application.rb

# config/application.rb
# Add Warden in the middleware stack
config.middleware.insert_after ActionDispatch::Flash, Warden::Manager do |manager|
  manager.default_strategies :authentication_token
end

warden.rb

#config/initializers/warden.rb
require Rails.root.join('lib/strategies/authentication_token_strategy')

Warden::Strategies.add(:authentication_token, AuthenticationTokenStrategy)