given version

• ... and creates a wrapper for manage.py with all eggs and other dependencies loaded

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Another example[buildout]parts = django svnapps

[django]recipe = djangorecipeversion = 1.0project = mysitesettings = settingsextra-paths = ${svnapps:location}/tagging

[svnapps]recipe = iw.recipe.subversionurls = http://django-tagging.googlecode.com/svn/trunk/ tagging

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import syssys.path[0:0] = [ '$HOME/.buildout/eggs/djangorecipe-0.12.1-py2.6.egg', '$HOME/.buildout/eggs/zc.recipe.egg-1.1.0-py2.6.egg', '$HOME/.buildout/eggs/zc.buildout-1.1.1-py2.6.egg', '$HOME/.buildout/eggs/setuptools-0.6c9-py2.6.egg', '$HOME/tmp/buildout2/parts/django', '$HOME/tmp/buildout2', '$HOME/tmp/buildout2/parts/svnapps/tagging', ]

import djangorecipe.manageif __name__ == '__main__': djangorecipe.manage.main('mysite.settings')

./bin/django

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mod_wsgi?

• djangorecipe can also be used to create a WSGI-script

• Option: wsgi = true

• ./bin/django.wsgi

• Naturally also includes all the dependencies

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Summary

• Buildout provides easy dependency management from a multitude of sources (public or not and not only with setuptools)

• Dependencies AND freezing of them

• For developing on a Django project all you need is one buildout.cfg

• djangorecipe also provides you with a WSGI-script

• Migrating to it is very easy :-)

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Some links

• http://www.djangoproject.com

• http://pypi.python.org/pypi/zc.buildout/

• http://pypi.python.org/pypi/djangorecipe/

• Icons: http://graffletopia.com/stencils/144

• Pony: http://djangopony.com

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