In order to verify that the caller is running on the specified node,
we source the expected IP address from the cloud, and require that the
node set up a simple challenge/response server to answer requests.
Because the challenge server runs on a port outside of the nodePort
range, this also makes it harder for pods to impersonate their host
nodes - though we do combine this with TPM and similar functionality
where it is available.
kops-controller can now serve the instance group & cluster config to
nodes, as part of the bootstrap process.
This enables nodes to boot without access to the state
store (i.e. without S3 / GCS / etc permissions)
Feature-flagged behind the KopsControllerStateStore feature-flag.