At Tuenti, we do two code pushes per week, sometimes modifying thousands of files and running thousands of automated tests and build operations before, to ensure not only that the code works but also that proper localization is applied, bundles are generated and files get deployed to hundreds of servers as fast and reliable as possible. We use opensource tools like Mercurial, MySQL, Jenkins, Selenium, PHPUnit and Rsync among our own in-house ones, and have different development, testing, staging and production environments. We had to fight with problems like statics bundling and versioning, syntax errors and of course the fact that we have +100 engineers working on the codebase, sometimes merging and releasing more than a dozen branches the same day. We also switched from Subversion to Mercurial to obtain more flexibility and faster branching operations. With this talk we will explain the process of how code changes in ourcode repository end up in live code, detailing some practices and tips that we apply.

1. Release Workflow
Diego Muñoz
diego@tuenti.com
http://twitter.com/Kartones

2. Agenda
• Some numbers
• Release workflow
• Some tools
• Some rants

3. Some numbers
• +12M users
• +100 usage minutes / day (avg)
• +200M chat messages / day
• +4M photos uploaded / day (peaks)
• +40,000M page views / month
• +35K requests / sec (peaks)
• +1K servers
• +250 employees (~60% techies)
• +15K files in the repositories
• +8K Tests

4. Release Workflow
Branch Code Test Integrate Release Stabilize

5. Release Workflow: Branch
Branch Code Test Integrate Release Stabilize
• 8-12 branches per release
• Current record: 29 branches
• Repository per functional area (be, fe, stats, …)
• Avg. # lines modified per release: 63K

6. Release Workflow: Code + Test
Branch Code Test Integrate Release Stabilize
• Scrum (or at least Agile)
• As TDD as possible
• Labs
• A/B Testing
• PoCs
• Dark launch

7. Release Workflow: Integrate
Branch Code Test Integrate Release Stabilize
• Repo always available
• Only merge with 100% tests ok / TFW approval
• QA Regression & manual tests
• Fix possible merge/integration problems ASAP

8. Release Workflow: Release
Branch Code Test Integrate Release Stabilize
• 2 releases per week (tuesdays & thursdays)
• Latest stable changeset from Integration taken
previous day 11 AM
• Release doc, pre-release meetings
• Staging servers to test with live data
• We are searching for a Release Manager ;)

9. Release Workflow: Stabilize
Branch Code Test Integrate Release Stabilize
• First code push: 8 AM
• Release window: 3 hours (normal scenario)
• Live error stabilization or rollback
• Representatives from all involved teams

10. Some tools

11. DVCS: Mercurial
• http://mercurial.selenic.com/
• Syntax similar to SVN (our old system)
• Easy API to plug our plugins and hooks
• 100% cross-platform (now Git also but not before)
• Commit hooks to check syntax, coding standards…
• Bottleneck:
– Push/pulls through VPN are slow

12. Issue Tracking: Trac
• http://trac.edgewall.org/
• User Stories tasks
• Bugs
• Wiki
• Plugins and extensible
• Bottleneck: Sometimes slow, code viewing not
optimal

13. Testing: PHPUnit
• http://www.phpunit.de
• Some caveats
– Mocking just ‘works’
– PHP process spawning PHP tests
• We have:
– Vastly improved mocking framework
– Shell scripts that isolate test batteries
– Better integration with Selenium
• Bottleneck: Our current FEFW does not cope
perfectly with PHPUnit/Selenium

14. CI: Jenkins
• http://jenkins-ci.org/
• Previously Hudson too
• CI servers farm
• Parallelization, plugins, special reports, custom
tunnings
• Bottleneck: Acceptance tests

15. Storage: MySQL
• Live site storage
• Dev. env. storage
– 1 DB per user (to run tests)
– 1 shared DB (common faked data)
• Bottleneck: Slow when running tests

16. File copying: RSync
• http://rsync.samba.org/
• Deployment of code (live & dev)
• Sends deltas/diffs
• Really fast

17. Configuration: Puppet
• http://puppetlabs.com/
• Production machines
• Jenkins nodes
• VM management / Dev web servers config

18. Stats: Hadoop
• http://hadoop.apache.org/
• Dedicated cluster
• HBase
• Hive

19. VirtualBox
• https://www.virtualbox.org/
• Multi-platform
• Accurate and fast emulation of Windows OS
• Bottleneck: RAM of host machine

20. Search: Sphinx
• http://sphinxsearch.com/
• Non-realtime (index based)
• Very fast
• Bottleneck: Index generation on dev & test env.

21. Caching: Memcached
• http://memcached.org/
• Dev. Behaviour == live behaviour
• Tuenti has sent improvements & patches
– UDP patch, random ports
• Bottleneck: 32GB RAM / machine practical limit

22. Some rants

23. Statics versioning: The good
• Browser caching problems gone
• Transparent & easy to use by developers
• Easy to deactivate for testing

24. Statics versioning: The bad
• Dangerous if not careful with non-
production ready files
• Waste of bandwith
• No dev versioning == browser caching
problems

25. File bundling: The good
• Less files == faster download & deploy
• Big text file == better HTTP Gzip
• Build time only (no need for dev)
• Combines perfectly with minification and
versioning

26. File bundling: The bad
• Firebug debugging harder (big single files)
• One syntax error breaks multiple bundled files
– Minimized + Bundled + Error == Real pain
• Hierarchy needed to avoid bundling multiple
times same files.
– Web, external/public page, mobile…
• Dev. only errors !

27. Our Build script
• Localization
• Minification
• Bundling
• Versioning
• Statics deployment to CDNs
• Deltas of changes or full build
• …
• Bottleneck: Build time

28. HipHop
• Migrating old code to fully support HipHop
– With PHP 5.3
• Obvious speed improvements
• Also nice for static code analysis

29. Our Chat
• Erlang (server) + Javascript (client)
• Jabber protocol
• Ejjabberd tweaked (3,5x faster)
• 200M msgs/day, 1M concurrent users peak,…
• 20 machines, ~5 instances per machine
• Same behaviour dev/live is critical
• We’re searching for Erlang experts ;)

30. exit(0);
Sounds interesting?
http://jobs.tuenti.com