Remove status enum from Gcp::Cluster, use state_machine#state

app/models/gcp/cluster.rb

@@ -25,13 +25,6 @@ module Gcp
       key: Gitlab::Application.secrets.db_key_base,
       algorithm: 'aes-256-cbc'
-    enum status: {
-      scheduled: 1,
-      creating: 2,
-      created: 3,
-      errored: 4
-    }
-
     validates :gcp_project_id,
       length: 1..63,
       format: {
@@ -67,6 +60,11 @@ module Gcp
     validate :restrict_modification, on: :update, unless: :status_changed?
     state_machine :status, initial: :scheduled do
+      state :scheduled, value: 1
+      state :creating, value: 2
+      state :created, value: 3
+      state :errored, value: 4
+
       event :make_creating do
         transition any - [:creating] => :creating
       end
@@ -86,7 +84,7 @@ module Gcp
       before_transition any => [:errored] do |cluster, transition|
         status_reason = transition.args.first
-        cluster.status_reason = status_reason
+        cluster.status_reason = status_reason if status_reason
       end
     end

app/serializers/cluster_entity.rb

 class ClusterEntity < Grape::Entity
   include RequestAwareEntity
-  expose :status
+  expose :status_name, as: :status
   expose :status_reason
 end

app/services/ci/create_cluster_service.rb

@@ -5,7 +5,6 @@ module Ci
       project.create_cluster(
         params.merge(user: current_user,
-                     status: Gcp::Cluster.statuses[:scheduled],
                      gcp_token: access_token)).tap do |cluster|
         ClusterProvisionWorker.perform_async(cluster.id) if cluster.persisted?
       end

app/views/projects/clusters/show.html.haml

 - status_path = status_namespace_project_cluster_path(@cluster.project.namespace, @cluster.project, @cluster.id, format: :json) if can?(current_user, :admin_cluster, @cluster) && @cluster.on_creation?
 .row.prepend-top-default.edit-cluster-form.js-edit-cluster-form{ data: { status_path: status_path,
   toggle_status: @cluster.enabled? ? 'true': 'false',
-  cluster_status: @cluster.status,
+  cluster_status: @cluster.status_name,
   cluster_status_reason: @cluster.status_reason }}
   = render 'sidebar'
   .col-lg-8

spec/factories/gcp/cluster.rb

@@ -13,11 +13,17 @@ FactoryGirl.define do
     end
     trait :created_on_gke do
+      status_event :make_created
       endpoint '111.111.111.111'
       ca_cert 'xxxxxx'
       kubernetes_token 'xxxxxx'
       username 'xxxxxx'
       password 'xxxxxx'
     end
+
+    trait :errored do
+      status_event :make_errored
+      status_reason 'general error'
+    end
   end
 end