FeatureGuard

Lightweight Redis-based feature-flagging for Ruby apps. Provides a simple syntax for enabling and disabling features, or gradually ramping up and down by enabling features for a percentage of total traffic.

Installation

Add this line to your application's Gemfile:

gem 'feature_guard'

And then execute:

$ bundle

Or install it yourself as:

$ gem install feature_guard

Usage

Check whether a feature is enabled globally:

FeatureGuard.enabled? :my_feature

Globally enable or disable a feature:

FeatureGuard.enable  :my_feature
FeatureGuard.disable :my_feature
FeatureGuard.toggle  :my_feature

Feature names can be strings or symbols. No data setup is necessary; any check for a feature which has never been enabled simply returns false.

For more fine-grained control, set a ramp-up value to decide which percentage of traffic should see the feature:

FeatureGuard.set_ramp  :my_feature, 30.5  # 30.5%
FeatureGuard.bump_ramp :my_feature, 12    # 30.5 + 12 = 42.5%
FeatureGuard.bump_ramp :my_feature        # 42.5 + 10 = 52.5%

FeatureGuard.ramp_val :my_feature # 52.5

.set_ramp sets the ramp-up value; .bump_ramp increments or decrements it by a given value (defaults to 10.0). Check the current ramp-up value with .ramp_val.

Check whether to show the feature at the current ramp-up value:

FeatureGuard.allow? :my_feature, user_id
# true for 52.5% of user_id values

FeatureGuard.allow? :my_feature
# true for 52.5% of checks (random)

The optional second argument to.allow? can be of any type (e.g., user ID or name or even an object). It is hashed with the feature name to create a reproducible numeric value for checking whether to return true or false based on the current ramp-up value. With no second argument, .allow? uses a new random value on every call.

To retrieve information on all binary-enabled/disabled features, use .all_flags:

FeatureGuard.enable :my_feature
FeatureGuard.enable :another_feature
FeatureGuard.toggle :my_feature
FeatureGuard.all_flags
# {"my_feature"=>false, "another_feature"=>true}

To retrieve information on all ramp values, use .all_ramps:

FeatureGuard.set_ramp :my_feature, 50
FeatureGuard.set_ramp :another_feature, 30
FeatureGuard.all_ramps
# {"my_feature"=>50.0, "another_feature"=>30.0}

Configuration

Optionally change the Redis client with:

FeatureGuard.redis = my_redis_client

Setting FeatureGuard.redis to nil will revert it to a new default instance (Redis.new).

Running tests

$ bundle exec rspec

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request