Feature Flags & You

Given at BrooklynJS November 2017

Transcript

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3. 84 slides
   4 sections
   42 minutes
   

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5. Rule: Scale is bytes served, users concurrent
   

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6. Reality: Scale is responding to bytes served and
   users concurrent
   

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10. Reality: Scale is responding to bytes served and
    users concurrent
    

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11. How fast can you deploy a change?
    

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12. How fast can you FIX a change?
    

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13. How fast can you VALIDATE a change?
    

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15. Team 1
    Team 2
    Merge Feature A
    Merge Feature B
    Deploy
    Deploy
    OMG
    ROLLBACK
    DEPLOY!!!
    Merge Feature C
    Merge Bugfix for A
    Deploy
    Deploy BLOCKED!!!
    Deploy
    

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16. Feature Flags!
    

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19. If User has Feature:
    Show New Experience
    Else:
    Show Legacy Experience
    

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20. Feature Flags Divorce Rollout from Deployment
    

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21. Team 1
    Team 2
    Merge Feature A
    Merge Feature B
    Deploy
    Deploy
    Rollout Flag A
    Rollout Flag B
    OMG
    ROLLBACK
    FLAG
    A!!!
    Merge Feature C
    Deploy
    Merge Bugfix for A
    Deploy
    Rollout Flag A
    Rollout Flag C
    

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22. It Depends™ on your ENG and PROD teams!
    What is the scope of a Feature Flag?
    

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23. Feature Package Permission
    Implementation If/Else Gate If/Else Gate If/Else Gate
    Target Beta Cohort Client Tier Role / Org Chart
    Owner Prod / Eng Prod / Sales / CS Client
    

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24. Feature Flags are not Packages…
    Feature Flags are for new code…
    Feature Flags are temporary!
    

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25. 1.Feature is planned with PROD & ENG
    2.ENG creates flag, all new code behind flag
    3.ENG opens flag to feature devs
    4.ENG does code review, merges, deploys
    5.ENG opens flag to PROD
    6.PROD approves, begins rolling out live
    7.PROD confirms 100% successful rollout
    8.ENG & PROD schedules sprint for removal
    9.ENG removes old code & flag
    

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26. 1.At least 1 engineer codes with flag OFF
    2.All changes to existing code behind flag
    3.Rigorously QA with both flag ON and OFF
    4.Seriously, check that flag OFF still works
    5.No regressions!
    6.You will make this mistake.
    7.Did you make this mistake?
    8.Learn from it then do #1 and #3 again
    

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27. Build or Buy?
    

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28. 1.Retrieve flag by name…
    2.With current user details…
    3.And serve variations based on above…
    4.Accessible enough your PM can manage it.
    

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30. }>
    
    
    

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32. 1.Iterating faster is Good™!
    2.Optimize for inevitable rollbacks
    3.Feature flags solve for both
    4.I was wrong to hate them for so long
    

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