FeatureFlagger

Partially release your features.

Working with Docker

Open IRB docker-compose run feature_flagger

Running tests docker-compose run feature_flagger rspec

Installation

Add this line to your application's Gemfile:

gem 'feature_flagger'

And then execute:

$ bundle

Or install it yourself as:

$ gem install feature_flagger

Configuration

By default, feature_flagger uses the REDIS_URL env var to setup it's storage. You can set up FeatureFlagger by creating a file called config/initializers/feature_flagger with the following lines:

require 'redis-namespace'
require 'feature_flagger'

FeatureFlagger.configure do |config|
  redis = Redis.new(host: ENV['REDIS_URL'])
  namespaced = Redis::Namespace.new('feature_flagger', redis: redis)
  config.storage = FeatureFlagger::Storage::Redis.new(namespaced)
end

It's also possible to configure an additional cache layer by using ActiveSupport::Cache APIs. You can configure it the same way you would setup cache_store for Rails Apps. Caching is not enabled by default.

configuration.cache_store = :memory_store, { expires_in: 100 }

Create a rollout.yml in config path and declare a rollout:

account: # model name
email_marketing: # namespace (optional)
new_email_flow: # feature key
  description:
    @dispatch team uses this rollout to introduce a new email flow for certains users. Read more at [link]

Adds rollout funcionality to your model:
```
class Account < ActiveRecord::Base
include FeatureFlagger::Model
# ....
end
```
Notifier

The notifier_callback property in config, enables the dispatch of events when a release operation happens.
```
config.notifier_callback = -> {|event| do something with event }
```

It accepts a lambda function that will receive a hash with the operation triggered like:

{
  type: 'release',
  model: 'account',
  key: 'somefeature:somerolloutkey'
  id: 'account_id' #In realease_to_all and unrelease_to_all operations id will be nil 
}

The supported operations are:

release
unrelease
release_to_all
unrelease_to_all

Usage

account = Account.first

# Release feature for account
account.release(:email_marketing, :new_email_flow)
#=> true

# Check feature for a given account
account.released?(:email_marketing, :new_email_flow)
#=> true

# In order to bypass the cache if cache_store is configured
account.released?(:email_marketing, :new_email_flow, skip_cache: true)
#=> true

# Remove feature for given account
account.unrelease(:email_marketing, :new_email_flow)
#=> true

# If you try to check an inexistent rollout key it will raise an error.
account.released?(:email_marketing, :new_email_flow)
FeatureFlagger::KeyNotFoundError: ["account", "email_marketing", "new_email_flo"]

# Check feature for a specific account id
Account.released_id?(42, :email_marketing, :new_email_flow)
#=> true

# In order to bypass the cache if cache_store is configured
Account.released_id?(42, :email_marketing, :new_email_flow, skip_cache: true)
#=> true

# Release a feature for a specific account id
Account.release_id(42, :email_marketing, :new_email_flow)
#=> true

# Get an array with all released Account ids
Account.all_released_ids_for(:email_marketing, :new_email_flow)

# Releasing a feature to all accounts
Account.release_to_all(:email_marketing, :new_email_flow)

# Unreleasing a feature to all accounts
Account.unrelease_to_all(:email_marketing, :new_email_flow)

# Return an array with all features released for all
Account.released_features_to_all

# In order to bypass the cache if cache_store is configured
Account.released_features_to_all(skip_cache: true)

Clean up action

By default when a key is removed from rollout.yml file, its data still in the storage.

To clean it up, execute or schedule the rake:

$ bundle exec rake feature_flagger:cleanup_removed_rollouts

Upgrading

When upgrading from 1.1.x to 1.2.x the following command must be executed to ensure the data stored in Redis storage is right. Check #67 and #68 for more info.

$ bundle exec rake feature_flagger:migrate_to_resource_keys

Extra options

There are a few options to store/retrieve your rollout manifest (a.k.a rollout.yml):

If you have a rollout.yml file and want to use Redis to keep a backup, add the follow code to the configuration block:

FeatureFlagger.configure do |config|
  ...
  config.manifest_source = FeatureFlagger::ManifestSources::YAMLWithBackupToStorage.new(config.storage)
  ...
end

If you already have your manifest on Redis and prefer not to keep a copy in your application, add the following code to the configuration block:

FeatureFlagger.configure do |config|
  ...
  config.manifest_source = FeatureFlagger::ManifestSources::StorageOnly.new(config.storage)
  ...
end

If you have the YAML file and don't need a backup, it is unnecessary to do any different configuration.

Contributing

Bug reports and pull requests are welcome! Please take a look at our guidelines here.