As of k8s 1.16, the node-role label is protected for security reasons.
We will introduce a controller to set those labels generically.
However, we need these labels to run the controller (only) on master
nodes.
To solve this bootstrapping problem, we use protokube to apply the
master role node labels to the master node only. This isn't a
security problem because we assume that protokube on the master is
highly trusted - we are still administering labels centrally.
Then kops-controller can use this label to target the master nodes,
and run a central label controller.
We don't call klog.InitFlags yet, because that will cause a flag
redefinition error until we get everyone to stop using glog. That
will happen when we update to k8s 1.13.
Otherwise we end up with a circular dependency where we don't run the
node-authorizer until /var/lib/kubelet has been bind-mounted, but it
can't be bind-mounted until it exists.
This bind-mounting happens on Google's ContainerOS, which is why it
isn't always seen.
We still need the reflect helpers, but we allow for clients to
register their own pretty-printers, which avoids the package
dependency for our pretty-printer. We register our pretty printers in
an init function in the relevant package (in this case,
upup/pkg/fi/printers.go)
Fix#5551
a) The current implementation use's a static kubelet which doesn't not conform to the Node authorization mode (i.e. system:nodes:<nodename>)
b) As present the kubeconfig is static and reused across all the masters and nodes
The PR firstly introduces the ability for users to use bootstrap tokens and secondly when enabled ensure the kubelets for the masters as have unique usernames. Note, this PR does not attempt to address the distribution of the bootstrap tokens themselves, that's for cluster admins. One solution for this would be a daemonset on the masters running on hostNetwork and reuse dns-controller to annotated the pods and give as the DNS
Notes:
- the master node do not use bootstrap tokens, instead given they have access to the ca anyhow, we generate certificates for each.
- when bootstrap token is not enabled the behaviour will stay the same; i.e. a kubelet configuration brought down from the store.
- when bootstrap tokens are enabled, the Nodes sit in a timeout loop waiting for the configuration to appear (by third party).
- given the nodeup docker and manifests builders are executed before the kubelet builder, the assumption here is a unit file kicks of a custom container to bootstrap the rest.
- the current firewalls on between the master and nodes are fairly open so no need to open ports between the two
- much of the work was ported from @justinsb PR [here](https://github.com/kubernetes/kops/pull/4134/)
- we add a very presumptuous server and client certificates for use with an authorizer (node-bootstrap-internal.dns_zone)
I do have an additional PR which performs the entire thing. The process being a node_authorizer which runs on the master nodes via a daemonset, the service implements a series of authorizers (i.e. alwaysallow, aws, gce etc). For aws, the process is similar to how vault authorizes nodes [here](https://www.vaultproject.io/docs/auth/aws.html). Nodeup no then calls out to the node_authorizer on bootstrap and provisions the kubelet.
Kubernetes Prow Robot