Schedule k8s application installation with a service

app/controllers/projects/clusters/applications_controller.rb

@@ -5,12 +5,12 @@ class Projects::Clusters::ApplicationsController < Projects::ApplicationControll
   before_action :authorize_create_cluster!, only: [:create]
 
   def create
-    return render_404 if application
-
     respond_to do |format|
       format.json do
-        # TODO: Do that via Service
-        if application_class.create(cluster: cluster).persisted?
+        scheduled = Clusters::Applications::ScheduleInstallationService.new(project, current_user,
+                                                                            application_class: @application_class,
+                                                                            cluster: @cluster).execute
+        if scheduled
           head :no_data
         else
           head :bad_request
@@ -26,10 +26,6 @@ class Projects::Clusters::ApplicationsController < Projects::ApplicationControll
   end
 
   def application_class
-    Clusters::Cluster::APPLICATIONS[params[:application]] || render_404
-  end
-
-  def application
-    application_class.find_by(cluster: cluster)
+    @application_class ||= Clusters::Cluster::APPLICATIONS[params[:application]] || render_404
   end
 end

app/models/clusters/applications/helm.rb

@@ -11,6 +11,8 @@ module Clusters
 
       default_value_for :version, Gitlab::Kubernetes::Helm::HELM_VERSION
 
+      validates :cluster, presence: true
+
       def name
         NAME
       end

app/models/clusters/concerns/application_status.rb

@@ -23,6 +23,14 @@ module Clusters
             transition any - [:errored] => :errored
           end
 
+          event :make_scheduled do
+            transition %i(installable errored) => :scheduled
+          end
+
+          before_transition any => [:scheduled] do |app_status, _|
+            app_status.status_reason = nil
+          end
+
           before_transition any => [:errored] do |app_status, transition|
             status_reason = transition.args.first
             app_status.status_reason = status_reason if status_reason

app/services/clusters/applications/schedule_installation_service.rb

@@ -0,0 +1,27 @@
+module Clusters
+  module Applications
+    class ScheduleInstallationService < ::BaseService
+      def execute
+        application = application_class.find_or_create_by!(cluster: cluster)
+
+        application.make_scheduled!
+        ClusterInstallAppWorker.perform_async(application.name, application.id)
+        true
+      rescue ActiveRecord::RecordInvalid
+        false
+      rescue StateMachines::InvalidTransition
+        false
+      end
+
+      private
+
+      def application_class
+        params[:application_class]
+      end
+
+      def cluster
+        params[:cluster]
+      end
+    end
+  end
+end