Tackling Android at Scale

In this talk I presented our journey at N26 during from early 2018 until mid 2019, where we went from 5 to 27 developers and how we achieved technical readiness that supported that growth!

Transcript

1. android.scale() @fabiocarballo
2. “Building a bank the world loves to use.
3. Hypergrowth mode
5. 2014 5 Number of Android devs
6. 2016 5 Number of Android devs
7. 2016 5 Number of Android devs
8. 2017 5 Number of Android devs
9. 5 2018 15 Number of Android devs
10. 27 15 5 Now Number of Android devs
11. 500% 1.5 years
12. Technical Readiness Scale Recruiting Onboarding Automation Releases Team Culture
13. How do we approach code?
14. Broken Windows
16. What to consider defining your architecture?
17. What to consider defining your architecture? -Reduce number of discussions -Embrace evolution -Favour testability -Protects from making mistakes
18. Architecture
19. Activity Reactive Dependency Injection Layered Architecture core:
20. Reactive
21. Receive 10 € into Main Account Reactive
22. S1 S1 S2 S3 S1 spaces reactive store Receive 10 € into Main Account spaces microservice GET /spaces Reactive Space Details View Model
23. spaces reactive store spaces microservice GET /spaces Reactive Receive 10 € into Main Account Space Details View Model
24. S1 S2 S3 Spaces Dashboard View Model Space Details View Model spaces reactive store spaces microservice GET /spaces Reactive Receive 10 € into Main Account
25. S1 S2 S3 S2 S3 S1 S2 S3 S1 S2 S3 Space Details View Model spaces reactive store spaces microservice GET /spaces Reactive Receive 10 € into Main Account Spaces Dashboard View Model
26. Feature Layered Architecture
27. Domain Feature Presentation Data
28. Domain Presentation Data Dependency Injection
29. Domain Presentation Data Dependency Injection
30. Domain Presentation Data Dependency Injection Dagger Glue
31. Be ruthless about it Defining your tech stack
32. -Which problem is it solving? Defining your tech stack
33. -Which problem is it solving? -What is the impact? Defining your tech stack
34. -Which problem is it solving? -What is the impact? -Is it actively maintained? Defining your tech stack
35. -Which problem is it solving? -What is the impact? -Is it actively maintained? 2.0.1 2.0.2 2.1.0 2.2.0 2.3.0 2.4.0 2.5.0 Retrofit Version along 2.5 years Defining your tech stack
36. Wrapping 3rd parties behind an interface is actually good.
37. Wrapping 3rd parties behind an interface is actually good.
38. app Camera Lib 1 - Keeping two Camera libs in the app Wrapping 3rd parties behind an interface is actually good.
39. app Camera Lib 1 - Keeping two Camera libs in the app Wrapping 3rd parties behind an interface is actually good.
40. app Camera Interface Camera Lib 1 - Keeping two Camera libs in the app Wrapping 3rd parties behind an interface is actually good.
41. - Keeping two Camera libs in the app app Camera Interface Camera Lib 2 Camera Lib 1 Wrapping 3rd parties behind an interface is actually good.
42. app Camera Interface Camera Lib 2 Camera Lib 1 Compression issues! camera_lib: “camera_lib_2” camera_lib: “camera_lib_2” “camera_lib_1”
43. app Camera Interface Camera Lib 2 Camera Lib 1 Compression issues! camera_lib: “camera_lib_2” “camera_lib_1”
44. Workflow Fabio Lucia
45. Fábio Lucia Workflow
46. Fábio Lucia Mustafa Omkar Ilke Sergio
47. Fábio Lucia Streams of work for 20+ persons a.k.a. Possibly many merge conflicts
48. Fábio Lucia Branch out and branch in small chunks Feature Flags
49. Commit Messages new transaction details NewTransactionsList WIP Linked- Authorising transactions dialog
50. android-machete git:(DES-156-discreet) android-machete git:(develop) git add . git checkout -b DES-156-discreet Switched to a new branch `DES-156-discreet` android-machete git:(DES-156-discreet) git commit -m “add discreet section to glossary” | JIRA ticket 'DES-156' prepended to commit message [DES-156-discreet 6219e9cbd4] DES-156 add discreet section to glossary
53. Modularisation for independence
54. app
55. Oct 14 Jan 2016 Jan 2017 Jan 2018
56. app
57. User app Login
58. app User Login Security
59. app Certification Security User Login Credit
60. app Credit Security User Login Certification
61. app Credit Security User Login Certification
62. app Certification Security User Login Credit Hidden coupling
63. app User Login Certification Security Credit Hidden coupling
64. app User Login Certification Security Credit
65. app User Login Certification Security Credit
66. Transactions
67. :transactions domain :transactions presentation :transactions data
68. :transactions domain :transactions presentation :app :transactions data
69. :spaces data :spaces domain :spaces presentation :moneyBeam data :moneyBeam domain :moneyBeam presentation :transactions presentation :app :transactions domain :transactions data
70. Jan 2019 100 modules Oct 14 Jan 2016 Jan 2017 Jan 2018
71. :transactions data :transactions domain :transactions presentation :app :spaces data :spaces domain :spaces presentation :moneyBeam data :moneyBeam domain :moneyBeam presentation
72. :transactions :app :spaces :moneyBeam
73. :transactions :app :spaces :moneyBeam moneyBeam microservice transactions microservice spaces microservice
74. :transactions :app :spaces :moneyBeam Backend for Frontend service moneyBeam microservice transactions microservice spaces microservice
75. 100 modules Jan 2019 Oct 14 Jan 2016 Jan 2017 Jan 2018
76. What about … build times? They are interesting
77. Jan 2019 Oct 14 Jan 2016 Jan 2017 Jan 2018 7m 5m 3m 1.5m Clean Build Times
78. 40% of reduction in build times Jan 2019 Oct 14 Jan 2016 Jan 2017 Jan 2018 7m 5m 3m 1.5m Clean Build Times
79. Feature Launcher Apps
80. Credit
81. Credit N26 App
82. N26 App Credit Spaces Overdraft Premium Moneybeam Transactions
83. N26 App Credit Spaces Overdraft Premium MoneyBeam Transactions 1-5mins build time
84. Launcher app Credit N26 App Spaces Overdraft Premium MoneyBeam Transactions 1-5mins build time
85. Go bottom-top, not top-bottom
86. :app
87. AppComponent NetworkModule ApplicationModule SpacesComponent SpacesModule UserComponent User Module Session Module Credit Component CreditModule :app
88. :spaces :credit SpacesComponent SpacesModule Credit Component CreditModule AppComponent NetworkModule ApplicationModule UserComponent User Module Session Module :app
89. :spaces :credit SpacesComponent SpacesModule Credit Component CreditModule AppComponent NetworkModule ApplicationModule UserComponent User Module Session Module :app Where is App/User component??????
90. :spaces :credit :base BaseComponent NetworkModule ApplicationModule Session Module SpacesComponent SpacesModule Credit Component CreditModule :app
91. Why modularize for scale? Independent teams
92. Refactor with more safety Independent teams Why modularize for scale?
93. Independent teams Refactor with more safety Creativity and Innovation Why modularize for scale?
94. Testing to release with trust
95. Oct 14 Jan 2016 Jan 2017
96. Unit Tests Oct 14 Jan 2016 Jan 2017 Easy Safe Refactoring Let you sleep
97. Unit Tests Oct 14 Jan 2016 Jan 2017 Jan 2018 Jan 2019 8000 Unit tests Easy Safe Refactoring Let you sleep
98. Easy Safe Refactoring Let you sleep Unit Tests Oct 14 Jan 2016 Jan 2017 Jan 2018 Jan 2019 8000 Unit tests
99. Oct 14 Jan 2016 Jan 2017 Jan 2018 Jan 2019 8000 Unit tests Unit Tests
100. Unit Tests Oct 14 Jan 2016 Jan 2017 Jan 2018 Jan 2019 8000 Unit tests
101. Unit Tests Oct 14 Jan 2016 Jan 2017 Jan 2018 Jan 2019 8000 Unit tests
102. Unit Tests Oct 14 Jan 2016 Jan 2017 Jan 2018 Jan 2019 8000 Unit tests
103. Unit Tests Functional UI Tests 400 UI Tests Oct 14 Jan 2016 Jan 2017 Jan 2018 Jan 2019 8000 Unit tests
104. Automated Regression 10% 50% Functional UI Tests 400 UI Tests Unit Tests Oct 14 Jan 2016 Jan 2017 Jan 2018 Jan 2019 8000 Unit tests
105. UI Testing Pipeline Slow Most difficult to fix
106. ui-pipeline.sh
107. SpacesViewModel + spaceName.text = “Space” - spaceName.text = space.name ui-pipeline.sh
108. :app :spaces :c :b :a ui-pipeline.sh SpacesViewModel + spaceName.text = “Space” - spaceName.text = space.name
109. :spaces ./run-instrumentation spaces :app :spaces :c :b :a ui-pipeline.sh SpacesViewModel + spaceName.text = “Space” - spaceName.text = space.name
110. 30+ minutes UI Testing Pipeline
111. 3 min (worst case run) UI Testing Pipeline
112. Build a Design System and bring consistency alongside
113. 80 Designers & Engineers 15 Designers & Engineers
115. That one “divider grey” Yeah it should be the grey we used in that other screen :) Is this the right grey for the divider? I thought it was this one? Hmm, I was using this to be honest
117. System Glossary
125. listOf(
126. SectionHeader("Transactions"), listOf(
127. SectionHeader("Transactions"), listOf( SubSectionHeader(“Today"),
128. TransactionContainer( "From Main Account", " to Home", Money(BigDecimal(5), Euro)), TransactionContainer( "From Main Account", "Last one ... ", Money(BigDecimal(4.50), Euro)), TransactionContainer( "From Main Account", "Just one more ", Money(BigDecimal(5), Euro)), TransactionContainer( "From Main Account", "Money for drinks!", Money(BigDecimal(5), Euro)))) SectionHeader("Transactions"), listOf( SubSectionHeader(“Today"),
129. Consistency Speed
130. Discreet Mode
131. Discreet Mode
132. Discreet Mode In a company of 1000+ people, 2 persons were able to develop and drive the launch of this feature QA Design Marketing Product Bank Security
133. QA Design Marketing Product Bank Security Discreet Mode In a company of 1000+ people, 2 persons were able to develop and drive the launch of this feature
134. Discreet Mode In a company of 1000+ people, 2 persons were able to develop and drive the launch of this feature QA Design Marketing Product Bank Security
136. Questions? n26.com/careers Berlin Barcelona New York Vienna Follow me: @fabiocarballo