Feature Flags

Description

CartoDB has a built-in mechanism for feature toggling that you can use to enable/disable in a user basis, which is useful for development. Some inspirational links:

• http://martinfowler.com/bliki/FeatureToggle.html
• http://techblog.outbrain.com/tag/feature-flags/
• http://code.flickr.net/2009/12/02/flipping-out/
• http://stackoverflow.com/questions/7707383/what-is-a-feature-flag
• http://www.swig.org/Doc1.3/Customization.html#Customization_feature_flags

Usage example

• Normal usage:

  • JS: user.data returns an object with a new property called feature_flags that is an array of feature flags names. Example:

  <%=raw current_user.data.to_json.html_safe %>
  

  outputs

  {"id":"fca9 (...), "feature_flags":['ghost_tables']}
  

  • JS: the user's function featureEnabled(name) (ref. source code) returns true if the user has the flag passed by parameter enabled; else, it returns false.

  • Ruby backend: user.has_feature_flag?('new_dashboard') (nil safe).

• Model

  • user.feature_flags: feature flag names array.
  • user.feature_flags_user: Rails collection of FeatureFlagsUser (but you should not use directly, use the previous array).

Configuration

Developers can benefit from configuration just by adding feature flags to the table feature_flags and activating it to specific users though feature_flag_users. And remember you can make feature flags available for everybody just by setting restricted to f.

Example for Rails console:

Enter Rails console at CartoDB root with bundle exec rails c.

• Add new feature flag:

1.9.3-p551 :011 >   ff = FeatureFlag.new(name: 'my_feature_flag_101', restricted: true)
 => #<FeatureFlag @values={:name=>"my_feature_flag_101", :restricted=>true}>
1.9.3-p551 :012 > ff.id = 101
 => 101
1.9.3-p551 :013 > ff.save
 => #<FeatureFlag @values={:id=>101, :name=>"my_feature_flag_101", :restricted=>true, :created_at=>2014-12-11 12:49:13 +0000, :updated_at=>2014-12-11 12:49:13 +0000}>

• Assign the new feature flag to a user:

1.9.3-p551 :014 > user = User.all.first
 => #<User @values={:email=>"[email protected]", ...
1.9.3-p551 :016 > ffu = FeatureFlagsUser.new(feature_flag_id: ff.id, user_id: user.id)
 => #<FeatureFlagsUser @values={:feature_flag_id=>101, :user_id=>"2e1dc763-4501-426d-8a1d-ea8c6195ece1"}>
1.9.3-p551 :017 > ffu.save
 => #<FeatureFlagsUser @values={:id=>16, :feature_flag_id=>101, :user_id=>"2e1dc763-4501-426d-8a1d-ea8c6195ece1", :created_at=>2014-12-11 12:51:14 +0000, :updated_at=>2014-12-11 12:51:14 +0000}>

SQL example:

Connect to your local PostgreSQL with psql -U postgres -d carto_db_development.

insert into feature_flags (id, name, restricted) values (666, 'hell_of_feature', true);
insert into feature_flags_users (feature_flag_id, user_id) values (666, 'd73806fd-cc7e-41bb-9fd8-d0d8d1579196');