Snippet of code to manually connect Devise without going to warden strategies.

session_controller.rb

def create
  resource = User.find_for_database_authentication(email: params[:user][:email])
  return invalid_login_attempt unless resource

  if resource.valid_password?(params[:user][:password])
    sign_in :user, resource
    return render nothing: true
  end

  invalid_login_attempt
end