Lazily sets UUID in ApplicationSetting for new installations

app/models/application_setting.rb

@@ -28,6 +28,8 @@ class ApplicationSetting < ActiveRecord::Base
 
   attr_accessor :domain_whitelist_raw, :domain_blacklist_raw
 
+  validates :uuid, presence: true
+
   validates :session_expire_delay,
             presence: true,
             numericality: { only_integer: true, greater_than_or_equal_to: 0 }
@@ -159,6 +161,7 @@ class ApplicationSetting < ActiveRecord::Base
     end
   end
 
+  before_validation :ensure_uuid!
   before_save :ensure_runners_registration_token
   before_save :ensure_health_check_access_token
 
@@ -344,6 +347,12 @@ class ApplicationSetting < ActiveRecord::Base
 
   private
 
+  def ensure_uuid!
+    return if uuid?
+
+    self.uuid = SecureRandom.uuid
+  end
+
   def check_repository_storages
     invalid = repository_storages - Gitlab.config.repositories.storages.keys
     errors.add(:repository_storages, "can't include: #{invalid.join(", ")}") unless

spec/models/application_setting_spec.rb

@@ -4,6 +4,7 @@ describe ApplicationSetting, models: true do
   let(:setting) { ApplicationSetting.create_from_defaults }
 
   it { expect(setting).to be_valid }
+  it { expect(setting.uuid).to be_present }
 
   describe 'validations' do
     let(:http)  { 'http://example.com' }