Add uuid to ApplicationSetting

db/migrate/20170328010804_add_uuid_to_application_settings.rb

+class AddUuidToApplicationSettings < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_column :application_settings, :uuid, :string
+    add_concurrent_index :application_settings, :uuid
+    execute("UPDATE application_settings SET uuid = #{quote(generate_random_string(40))}")
+  end
+
+  def down
+    remove_index :application_settings, :uuid if index_exists?(:application_settings, :uuid)
+    remove_column :application_settings, :uuid
+  end
+
+  private
+
+  def generate_random_string(size)
+    # urlsafe_base64 may return a string of size * 4/3
+    SecureRandom.urlsafe_base64(size)[0, size]
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20170317203554) do
+ActiveRecord::Schema.define(version: 20170328010804) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -129,8 +129,11 @@ ActiveRecord::Schema.define(version: 20170317203554) do
     t.string "elasticsearch_aws_access_key"
     t.string "elasticsearch_aws_secret_access_key"
     t.integer "geo_status_timeout", default: 10
+    t.string "uuid"
   end
 
+  add_index "application_settings", ["uuid"], name: "index_application_settings_on_uuid", using: :btree
+
   create_table "approvals", force: :cascade do |t|
     t.integer "merge_request_id", null: false
     t.integer "user_id", null: false