Use middleware Rack::Static

lib/diversipub/rack_app.rb

@@ -21,8 +21,18 @@ module Diversipub
 
     def builder
       @builder ||= Rack::Builder.new.tap do |builder|
+        builder.use Rack::Static, **rack_static_kwargs
         builder.run @sinatra_app
       end
     end
+
+    def rack_static_kwargs
+      @rack_static_kwargs ||= {
+        cascade: true,
+        index: 'index.html',
+        root: File.expand_path('../website/build').freeze,
+        urls: [''].freeze,
+      }.freeze
+    end
   end
 end

lib/diversipub/sinatra_app.rb

@@ -20,8 +20,8 @@ module Diversipub
       alias new new!
     end
 
-    get '/' do
-      'Hello, World!'
+    get '/index.html' do
+      redirect 'ru/index.html'
     end
   end
 end