raise TypeError("Authentication class %s.KallitheaAuthPluginBase "

                        "has overridden the plugin_settings method, which is "

                        "forbidden." % plugin)

    return plugin

def get_auth_plugins():

    """Return a list of instances of plugins that are available and enabled"""

    auth_plugins = []

    for plugin_name in Setting.get_by_name("auth_plugins").app_settings_value:

        try:

            plugin = loadplugin(plugin_name)

            log.exception('Failed to load authentication module %s' % (plugin_name))

        else:

            auth_plugins.append(plugin)

    return auth_plugins

def authenticate(username, password, environ=None):

    """

    Authentication function used for access control,

    It tries to authenticate based on enabled authentication modules.

    :param username: username can be empty for container auth