Lessons Learned

How to launch a product using Scala.

Feb 25, 2017 at Scala Matsuri 2014 in Tokyo, Japan.

Transcript

1. How to launch a new product using Scala Lessons Learned Yoshimasa Niwa Feb 25, 2017 in Tokyo αʔϏεΛθϩ͔Β࡞ͬͯେ੾ͩͬͨͭͷ͜ͱ
2. @niw Yoshimasa Niwa
4. California, USA San Francisco αϯϑϥϯγεί͔Β͖·ͨ͠ɻ
7. that we’ve launched. Products θϩ͔Βͭͬͨ͘ϓϩμΫτͷ঺հ
8. Search GIF and instantly Tweet it. GIF Button (*'
   Ϙλϯػೳ
10. Unleash your creativity by adding fun Stickers. Stickers εςοΧʔػೳ
13. How to launch a product using Scala Lessons Learned I was (am) not a Scala specialist. Launched user facing products using Scala. There are many lessons I’ve learned. αʔϏεΛθϩ͔Β࡞ͬͯେ੾ͩͬͨͭͷ͜ͱ
14. Today’s talk At glance History, we’re learning from history. Architecture, that built from the lessons. Implementation, that we’re using. Executions, form what I’ve learned lessons. ຊ೔ͷ࿩ͷ֓ཁ
15. A short history behind that whale. History γεςϜ͕ࠓͷΑ͏ʹͳΔ·Ͱʹ͸ྺ࢙͕͋Γ·ͨ͠ɻ
16. in 2009. The biggest Ruby on Rails application 5XJUUFS
    ͸
    ੈքͰ͓ͦΒ͘࠷΋େ͖͍
    3VCZ
    PO
    3BJMT
    ͷΞϓϦͰͨ͠
19. So it called “Monorail.” Many pains in the large monolithic system • It’s really easy to break someone’s modules. • grep(1) is the only tool we can believe. • Deploy everything, revert everything. ڊେͳ୯ҰͷγεςϜͰ͸ਏ͔ͬͨɻ
20. into small services in Scala Decompose monolithic system ڊେͳ୯ҰͷγεςϜΛ෼ղͯ͠
    4DBMB
    Ͱ࠶࣮૷͍ͯͬͨ͠
21. to decompose monolithic Ruby on Rails application Rewrite each module in Scala class User < ActiveRecode::Base
 def self.find(...)
 $user_service.find(...)
 end
 end User.find(1) #=> #<UserServiceUser: ...> ڊେͳ
    3VCZ
    PO
    3BJMT
    ΞϓϦέʔγϣϯΛ෼ղͯͦ͠ΕͧΕͷϞδϡʔϧΛ
    4DBMB
    Ͱ ॻ͖௚ͨ͠ɻ
22. into a single system. Compose each small service ෼ղͨ͠αʔϏεΛ߹੒ͯ͠ɺγεςϜͱͯ͠ػೳ͢Δ
23. Deal with complexity “Functional” Architecture ʮؔ਺తͳʯΞʔΩςΫνϟͰɺෳࡶͳ࢓૊ΈʹରԠ͢Δɻ
24. Goal is managing complexity. System is complex γεςϜ͸ͱͯ΋ෳࡶɻͦͷෳࡶ͞Λ͍͔ʹ؅ཧ͢Δ͔ͱ͍͏ͷ͕ΰʔϧɻ
25. Example code System is complex def main(args: Array[String]) {
 args match {
 case Seq("command1") =>
 ...
 case Seq("command2") =>
 ...
 case Seq("command3") =>
 ... // Continue 10,000 lines
 }
 } ෳࡶͳίʔυͷྫ
26. Divide-and-rule Separate interests and responsibilities ෳࡶͳγεςϜ͸෼ׂ౷࣏ɻॲཧͷର৅ͱ੹೚Λ෼ׂɻ
27. Divide-and-rule. System is complex def func1() {
 ...
 } def func2() {
 ...
 } def func3() {
 ...
 } def main(args: Array[String]) {
 args match {
 case Seq("command1") =>
 func1()
 case Seq("command2") =>
 func2()
 case Seq(“command3") =>
 func3()
 ...
 }
 }
 ෳࡶͳίʔυΛந৅Խͯ͠෼ׂͨ͠ྫ
28. Getting request and returning response. Service is a function αʔόʔ͸ɺͭ·Γؔ਺ɻϦΫΤετΛҾ਺ʹͱͬͯɺϨεϙϯεΛฦ͢ɻ def service(
 request: Request
 ): Response
29. Create new functions in the system. Create a new service ৽αʔϏεΛ࡞Δ
    ʹ
    γεςϜʹ৽͍ؔ͠਺Λ௥Ճ͢Δ def service(
 request: Request
 ): Response def newService(
 request: Request
 ): Response
30. Response is not always available immediately. In real world, however. def service(request: Request): Response = ... // How slow is this?
 val reposes = service(request)
 ݱ࣮ʹ͸ɺ͔͠͠ɺؔ਺ͷ஋͸ଈ࠲ʹखʹೖΔΘ͚Ͱ͸ͳ͍ɻ
31. We need to wait. Everything is asynchronous ͢΂ͯ͸ඇಉظɻ଴͕ͪ࣌ؒ͋Δɻ
32. Example GIF Button (*'
    Ϙλϯͷ৔߹ Loading Successful Failed
33. A capsule of the value Option[+A] ? ஋Λ͍ΕΔͱ͍͑͹ɺ0QUJPO< ">
    +A Option Value Some None
34. A capsule of the value Future[+A] ͋Δ஋͕औΓ͏Δঢ়ଶΛ
    'VUVSF
    ͰแΜͰ͓͘ +A Future ? Value Exception Pending Successful Failed
35. Example Future[+A] def func(a: String): Future[String] = … def main(args: Array[String]) {
 // This call is not blocking.
 val future = func(args.head)
 
 // Do awesome things...
 
 // Wait until reply is defined
 println(Await.result(future))
 }
 ྫ͑͹ɺ͜͏͍͏ײ͡ʹͳΔɻ
36. Getting request and reply in Future. Service[-Req,+Rep] αʔϏε͸ϦΫΤετΛड͚औͬͯɺϨεϙϯεͷ
    'VUVSF
    Λฦ͢ɺͱॻ͚Δɻ Req => Future[Rep] Rep Req Waiting… Response Exception Pending Successful Failed
37. Future works same as the other capsules. Compose Future[+A] • map[A,B](A => B): Future[B] • flatMap[A,B](A => Future[B]): Future[B] • join[A,B](Future[A], Future[B]):
 Future[(A,B)] • collect[A](Seq[Future[A]]): Future[Seq[A]] 'VUVSF
    ͸ଞͷ
    4DBMB
    ͷίϨΫγϣϯͱಉ༷ʹ߹੒Մೳɻ A Future[A] B Future[B] map A Future[A] B Future[B] flatMap
38. Example Compose service calls val userRepo: Service[Long, User] = ...
 val profileRepo: Service[User, Profile] = ...
 val postRepo: Service[User, Seq[Post]] = ...
 userRepo(userId).flatMap { user =>
 Future.join(
 profileRepo(user),
 postRepo(user)
 ).map { (profile, posts) =>
 renderResponse(profile, posts)
 }
 } αʔϏεͷ݁Ռ͸
    'VUVSF
    ͔ͩΒɺݺͼग़͠Λ࣍ʑ߹੒Ͱ͖Δɻ
39. class GifSearchHandler {
 def apply(request: SearchRequest):
 Future[SearchResponse] = for {
 user <- userRepo(request.user_id)
 results <- Future.collect(
 gifRepos.map { repo =>
 repo(request.query, user.lang)
 }
 )
 } yield merge(results) } GIF Button Example ྫ͑͹
    (*'
    #VUUPO
    ͷݕࡧॲཧ͸͜Μͳײ͡
40. Deal with complexity “Functional” Architecture Divide-and-rule Function as a service Compose response Future[+A] to make a logic asynchronously ʮؔ਺తͳʯΞʔΩςΫνϟ
41. Things we need to build services Implementation αʔϏεΛ࡞Δͷʹඞཁͳ࣮૷
42. • Define functions • Resolve functions • Implement functions • Instantiate functions • Discover functions Things we need to call function γεςϜ͕ඞཁͱ͍ͯ͠Δ͜ͱ
43. Thrift, an IDL to define models and services Scrooge, a Thrift code generator in Scala Thrift, Scrooge Define functions ఆٛʹ͸
    5ISJGU
    Λ࢖͏ɻ4DSPPHF
    Ͱ
    4DBMB
    ͷίʔυੜ੒ɻ
44. Resolve functions Mono repo Git, “special version” Faster clone Pants, a build system for mono repo. ੩తͳґଘؔ܎͸ϞϊϨϙͱ1BOUT
    ϏϧυγεςϜͰղܾ
45. Finagle, a RPC core library. Finatra, a framework using Finagle TwitterServer (HTTP server and Thrift server) Guice dependency injection Finagle, Finatra Implement functions ࣮૷ʹ͸
    'JOBHMF
    Λϕʔεʹ
    'JOBUSB
    Λ࢖͍ͬͯΔ
46. Instantiate functions Mesos, Aurora Mesos, a cluster manager for data center. Aurora framework, a job scheduler. Define job in aurora DSL file. .FTPT
    ͱ
    "VSPSB
    ϑϨʔϜϫʔΫͰΠϯελϯεΛ؅ཧ
47. Discover functions Zookeeper Zookeeper, a reliable directory for service discovery. Announced by Aurora Resolved by Finagle ;PPLFFQFS
    ͰαʔϏεΛൃݟ͢Δɻ"VSPSB
    ͰΠϯελϯεΛ໊લొ࿥ͯ͠ɺ'JOBHMF
    Ͱղܾ
48. .scala .thrift .aurora .scala .thrift .aurora Git .scala .thrift .aurora Mesos Aurora Zookeeper /s/gifsearch Instance Instance
49. Things we need to build services Implementations Define in Thrift, manage every things in a single Git repository. Finatra to implement services. Aurora to run services and discovery. αʔϏεΛ࡞Δͷʹඞཁͳ࣮૷
50. Executions Let’s talk about making things. ੡࡞ਐߦʹ͍ͭͯ
51. We’re a team Engineers, product manager, and designers works in a team. ΤϯδχΞɺϓϩμΫτϚωʔδϟɺσβΠφ͕ɺͻͱͭͷνʔϜͰ࢓ࣄ͠·͢ɻ
52. P Product Manager D Designer E Engineer Design Plan Implement
53. Engineers have different responsibilities than Product Managers Product vs. Engineering ϓϩμΫτରΤϯδχΞϦϯά
    ΤϯδχΞ͸ϓϩμΫτϚωʔδϟͱ͸ҧ͏੹೚͕͋Δ
54. P Product Manager D Designer E Engineer Design Plan Implement
55. Maximize meeting product requirements Minimize tech-debt ϓϩμΫτͷཁٻʹ౴͑ͭͭɺٕज़తͳෛͷҨ࢈ΛݮΒ͢ɻ
56. Integrate everything at first. Build app from top to bottom Bad assumption may increase tech-debt. Right assumption may reduce tech-debt. Reduces many bad assumptions. ·্͔ͣΒԼ·Ͱͱʹ͔͘ܨ͍Ͱಈ͔͢ɻ૝ఆΛͰߟ͑Δ͜ͱΛͰ͖Δ͚ͩݮΒ͢ɻ S S S S S Service Service Service Service Service
57. Create many instances with modification on Aurora Run devel instances Work-in-progress instance is okay. Working mock is better than tech-doc to deal with product manager, sometimes. ։ൃ༻ΠϯελϯεΛ࣮ߦ͓ͯ͘͠ɻ
58. Override services for debugging and testing Dtab A delegation table. Override finagle resolver to swap services. Dtab-local: header for HTTP request. %UBC
    Λ࢖໊ͬͯલղܾΛ্ॻ͖ͯ͠αʔϏεΛϥϯλΠϜʹೖΕସ͑Δ
59. Naming and Dtab Naming /s/gifsearch /s/prod/gifsearch /zk/zk.domain:2181/prod/gifsearch /$/com.twitter.serverset/zk.domain:2181/prod/ gifsearch αʔϏεͷ໊લղܾͱ
    %UBC
60. Naming and Dtab Naming /s/gifsearch /s/prod/gifsearch /s/devel/gifsearch /zk/zk.domain:2181/devel/gifsearch /$/com.twitter.serverset/zk.domain:2181/devel/ gifsearch αʔϏεͷ໊લղܾͱ
    %UBC /s/prod/gifsearch
 =>/s/devel/gifsearch;
61. Deal with anomalies and exceptional cases Design vs. Engineering σβΠϯରΤϯδχΞϦϯά
    ྫ֎ʹ͍͔ʹରԠ͢Δ͔
62. P Product Manager D Designer E Engineer Design Plan Implement
63. by maintain the application state. Reduce exceptional cases ΞϓϦέʔγϣϯͷঢ়ଶ؅ཧΛͯ͠ྫ֎ΛݮΒ͢ɻ
64. are user facing and used by human beings. iOS and Android clients ϞόΠϧΫϥΠΞϯτ͸ਓ͕͔ؒͭ͏΋ͷɻ༧ଌ֎ͷૢ࡞Λ͞ΕΔ͜ͱ΋͋Δɻ
65. User interface is a representation of internal states. Manage internal state. Users changes the internal state. React to the internal state changes. Applying animation, if needed. ಺෦ঢ়ଶͱมߋͷྲྀΕΛ؅ཧ͢Δɻ6*͸಺෦ঢ়ଶΛදݱ͢Δ΋ͷɻ S Action State Change UI Update Action U User
66. Communication between teams and services Engineering vs. Engineering ΤϯδχΞϦϯάରΤϯδχΞϦϯά
    νʔϜಉ࢜ͷ΍ΓͱΓ
67. P Product Manager D Designer E Engineer Design Plan Implement E Engineer nt Im plem ent
68. Truth is in front of you as a code. Read code ৴͡ΒΕΔ΋ͷ͸ιʔε͚ͩɻ
69. Single “source” of truth. Mono repo helps it. Identify exact source code by deploy SHA-1. Browse entire source code that the system is using. ୯ҰιʔεϨϙδτϦͰਅ࣮ΛݟΔ commit 8270324cdf0d1e60a83dbefa1de29d89f6107587
 commit f40648b9105f7478139694acd0821c15d3315dc2
 commit fa0dc865887a02b49576bdc1de57f4ad802d4710
 commit ebf31743cbe3008ec311d88aea42b987b0288cd3
70. Name tells what it is. Define right functions Define API in reasonable way. Naming is really really important. They never read tech-doc. ਖ਼͍ؔ͠਺ͷఆٛ͸υΩϡϝϯτΑΓେ੾ɻ outputImageProviderFromBufferWithPixelFormat:pixelsW ide:pixelsHigh:baseAddress:bytesPerRow:releaseCallba ck:releaseContext:colorSpace:shouldColorMatch:
71. Manage dependencies. Downstream Estimate QPS and latency. Right timeout and retry policy. Right load banaler ApertureLoadBalancer for lower QPS 214ͱϨΠςϯγΛ؅ཧɻϥΠϜΞ΢τͱϦτϥΠͷௐ੔ɺϩʔυόϥϯαͷௐ੔ɻ S S S S S Service Service Service Service Service
72. Manage dependencies Upstream Look at CancelledRequestException. Upstream timed out for downstream, it will cancel request and downstream will see this exception. $BODFMMFE3FRVFTU&YDFQUJPO
    ʹ஫ҙɻ
    6QTUSFBN
    ͕ݫ͍͠λΠϜΞ΢τΛ࣋ͬͯΔՄೳੑ͋Γɻ S S Service Service Timeout! Cancel
 Exception Timeout
 Exception
73. Conclusion Lessons Learned ·ͱΊ
74. How to launch a product using Scala Lessons Learned 1. Build app from top to bottom
 to deal with product managers. 2. Manage internal state
 to deal with designers. 3. Read code
 to deal with engineers. αʔϏεΛθϩ͔Β࡞ͬͯେ੾ͩͬͨͭͷ͜ͱ
75. #thankyou @niw Questions? ͝੩ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠ɻ