"""Transport factory."""
import importlib
from cumin import CuminError
[docs]class Transport:
"""Transport factory class.
The transport layer is the one used to convey the commands to be executed into the selected hosts. The transport
abstraction allow to specify a mode to choose the execution plan, an event handler class and a success threshold.
Those can be used by the chosen transport to customize the behavior of the execution plan.
All the transports share a common interface that is defined in the :py:class:`cumin.transports.BaseWorker` class
and they are instantiated through the :py:class:`cumin.transport.Transport` factory class. Each transport module
need to define a ``worker_class`` module variable that is a pointer to the transport class for dynamic
instantiation.
"""
[docs] @staticmethod
def new(config, target):
"""Create a transport worker class based on the configuration (`factory`).
Arguments:
config (dict): the configuration dictionary.
target (cumin.transports.Target): a Target instance.
Returns:
BaseWorker: the created worker instance for the configured transport.
Raises:
cumin.CuminError: if the configuration is missing the required ``transport`` key.
exceptions.ImportError: if unable to import the transport module.
exceptions.AttributeError: if the transport module is missing the required ``worker_class`` attribute.
"""
if 'transport' not in config:
raise CuminError("Missing required parameter 'transport' in the configuration dictionary")
try:
module = importlib.import_module('cumin.transports.{transport}'.format(transport=config['transport']))
return module.worker_class(config, target)
except (AttributeError, ImportError) as e:
raise CuminError("Unable to load worker class for transport '{transport}': {msg}".format(
transport=config['transport'], msg=repr(e))) from e