Feature Toggle Makes Development Faster and Safer @ TECHPULSE 2023

- Speaker: Euni Cheng
- Event: https://techpulse.line.me/

Feature toggle 是一種無需調整程式碼來更改系統行為的方法，幫助團隊快速且安全地向用戶提供新功能。本次將案例分享如何使用 Feature toggle 讓團隊可以在主分支上開發並且持續交付，以及介紹 Flagr 開源工具當中的架構與演算法，如果你也在關注如何提升產品體驗，歡迎前來聆聽！

Transcript

1. View Slide

2. What Is Feature Toggle
   Feature toggle is if/else controls in your code. Easily manage features without pushing a change.
   2
   A task:
   To enhance the daily lottery algorithm
   def old_daily_lottery_alg:
   # current implementation lives here
   def new_daily_lottery_alg:
   # TODO: implement better lottery alg
   Code without using feature toggle
   def daily_lottery_logic:
   # SWITCH TO TRUE IF YOU ARE WORKING ON THE NEW LOTTERY
   ALG
   use_new_alg = False
   if use_new_alg:
   new_daily_lottery_alg()
   else:
   old_daily_lottery_alg()
   Code using feature toggle
   def daily_lottery_logic:
   if feature_is_enabled("new_lottery_alg"):
   new_daily_lottery_alg()
   else:
   old_daily_lottery_alg()
   

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3. Use Case for E-commerce
   Use feature toggle to improve flexible developing schedule.
   3
   5/1
   Complete code
   5/3
   Release data
   5/5
   Release data
   5/6
   Release data
   With Feature Toggle
   5/1
   Deploy code
   API related to client A
   API related to client B
   API related to client C
   5/6
   Deploy code
   Blocked by 3rd party services
   Feature
   Release
   Code
   Deployment
   Without Feature Toggle
   API related to client A
   API related to client B
   API related to client C A B C
   A B C
   

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4. Use Case for E-commerce
   Incrementally and safely release a new feature to your users
   4
   Engineering
   Sales Product
   EC Team
   Release
   Feedback
   Feature Toggle
   FEEDBACK LOOP PERCENTAGE ROLLOUT(%)
   30%
   

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5. The Concept of Distributing Users
   Take the unique user ID, hash it using a hash function that has a uniform distribution and then mod bucket number.
   5
   Distribution
   ON OFF
   0~299
   300~999
   Algorithm
   Uid: A1234 Hashed Uid:
   2615402659
   [0, 999]
   659
   Con
   fi
   g
   Variants:
   - On
   - Off
   Segment 1(All users):
   - Constraint: None
   - Rollout Percentage: 30%
   

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6. Use Case for E-commerce
   More than on/off, we can set multi-variants, such as red, green and blue.
   6
   Result
   Segment(s)
   On
   Off
   if (variant == "on") {
   [SHOW FEATURE]
   }
   if (variant == "off") {
   [NOT SHOW FEATURE]
   }
   Your Code
   Variants
   Randomly choose 20% of users to see shopping cart.
   VIP
   Golden
   Normal
   Red
   Blue
   Green
   if (variant == "red") {
   [SHOW RED PAGE]
   }
   if (variant == "blue") {
   [SHOW BLUE PAGE]
   }
   if (variant == "green") {
   [SHOW GREEN PAGE]
   }
   Show different page color to different membership.
   

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7. 7
   Structure of a Toggle System
   Take Flagr as an example.
   

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8. Toggle CRUD Life Cycle
   Retiring toggles to avoiding technical debt!
   8
   • Development team create toggles when required.
   • Application read or expose toggled feature when they are switched ON.
   • Development team update toggled features when they are buggy.
   • A semi-automated process to destroy or remove toggles when job is done.
   Source: Feature Toggles (aka Feature Flags)
   

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9. Why FT makes development faster and safer?
   9
   Feature
   Release
   Code
   Deployment
   • Modify system behavior without changing code
   • Test a new feature without needing a separate testing environment.
   • Reduce release risk with an instant kill switch.
   

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10. Thank you
    10
    

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