ø dowtime migrations - rubyconf 2015

Transcript

1. ø downtime Jônatas Davi Paganini jonatas jonatasdp

2. 8 dev teams

3. 10 deploys / day

4. RD Station

5. +2m mail / day

6. +700 external services integrations

7. +N callbacks

8. Availability is REQUIRED

9. 99,9% 99,5% 99,0% 98,6% 98,0% 97,0% 99,99% 00:43:00 03:36:00 07:12:00

   10:00:00 14:24:00 21:36:00 00:04:32 Availability

10. 99.999???

11. availability = ( total_time - timeout / total_time ) *

    100

12. ø downtime

13. mindset

14. NO schedule maintenance

15. avoid: all || nothing

16. build reversible things

17. build incremental migrations

18. RubyConf 2012

19. compatible versions

20. http://shipit.resultadosdigitais.com.br/blog/ migrando-com-zero-downtime talk is <cheap>!

21. show me the code!!!

22. Migration add_column :people, :full_name, :string

23. Update data Person.all.each do |person| person.full_name = "#{person.first_name} #{person.last_name}" person.save

    end

24. 350 million updates!!!

25. WTF time?!

26. Let’s improve it! Person.all.each do |person| person.full_name = "#{person.first_name} #{person.last_name}"

    person.save end

27. Select RIGHT attributes!

28. Update 0.1 Person.select("id,first_name,last_name").each do |person| person.full_name = "#{person.first_name} #{person.last_name}" person.save

    end

29. update_attribute instead of save

30. Update 0.2 Person.select("id,first_name,last_name").each do |person| person.update_attribute "full_name", "#{person.first_name} #{person.last_name}" end

31. find in batches

32. avoid transaction overhead

33. Update 0.3 Person.select("id,first_name,last_name").find_in_batches do |people| People.transaction do people.each do |person|

    person.update_attribute "full_name", "#{person.first_name} #{person.last_name}" end end end

34. FAILURE resilient

35. Update 0.4 Person.where(full_name: nil).select("id,first_name,last_name").find_in_batches do |people| People.transaction do people.each do

    |person| person.update_attribute "full_name", "#{person.first_name} #{person.last_name}" end end end

36. explore connection pool

37. Update 0.5 update_sql = "UPDATE people set full_name =" Person.where(full_name:

    nil).select("id,first_name,last_name").find_in_batches do |people| People.transaction do people.each(ActiveRecord::Base.connection_config[:pool]) do |person| ActiveRecord::Base.connection_pool.with_connection do |conn| set_full_name = conn.quote("#{person.first_name} #{person.last_name}") conn.execute("#{update_sql} #{set_full_name} where id = #{person.id} ") end end end end

38. model hook

39. Model class Person < ActiveRecord::Base before_save :update_full_name def update_full_name self.full_name

    = "#{first_name} #{last_name}" end end

40. rollout control

41. Rollout class Rollout def enabled?(feature, context) redis.sismember(feature, context) rescue Redis::BaseError

    false end def enable(feature, context) redis.sadd(feature) end def disable(feature, context) redis.srem(feature) end private def redis Redis::Namespace.new("rollout", redis: $redis) end end

42. rollout use

43. if: before_save :update_full_name, if: -> { Rollout.enabled? "started_migration", "global" }

44. deploy steps

45. smoothly steps

46. PR #1 add new column

47. PR #2 write old & new columns

48. PR #3 migrate data

49. PR #4 read from new column

50. PR #5 remove old column

51. PR #6 remove rollout code, cache

52. Conclusion

53. Embrace migrations • smoothly • incremental • safe • resilient

54. Avoid migrations • all || nothing • ! roll outable

    features

55. REFERENCES blog.codeship.com/rails-migrations-zero-downtime/ shipit.resultadosdigitais.com.br/blog/migrando-com-zero-downtime/ confreaks.tv/videos/railsconf2012-zero-downtime-deploys-for-rails-apps

56. ?

57. Thanks! jonatas jonatasdp ideia.me shipit.resultadosdigitais.com.br