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s
( Rollout, feature flag, experiment, operational toggle) title
(Different use cases for backend, frontend and mobile ) authortwo
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() n
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() n
( "Feature flags" tend to come up when talking about continuous deployment) title
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() n
() n
() n
() n
(CI: continuous integration) authortwo
() n
(CD: continuous delivery) authortwo
() n
(CD: continuous deployment) authortwo
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( Types) header
() n
() n
() n
(1. rollout) n
(2. feature flag) n
(3. experiment) n
(4. operational toggle) n
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( Rollout) header
( For *rolling out* a new version of software) title
(Short-lived using percentages) n
(- a new deployment of kubernetes) n
(- new APK released to the Play Store) n
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( Feature flag) header
( For turning a feature *on* or *off* ) title
(Medium-lived using allow list, A/B test, percentage, app version, etc.) n
(- :new-chargeback-flow) n
(- :new-debit-card-activation-screen) n
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( Experiment) header
( For analysing behaviour) title
(Medium-lived using allow list and A/B test) n
(- :debit-withdrawal-test) n
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( Operational toggle) header
( For disabling features in #crash-like situations) title
(Long-lived using percentage) n
(- :bank-barcode-payment) n
(- :savings-bank-barcode-query-provider) n
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() n
() n
(We know know about the types) authortwo
( But they have different relevance for backend, frontend and mobile) title
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( backend) header
() n
() n
(1. rollout: k8s blue/green, canary and ~common-rollout~ common-xp) n
(2. feature flag: ~common-rollout~ common-xp and datasets) n
(3. experiment: common-xp) n
(4. operational toggle: ~common-rollout~ common-xp ) n
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( frontend) header
() n
() n
(1. rollout: CDN and page refreshes) n
(2. feature flag: percentages and maybe IPs \(no :customer/id on the website\)) n
(3. experiment: via dynamic backend control) n
(4. operational toggle: via dynamic backend control ) n
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( backend) header
() n
() n
(1. rollout: app stores) n
(2. feature flag: via dynamic backend control) n
(3. experiment: via dynamic backend control) n
(4. operational toggle: via dynamic backend control ) n
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() n
() n
(Key differentiator is) authortwo
( how much *control* we have over the environment) title
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( backend) header
( full control) title
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( frontend) header
( partial control) title
(We choose when to make a new version available ) n
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( mobile) header
( very limited control) title
(- app stores can restrict updates \(worse for iOS\)) n
(- customers still have to download new versions ) n
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( Costs) title
(- more complex code) n
(- compatibility with old app versions) n
(- nesting is exponential) n
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( Benefits) title
(- dynamicity) n
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( weighting costs � benefits) header
( The less control we have, the more we value dynamicity ) title
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( weighting costs � benefits) header
() n
() n
() n
(- backend: sometimes worth the cost) n
(- frontend: almost always worth the cost) n
(- mobile: *always* worth the cost) n
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() n
() n
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( Best practices) title
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( dynamic content > feature flag) title
(Always true for mobile, almost always for frontend ) n
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( Use :include-list for named groups ) title
(Always true for backend, frontend and mobile ) n
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({:rules) cn
( #{{:types :include-list) cn
( :content {:filename "debit-team-members.txt"}}}}) cn
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( Always use :app-version) title
(Only for mobile) n
bs
({:rules) cn
( #{{:types :app-version) cn
( :content {:min-version #{{:platform :android) cn
( :code 1000000}) cn
( {:platform :ios) cn
( :code 2000000}}}}}}) cn
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( Extend ~common-rollout~ common-xp if required) title
(That's how :include-list, :app-version, etc. were born) n
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( Beware of many nested feature flags) title
(True for backend, frontend and mobile) n
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( Don't delete app-facing feature flags) title
(True for mobile) n
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s
() n
() n
() n
( Include a feature flag on the whiteboarding phase) title
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() n
() n
() n
( Include deleting/retiring the feature flag at the end) title
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( Avoid renaming a feature flag) title
(Use :app-version with :min-version instead) n
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() n
() n
() n
( And most importantly...) title
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( *Always* rely on a feature flag on the app) title
(Never do a hotfix, avoid expedited releases at all costs) n
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( References) header
() n
(1. "Feature Toggles \(aka Feature Flags\)", by Pete Hodgson) n
(2. "Continuous integration vs. delivery vs. deployment", by Sten Pittet) n
(3. Accelerate, by N. Forsgren, J. Humble and G. Kim) n
(4. these slides: euandre.org/slide/) n
(5. prose version of this presentation) n
(6. view source) n
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