add feature flag for users search

app/controllers/search_controller.rb

@@ -56,6 +56,8 @@ class SearchController < ApplicationController
   end
 
   def eager_load_user_status
+    return if Feature.disabled?(:users_search, default_enabled: true)
+
     @search_objects = @search_objects.eager_load(:status) # rubocop:disable CodeReuse/ActiveRecord
   end
 

app/helpers/search_helper.rb

@@ -203,6 +203,8 @@ module SearchHelper
   end
 
   def search_tabs?(tab)
+    return false if Feature.disabled?(:users_search, default_enabled: true)
+
     if @project
       project_search_tabs?(:members)
     else

app/services/search/global_service.rb

@@ -23,7 +23,8 @@ module Search
 
     def allowed_scopes
       strong_memoize(:allowed_scopes) do
-        %w[issues merge_requests milestones users]
+        allowed_scopes = %w[issues merge_requests milestones]
+        allowed_scopes << 'users' if Feature.enabled?(:users_search, default_enabled: true)
       end
     end
 

app/services/search/project_service.rb

@@ -16,7 +16,12 @@ module Search
     end
 
     def scope
-      @scope ||= %w[notes issues merge_requests milestones wiki_blobs commits users].delete(params[:scope]) { 'blobs' }
+      @scope ||= begin
+        allowed_scopes = %w[notes issues merge_requests milestones wiki_blobs commits]
+        allowed_scopes << 'users' if Feature.enabled?(:users_search, default_enabled: true)
+
+        allowed_scopes.delete(params[:scope]) { 'blobs' }
+      end
     end
   end
 end

lib/api/search.rb

@@ -54,7 +54,14 @@ module API
       end
 
       params :scope do |options|
-        values = SCOPE_ENTITY.stringify_keys.slice(*options[:values]).keys
+        scope_entities =
+          if Feature.enabled?(:users_search, default_enabled: true)
+            SCOPE_ENTITY
+          else
+            SCOPE_ENTITY.reject { |key, value| key == :users }
+          end
+
+        values = scope_entities.stringify_keys.slice(*options[:values]).keys
 
         requires :scope,
           type: String,