New returns a configured Communicator or an error if the connection type is not supported.

Retry retries the function f until it returns a nil error, a Fatal error, or the context expires.

MockCommunicator is an implementation of Communicator that can be used for tests.

Communicator is an interface that must be implemented by all communicators used for any of the provisioners.

Fatal is an interface that error values can return to halt Retry.