kubeadm: resolve the cmd/kubeadm/app/util/system dependecy problems

this is part of the kubeadm dep cleanup. xref https://github.com/kubernetes/kubeadm/issues/1600

item 1: (RESOLVED)

PRs: https://github.com/kubernetes/kubernetes/pull/79449

in app/util/system/docker_validator.go we depend on the docker API and client to do some checks.

for kubeadm we don’t really need to make this client call because we can use docker info instead. if e2e_node are happy with that we can go this route and stop importing the docker API / client in kuberentes as a whole (minus dockershim, for now).

proposed solution:

• use docker info

item 2: (RESOLVED)

REPO was created: https://github.com/kubernetes/system-validators

/test/e2e_node/e2e_node_suite_test.go imports k8s.io/kubernetes/cmd/kubeadm/app/util/system

for the sake of running system validators. originally these lived in e2e_node but were moved to /cmd/kubeadm as kubeadm was the only user.

then at some point e2e_node started importing them again.

proposed solution:

• move these utils to a new repo: k8s.io/system-validators

item 3: (RESOLVED)

remove klog and util/errors dependencies from the kubeadm system-validators https://github.com/kubernetes/kubeadm/issues/1738

item 4: (RESOLVED)

start using the new repo.

• copy the validtors from k/kubernetes/cmd/kubeadm to kubernetes/system-validators PR: https://github.com/kubernetes/system-validators/pull/1
• tag the new repo and create a branch for 1.15?
• use the validators from the new system-validators repo in k/kubernetes/cmd/kubeadm and /test/e2e_node PR: https://github.com/kubernetes/kubernetes/pull/84718