At Preply we have adopted the culture of quick iterations as a central part of our delivery process. The approach impacted both developers' culture and organization's ability to deliver value to the end customers. This talk will be focused around the evolution we went through with our delivery approach, and the benefits and challenges daily releases have thrown up. We will also discuss tooling around daily releases (CI/CD tools, logging, monitoring), infrastructure(k8s, aws) and the best practices (feature switchers, architecture, ab/testing). We will also share insights on the role of the performance optimizations to make daily releases viable

1. 100 Releases a Day
Dmytro Voloshyn
CTO at Preply

2. Global marketplace
for online language
tutoring.

3. Releases are the heartbeat of the
company
• More frequent releases mean smaller
features means more safety
• Less context switch for devs
• Quicker results for business
• Organization becomes more agile
• We love Friday deploys*
*https://charity.wtf/2019/05/01/friday-deploy-freezes-are-exactly-like-murdering-puppies/

4. 1. History
2. Current stack
3. Enablers
4. Challenges
Todays plan

5. History

6. Branching model: 2012-2015

7. Deployment: 2012-2015
• deploy.sh on ec2 server via
ssh
• manual testing on stage

8. Branching model: 2016-2018

9. Deployment: 2016-2018

10. Deployment 2016-2018

11. Deployment: 2016-2018

12. Current stack

13. Branching model: 2018-2019
https://trunkbaseddevelopment.com/

14. Deployment: 2019: staging

15. Deployment: 2019: staging
https://medium.com/preply-engineering/

16. Deployment: 2019

17. Enablers
• Features switchers
• Code reviews
• Quality gates
• Tooling
• Culture

18. Enablers: Feature switchers
• Synchronized between envs
• Flexible, but 1-liners
• Cleanup process
• Quick

19. Enablers: quick code reviews

20. Enablers: Quality gates
• Linters
• Migrations checks
• Localization checks
• Unit/Integration/e2e test
• Schema checks/versioning

21. Enablers: Quality gates: schema
https://apollographql.com

22. Tooling: Alerting: Prometheus + Alert Manag.

23. Tooling: Exception management: Sentry

24. Enablers: Culture
• Structure of the code should reflect org. chart
• Full cycle ownership
• Trust
• A/B testing culture

25. Challenges
• Instable CI/CD
• Flappy tests
• New services
Monolyth new µ-service

26. We are always hiring!
https://preply.com/en/careers

27. Thanks!
/in/dmytrovoloshyn
dmytro@preply.com
Dmytro Voloshyn
https://www.facebook.com/dmytriy.voloshyn