1 files changed, 77 insertions, 0 deletions
diff --git a/lib/api/unleash.rb b/lib/api/unleash.rb
new file mode 100644
index 00000000000..907422118f1
--- /dev/null
+++ b/lib/api/unleash.rb
@@ -0,0 +1,77 @@
+# frozen_string_literal: true
+
+module API
+  class Unleash < ::API::Base
+    include PaginationParams
+
+    namespace :feature_flags do
+      resource :unleash, requirements: API::NAMESPACE_OR_PROJECT_REQUIREMENTS do
+        params do
+          requires :project_id, type: String, desc: 'The ID of a project'
+          optional :instance_id, type: String, desc: 'The Instance ID of Unleash Client'
+          optional :app_name, type: String, desc: 'The Application Name of Unleash Client'
+        end
+        route_param :project_id do
+          before do
+            authorize_by_unleash_instance_id!
+          end
+
+          get do
+            # not supported yet
+            status :ok
+          end
+
+          desc 'Get a list of features (deprecated, v2 client support)'
+          get 'features' do
+            present :version, 1
+            present :features, feature_flags, with: ::API::Entities::UnleashFeature
+          end
+
+          desc 'Get a list of features'
+          get 'client/features' do
+            present :version, 1
+            present :features, feature_flags, with: ::API::Entities::UnleashFeature
+          end
+
+          post 'client/register' do
+            # not supported yet
+            status :ok
+          end
+
+          post 'client/metrics' do
+            # not supported yet
+            status :ok
+          end
+        end
+      end
+    end
+
+    helpers do
+      def project
+        @project ||= find_project(params[:project_id])
+      end
+
+      def unleash_instance_id
+        env['HTTP_UNLEASH_INSTANCEID'] || params[:instance_id]
+      end
+
+      def unleash_app_name
+        env['HTTP_UNLEASH_APPNAME'] || params[:app_name]
+      end
+
+      def authorize_by_unleash_instance_id!
+        unauthorized! unless Operations::FeatureFlagsClient
+          .find_for_project_and_token(project, unleash_instance_id)
+      end
+
+      def feature_flags
+        return [] unless unleash_app_name.present?
+
+        legacy_flags = Operations::FeatureFlagScope.for_unleash_client(project, unleash_app_name)
+        new_version_flags = Operations::FeatureFlag.for_unleash_client(project, unleash_app_name)
+
+        legacy_flags + new_version_flags
+      end
+    end
+  end
+end