Use ProviderID to address nodes in the cloudprovider
Use ProviderID to address nodes in the cloudprovider

The cloudprovider is being refactored out of kubernetes core. This is being
done by moving all the cloud-specific calls from kube-apiserver, kubelet and
kube-controller-manager into a separately maintained binary(by vendors) called
cloud-controller-manager. The Kubelet relies on the cloudprovider to detect information
about the node that it is running on. Some of the cloudproviders worked by
querying local information to obtain this information. In the new world of things,
local information cannot be relied on, since cloud-controller-manager will not
run on every node. Only one active instance of it will be run in the cluster.

Today, all calls to the cloudprovider are based on the nodename. Nodenames are
unqiue within the kubernetes cluster, but generally not unique within the cloud.
This model of addressing nodes by nodename will not work in the future because
local services cannot be queried to uniquely identify a node in the cloud. Therefore,
I propose that we perform all cloudprovider calls based on ProviderID. This ID is
a unique identifier for identifying a node on an external database (such as
the instanceID in aws cloud).

kubernetes/cloud-provider-openstack,kubernetes/cloud-provider-openstack,kubernetes/cloud-provider-openstack