ø dowtime migrations - rubyconf 2015

Migrações em zero downtime com ruby.

Nesta apresentação mostro um pouco do mindset na RD para o rollout de novas features ou migrações sem downtime.

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