31 lines
1.6 KiB
Markdown
31 lines
1.6 KiB
Markdown
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Why use feature flags?
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======================
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* **Velocity**: coupled with a system to rapidly deploy configuration change,
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it is usually much faster to disable new code by turning off a feature than
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re-deploying all the code. This extra safety net helps developers be more
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confident in their release, because they know they can roll back a change
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very rapidly in case of error.
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* **Testing**: the presence of a feature flag forces the feature owner to test
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the flow. Without feature flags, the developer might deploy the change and
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assume the absence of errors means the release was successful. Yet there's
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numerous failure mode that don't raise explicit errors.
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* **Code iterations**: because code can be kept hidden behind a feature flag
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until it's ready to go live, developers can push smaller code changes that
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are not fully integrated yet. Smaller pull requests ease the job of code
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reviewers, make testing easier, and reduce the probability of a catastrophic
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failure.
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* **Gradual rollout**: feature flags enable gradual rollout, where a piece of
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code is gradually activated, for instance on a per city basis, or on a per
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user group basis. This builds confidence in the feature release process.
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References
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----------
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* Martin Fowler,
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[FeatureToggle](http://martinfowler.com/bliki/FeatureToggle.html)
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* Flickr, [Flipping Out](http://code.flickr.net/2009/12/02/flipping-out/): one
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of the first articles on the topic.
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* [Using Feature Flags to Ship Changes with
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Confidence](http://blog.travis-ci.com/2014-03-04-use-feature-flags-to-ship-changes-with-confidence/)
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