= bootstrap_form_for(resource, :as => resource_name, :url => session_path(resource_name)) do |f|
  .form-group
    = f.email_field :email
  .form-group
    = f.password_field :password
    - if devise_mapping.recoverable? && controller_name != 'passwords'
      = link_to "Forgot your password?", new_password_path(resource_name)
      %br/
  - if devise_mapping.rememberable?
    .form-group
      = f.check_box :remember_me
  %div
    = f.submit "Sign in"

= bootstrap_form_for(resource, :as => resource_name, :url => session_path(resource_name)) do |f|
  .form-group
    = f.email_field :email, :required => true
  .form-group
    = f.password_field :password, :required => true
    - if devise_mapping.recoverable? && controller_name != 'passwords'
      = link_to "Forgot your password?", new_password_path(resource_name)
      %br/
  - if devise_mapping.rememberable?
    .form-group
      = f.check_box :remember_me
  %div
    = f.submit "Sign in"

Add required attributes to email/password on login form.
Add required attributes to email/password on login form.
