gitlab-org--gitlab-foss/config/initializers/7_omniauth.rb

module OmniAuth::Strategies
  server = Gitlab.config.ldap.servers.values.first
  const_set(server['provider_class'], Class.new(LDAP))
end

OmniauthCallbacksController.class_eval do
  server = Gitlab.config.ldap.servers.values.first
  alias_method server['provider_name'], :ldap
end