1. Django Deployment
{ Tips, Tricks and Best Practices

2.  You mission, should you choose to accept it:
 Make your application run with 1 click,
everywhere it counts, every time.
 Make your application run exactly the same way,
everywhere it counts, every time.
 Prove that the above are true.
Reproducibility

3.  Reproducible Infrastructure
 Reproducible Systems
 Reproducible [Django] Applications
 Dependencies
 Configuration
 Data
 Deployment
Steps to Reproducibility

4.  Systems: Virtual or Physical
 Power Management
 Console
 Backup / Restore
 Network Layer
 Load Balancing
 Security
 Performance
Infrastructure

5.  A Stable Foundation
 Stable Operating System
 Reproducible Installation
 Kickstart Install
 Base Image
 Configuration Management
 Puppet, Chef
 Packaging
Systems

6.  What Python?
 How will you install packages?
 How will you make it reproducible?
 Database?
 Backup / Restore
 Failover
 Performance
 Caching?
 HTTP
 Objects
 Queuing?
 SSL?
Application Environment

7.  It’s just code, right?
 Probably Not
Application

8.  Just use pip! lib/pypi-cache:
Django-1.4.3.tar.gz
 Not so fast.
 Lots of external requirements.txt:
dependencies Django==1.4.3
 Eliminate them
with a local Type this:
pip install --no-index --find-links
cache
file://$(PWD)/lib/pypi-cache -r
 Don’t’ forget requirements.txt
virtualenv!
Dependencies

9.  settings.py settings.py:
 No logic allowed! from urlparse import urljoin
 ‚unknown‛ from os import environ
import times import dj_database_url #courtesy of Heroku
 Critical
 Local_settings.py DATABASES =
 More of the same dj_database.config(default=‚xxx‛)
BASE_URL = environ*‘DJANGO_BASE_URL’+
 Consider pushing STATIC_URL = urljoin(BASE_URL, ‘static’)
configuration in MEDIA_URL = urljoin(BASE_URL, ‘media’)
externally via
environ, Run this:
configparser, etc DJANGO_BASE_URL=http://cdn.com/base/
django-admin.py runserver
Configuration

10.  Fixtures. Consider fixtures/polls.py:
writing them in from ..models import Poll, Choice
def apply():
Python! p = Poll.objects.get_or_create(q=‘test q’,
 Testable defaults=dict(pub_date=‘1980-01-01))
c1 = Choices.objects.get_or_create(poll=p,
 More resilient to
choice_text=‘option 1’)
change
 Less pk pain fixtures/tests/test_poll.py:
Class PollFixtureTestCase(TestCase):
def test_fixture_applied():
 Migrations! self.assertEquals(Poll.objects.get(q=‘test q’)
 Test them
Application: Database

11. management/__init__.py:
from django.db.models.signals import post_syncdb
from south.signals import post_migrate
from .. import models, fixtures
def update_poll_fixtures(verbose=True):
fixtures.poll.apply()
if verbose:
print "Updating dynamic fixtures for profile”
def update_fixtures_post_syncdb(sender, **kwargs):
update_poll_fixtures()
def update_fixtures_post_migrate(app, **kwargs):
if app == ’polls':
update_poll_fixtures()
post_syncdb.connect(fixtures_post_syncdb, sender=models)
post_migrate.connect(fixtures_post_migrate)

12. Interwebs
 Back Up Everything!
 Move files to Green
 Fabric?
 RPM?
 Tar?
 Git?
 Rsync?
App App Deploy / Test
 Update Stuff
 syncdb
 apply fixtures
 Test Green!
 Flip/Flop Blue/Green Data
 (Roll back to Blue)
Deployment: Blue/Green

13. Erik LaBianca, WiserTogether, Inc.
erik.labianca@gmail.com
@easel
https://linkedin.com/in/eriklabianca/
https://slideshare.net/easel1/
https://github.com/easel/
https://github.com/WiserTogether/
Questions?