Define pod priority for coredns deployment

[dlipovetsky]

As of 1.11, coredns is the kubeadm default. But unlike kubedns, coredns has neither pod priority nor the experimental "critical pod" annotation.

The annotation is deprecated in 1.13, and kubeadm may define pod priority for coredns in 1.14.

[dlipovetsky]

@ojmhetar @sarun87 Your thoughts?

[ojmhetar]

It seems that kube-dns never had the critical pod annotation, so the behavior would be consistent as 1.10? ¯\_(ツ)_/¯

An option could be to apply a patch.

I submitted kubernetes/kubernetes#73649 for the future.

[dlipovetsky]

Thanks for fixing upstream.

I think it's worth patching. Just to note, I'd prefer patching from cctl, rather than nodeadm.