Feature Flags

Feature flags are ways to control the full lifecycle of your features. They allow you to manage components and minimize risk. You can do pretty cool things like roll out features to certain users, exclude groups from seeing a feature, A/B test, and much more. Basically, deploy when you want, release when you’re ready.

Transcript

1. Feature Flags
   Brad Broulik & Nick Marsh
   

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2. Feature
   Flag!
   https://me.me/i/do-not-push-button-temptation-do-you-really-want-to-15422537
   

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3. Agenda
   •What’s a feature flag
   •Why feature flags
   •Use cases
   •Demo
   •Feature flags at HealthPartners
   •Disadvantages
   

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4. What’s a Feature Flag?
   Use cases:
   •Turn features on/off (beta test)
   •Dark launch features (beta test with specific users)
   •Canary release
   •Incremental release
   •A/B test features
   •Change behavior of a feature at runtime
   Feature flags help manage the lifecycle of your features at
   runtime with the flip of a switch.
   

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5. Why Feature Flags?
   •Reduce risk
   •Continuous Delivery or Continuous Deployment
   •A/B testing
   •Calendar or time sensitive launches
   •Deploy when you want, release when you’re ready
   

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6. Use Cases
   

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7. Disable plan for me
   Enable my prescriptions
   Enable/Disable Features at Runtime
   Off
   On
   Deploy when you want, release when you’re ready
   

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8. Feature Flag Code
   Feature
   Check
   True
   False
   Off On
   

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9. Canary Release (dark launch)
   Canary release is a technique to reduce the risk of introducing a new
   software version in production by slowly rolling out the change to a
   small subset of users before rolling it out to the entire infrastructure
   and making it available to everybody.
   Feature Feature Flag Target audience
   Off
   On
   Off
   

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10. Incremental Rollouts (dark launch)
    Feature
    80%
    40%
    10%
    100%
    Monitor
    performance, errors,
    usage metrics, rollback is
    simple, throttle rollout
    in real time
    

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11. Feature
    6-10 AM
    Calendar-driven Launches
    8:00 AM
    6:00 AM
    10:00 AM
    12:00 PM
    4:00 AM
    2:00 PM
    Time sensitive
    release (sale, promotion,
    experiment)
    

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12. Feature flags can present
    alternative user experiences for
    A/B testing exercises. For
    example, we could apply
    alternative workflows, icons, or
    content for a feature.
    A/B Testing
    A
    B
    

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13. Avoid Feature Branching
    Master
    Fork Feature branch #1
    Merge
    Release
    Feature branch #2
    Release
    Conflict
    Master
    Release Release
    Flickr doesn’t use feature branches and releases to
    production several times a day
    

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14. Feature Flag Management
    Open Source Commercial
    FF4J LaunchDarkly
    Togglz Split
    Flip
    Custom (properties,
    database)
    

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16. Feature Flags at HealthPartners
    Find Care
    Team Emerge Team
    Mobile Team Others?
    

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17. HealthPartners
    OAuth 2.0
    HealthPartners
    OAuth 1.0
    We were able to
    reduce risk by releasing
    OAuth 1.0 & 2.0 side-by-
    side and test 2.0 in isolation
    by whitelisting a few
    select testers
    Canary Release Fitbit Upgrade
    HealthPartners
    Use case
    

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18. Load balancer
    Blue Green
    Off On
    HealthPartners
    Use case
    Blue/Green Deployments
    

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19. Disadvantages
    •A feature flag becomes instant tech debt
    •Feature flag management can be complicated - knowing
    what a flag does and who owns it
    •Testing feature flags requires additional test scenarios
    •Triaging defects must take the state of the feature flag into
    consideration
    •Knight Capital went bankrupt in 45 minutes for misusing a
    feature flag and lost 460 million dollars
    

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20. Alternative Solutions
    •Manage features via a content management system - turn
    features on/off at the front door (buttons and links)
    •Manage features via fast continuous delivery pipeline
    releases
    

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21. Summary
    Use cases:
    •Turn features on/off (beta test)
    •Dark launch features (beta test with specific users):
    •Canary release
    •Incremental release
    •A/B test features
    •Change behavior of a feature at runtime
    •Deploy when you want, release when you’re ready
    Feature flags help manage the lifecycle of your features at
    runtime with the flip of a switch.
    

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22. https://funixx.wordpress.com/2012/07/19/do-not-push-button/
    Questions
    

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