kubernetes: kubeadm: preflight check false positives in CentOS 7

Platform: CentOS 7.2.1511 on AWS EC2 (t2.medium)

kubeadm version: version.Info{Major:“1”, Minor:“5+”, GitVersion:“v1.5.0-alpha.2.380+85fe0f1aadf91e”, GitCommit:“85fe0f1aadf91e134102cf3c01a9eed11a7e257f”, GitTreeState:“clean”, BuildDate:“2016-11-02T14:58:17Z”, GoVersion:“go1.7.1”, Compiler:“gc”, Platform:“linux/amd64”}

Symptoms:

While following installation instructions at http://kubernetes.io/docs/getting-started-guides/kubeadm/, I am finding that I need to always disable preflight checks due to spurious failures.

With kubeadmin --init:

preflight check errors:
	ebtables not found in system path

This error appears on all CentOS machines on AWS I’ve tried. It doesn’t seem to relate to anything at all that I can find; the only google hit I can get on it is a Kubernetes issue explaining how to use --skip-preflight-checks. It does not seem to block kubeadmin setup.

On the nodes I get an additional error:

preflight check errors:
	/etc/kubernetes is not empty
	ebtables not found in system path

Indeed, /etc/kubernetes is not empty … because the RPMs distributed by Kubernetes.io include a sub-directory in that dir, “manifests”.