Talk apresentada no 21o RubyFloripa contando como foi a experiência em assumir uma app legada Rails e introduzir Elixir. Utilizando tecnologias como GenStage, AWS SQS e SNS.

1. 21o. RubyFloripa
sponsor supported byhosted by
Maintaining legacy Rails app and introducing Elixir

2. CTO at
You can find me:
@wevtimoteo$ whoami

3. Disclaimer
● Personal experience
● This might be a technical talk
● Will be a pleasure to answer any questions

4. The scenario
● Outdated Ruby version
● Outdated Rails version
● No monitoring
● No tests
● No standards/styleguide
● No documentation
● No one to ask
● No development process
● No visibility about mobile apps
● No QAs
● A lot of Bugs and Expedites

5. Bug cost

6. What should I do first?
1. Action!

7. Extreme Programming Values
● Simplicity
● Feedback
● Respect
● Communication
● Courage

8. Challenge
● Fix API endpoints
● Fix broken controller actions
● Fix reports
● Fix broken features in mobile
apps
● Implement new features
A lot of
FIXES

9. Visibility - App Health
● Errbit (Airbrake DSL)

10. Security and Safety
● Freeze gem versions
● Introduce QA
environment
● Update Rails to 3.2.22.5
● Update Ruby to 2.2.6

11. Organization and Ownership
● Change keys used in project
such 3rd party services
(Google Maps)
● Migrate files stored in
consulting S3 buckets
● Reorganize used gems in
Gemfile
● Setup test suite

12. Danger: No Tests!

13. Development process

14. Backlog

15. Development environments

16. The Dev Team
Leandro HeuertWeverton
Timoteo

17. Mobile apps monitoring

18. Why Elixir?
● Reliability
● Concurrency
● Performance
● Scalability

19. Elixir: Cons
● Fewer Libraries
● Learning curve

20. Learning
● Elixir Lang
● Elixir School
● Hex docs
● Programming Elixir by Dave
Thomas

21. Sharing Ruby code with Elixir
● ErlPort
● Erlectricity
● Erlix

22. Ecto + MongoDB
● Database wrapper
● Data mapping

23. Background services

24. AWS SNS/SQS

25. GenStage and SNS/SQS
● Pipeline with independent
stages
● Consumer + Producer
● Data Transformation
Pipeline
● Work Queue
● Event Processing

26. Package Manager? Hex

27. ExRoads: Google Roads Wrapper

28. Snap to Roads

29. Releasing it

30. Elastic Beanstalk

31. Dockerizing

32. Dockerizing pt 2

33. Tracking exceptions

34. Technologies

35. Next steps
● Implement end2end
(acceptance) tests
● Upgrade to Rails 5
● Setup autoscaling
● Multiple consumers and
producers in GenStage
● Kubernetes?
● Kibana and Logstash
● Database Cleaner for Workers
tests?

36. Thank you!
Questions?

37. ● Elixir Lang
● Elixir School
● Programming Elixir by Dave Thomas
● GoogleRoads
● GenStage docs
● Distillery
● Beanstalk docs
● Docker multistage build
● How to use Ruby code inside Elixir (Elixir SC
Meetup)
References