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).
This method has been unused by k8s for some time, and yet is the last
piece of the cloud provider API that encourages provider names to be
human-friendly strings (this method applies a regex to instance names).
Actually removing this deprecated method is part of a long effort to
migrate from instance names to instance IDs in at least the OpenStack
provider plugin.
We had another bug where we confused the hostname with the NodeName.
To avoid this happening again, and to make the code more
self-documenting, we use types.NodeName (a typedef alias for string)
whenever we are referring to the Node.Name.
A tedious but mechanical commit therefore, to change all uses of the
node name to use types.NodeName
Also clean up some of the (many) places where the NodeName is referred
to as a hostname (not true on AWS), or an instanceID (not true on GCE),
etc.
