can-do

CanDo

Flips your features based on a redis key, a config/features.yml file or environment variables.

Usage

Add can-do to your Gemfile:

# Gemfile

gem "can-do", require: "can_do"

Redis values

To use redis as a storage set the environment variable CANDO_REDIS_URL with your redis instance.

The keys have to be prefixed with 'features:'.

So to set and use the feature experiment-1 set the key like

$ redis-cli SET features:experiment_1 true

and use it like

require "can_do"

CanDo.feature?(:experiment_1)

Any unset key will fall back to either the environment variable or the yaml variable and false if none is set.

require "can_do"

CanDo.feature?(:experiment_1)

Yaml File

Inside the config folder relative to your working directory create a file called features.yml. Within this file, place your default feature flags within the defaults key. All available features should be listed here, together with their default values. Add environment-specific feature flags under the environment name.

# config/features.yml

defaults:
  some_feature: false
  other_feature: true
development:
  some_feature: true
production:
  other_feature: false

Check if a feature is enabled by calling CanDo.feature?(:some_feature):

require "can_do"

CanDo.feature?(:some_feature)

Or by using a block:

require "can_do"

CanDo.feature?(:some_feature) do
  # This block is only evaluated if some_feature is enabled
end

If a feature is not found, false is returned.

Environment variables

You can use environment variables to flip your features. Environment variables always take precedence over anything within your config/features.yml file.

> RAILS_ENV=development rails console
CanDo.feature?(:some_feature) => false

> SOME_FEATURE=true RAILS_ENV=development rails console
CanDo.feature?(:some_feature) => true

> SOME_FEATURE=true RAILS_ENV=development rails console
CanDo.feature?(:some_feature) => true

> OTHER_FEATURE=true RAILS_ENV=production rails console
CanDo.feature?(:other_feature) => true

Contributing

• Fork it ( https://github.com/blacklane/can-do/fork )
• Create your feature branch (git checkout -b my-new-feature)
• Commit your changes (git commit -am 'Add some feature')
• Push to the branch (git push origin my-new-feature)
• Create a new Pull Request