var SSHUser = "ubuntu"
The user name used to ssh into Juju nodes. Override for testing.
Manifold returns a dependency manifold that runs a authenticationworker worker, using the resource names defined in the supplied config.
NewWorker returns a worker that keeps track of the machine's authorised ssh keys and ensures the ~/.ssh/authorized_keys file is up to date.
ManifoldConfig defines the names of the manifolds on which a Manifold will depend.