Continuous deployment. The same thing as continuous delivery for our purposes here.
Being able to deploy every good version of your software.
More than technology: techniology for automation, people, environment.
Fail fast, win fast; competitive advantage; real-time control; pivoting, etc.
Have a single path to production; optimising for resilience. “If it hurts, do it more often.” Automate as much as possible.
- Use vagrant to develop on as close to live as possible.
- Develop, test, commit.
- Run a build: unit tests, static analysis, coverage. Very fast.
- Iff: functional tests, integration tests.
- Iff: deploy to staging, test migration, smoke and UI tests.
- Iff: you can push the deploy button.
- Then: goes to production.
- Users are happy.
- Measure, monitor, analyse.
- Learn from the information and feedback into the loop.
Environments
Make all environments look the same, minimising differences minimises
surprises. Use vagrant to provision virtual boxes (configured in similar
ways to staging and live environments).
Having a repeatable, versioned configuration. Use Puppet, Chef, shell scripts, whatever. Just use something.
“Snowflake” servers (every one precious and unique) are bad, “phoenix” servers are the goal.
Use Puppet for provisions and OS and services; Fabric for scripted tasks.
Use virtualenv and pip. Make all your configuration as code.
Use South for schema and data migrations. Split your expansion and contraction columns: only drop the old columns after everything is working correctly in production.
Testing
Using Django’s testing framework, driven by Jenkins. There’s a django-jenkins plugin.
Use factory_boy to generate testing data.
Test separation: don’t run slow or flaky tests every build.
Build
One way to build and deploy; all developers fit into the same process. Make “don’t deploy broken code” easier;
Deploy
- django-dbbackup
- pull()
- apply_puppet()
- django-extensions
- syncdb
- collectstatic
Use feature flags. Gargoyle or Waffle in Django.
Monitor
- Errors go into Sentry.
- Munin
- NewRelic
- django-statsd
Rollback
Having some way to recover from bad or failed builds.