Enable basic auth if a username and password are set.
user
```ruby
if ENV.key?("APP_USERNAME") && ENV.key?("APP_PASSWORD")
  Vowessly::Application.config.middleware.insert_after 'Rack::Lock', 'Rack::Auth::Basic' do |username, password|
    username == ENV["APP_USERNAME"] && password == ENV["APP_PASSWORD"]
  end
end
```
assistant