old_contents: # Licensed to the StackStorm, Inc ('StackStorm') under one or more
  # contributor license agreements.  See the NOTICE file distributed with
  # this work for additional information regarding copyright ownership.
  # The ASF licenses this file to You under the Apache License, Version 2.0
  # (the "License"); you may not use this file except in compliance with
  # the License.  You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  __all__ = [
      'BACKENDS_NAMESPACE'
  ]
  
  BACKENDS_NAMESPACE = 'st2common.runners.runner'
  
new_contents: # Licensed to the StackStorm, Inc ('StackStorm') under one or more
  # contributor license agreements.  See the NOTICE file distributed with
  # this work for additional information regarding copyright ownership.
  # The ASF licenses this file to You under the Apache License, Version 2.0
  # (the "License"); you may not use this file except in compliance with
  # the License.  You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  from stevedore.driver import DriverManager
  from stevedore.extension import ExtensionManager
  
  __all__ = [
      'BACKENDS_NAMESPACE',
  
      'get_available_backends',
      'get_backend_instance'
  ]
  
  BACKENDS_NAMESPACE = 'st2common.runners.runner'
  
  
  def get_available_backends():
      """
      Return names of the available / installed action runners.
  
      :rtype: ``list`` of ``str``
      """
      manager = ExtensionManager(namespace=BACKENDS_NAMESPACE, invoke_on_load=False)
      return manager.names()
  
  
  def get_backend_instance(name):
      """
      Return a class instance for the provided runner name.
      """
      manager = DriverManager(namespace=BACKENDS_NAMESPACE, name=name, invoke_on_load=False)
      return manager.driver
  
subject: Add functions for retrieving a list of dynamically registered runners.