Allow the feature flags to be enabled/disabled with more granularity

This allows to enable/disable a feature flag for a given user, or a
given Flipper group (must be declared statically in the `flipper.rb`
initializer beforehand).

Signed-off-by: Rémy Coutable <remy@rymai.me>

2 files changed, 49 insertions, 11 deletions

diff --git a/lib/api/features.rb b/lib/api/features.rb
index cff0ba2ddff..4e10e36fce9 100644
--- a/lib/api/features.rb
+++ b/lib/api/features.rb
@@ -2,6 +2,29 @@ module API
   class Features < Grape::API
     before { authenticated_as_admin! }
 
+    helpers do
+      def gate_value(params)
+        case params[:value]
+        when 'true'
+          true
+        when '0', 'false'
+          false
+        else
+          params[:value].to_i
+        end
+      end
+
+      def gate_target(params)
+        if params[:flipper_group]
+          Feature.group(params[:flipper_group])
+        elsif params[:user]
+          User.find_by_username(params[:user])
+        else
+          gate_value(params)
+        end
+      end
+    end
+
     resource :features do
       desc 'Get a list of all features' do
         success Entities::Feature
@@ -17,16 +40,21 @@ module API
       end
       params do
         requires :value, type: String, desc: '`true` or `false` to enable/disable, an integer for percentage of time'
+        optional :flipper_group, type: String, desc: 'A Flipper group name'
+        optional :user, type: String, desc: 'A GitLab username'
       end
       post ':name' do
         feature = Feature.get(params[:name])
+        target = gate_target(params)
+        value = gate_value(params)
 
-        if %w(0 false).include?(params[:value])
-          feature.disable
-        elsif params[:value] == 'true'
-          feature.enable
+        case value
+        when true
+          feature.enable(target)
+        when false
+          feature.disable(target)
         else
-          feature.enable_percentage_of_time(params[:value].to_i)
+          feature.enable_percentage_of_time(value)
         end
 
         present feature, with: Entities::Feature, current_user: current_user
diff --git a/lib/feature.rb b/lib/feature.rb
index d3d972564af..363f66ba60e 100644
--- a/lib/feature.rb
+++ b/lib/feature.rb
@@ -12,6 +12,8 @@ class Feature
   end
 
   class << self
+    delegate :group, to: :flipper
+
     def all
       flipper.features.to_a
     end
@@ -27,16 +29,24 @@ class Feature
       all.map(&:name).include?(feature.name)
     end
 
-    def enabled?(key)
-      get(key).enabled?
+    def enabled?(key, thing = nil)
+      get(key).enabled?(thing)
+    end
+
+    def enable(key, thing = true)
+      get(key).enable(thing)
+    end
+
+    def disable(key, thing = false)
+      get(key).disable(thing)
     end
 
-    def enable(key)
-      get(key).enable
+    def enable_group(key, group)
+      get(key).enable_group(group)
     end
 
-    def disable(key)
-      get(key).disable
+    def disable_group(key, group)
+      get(key).disable_group(group)
     end
 
     def flipper