* robust handling of API server SANs

* use apiserver_loadbalancer_domain_name if it is defined, according to PR 3977

The iteritems() dictionary's method has been removed in Python3. Using
this method in Jinja2 templates limits the execution to Python2 which
will be deprecated in 2020[1]. This change replaces that method for
the items() method as it's suggested in the official website[2].

[1] https://pythonclock.org/
[2] https://docs.ansible.com/ansible/latest/user_guide/playbooks_python_version.html#dict-iteritems

* Update CoreDNS to 1.4.0

* Update readme to reflect CoreDNS update

* Update DNS Autoscaler

* Update downloads too

* Fix yamllint

* Fix yamllint

* enable kubelet client certificate rotation

* change to variable kubelet_rotate_certificates

Both the `yum` and `apt` modules support a list as input, this allows us avoid the slower `with_items` approach, which can take a long time with a large count of cluster nodes.

Both kubedns and dnsmasq modes are long not maintained.
We should run dns_late steps at the end because sshd
makes DNS lookups during Ansible run and has 2s timeouts
for each failed lookup trying to connect to coredns before
it is ready.

* Fix jinja2 boolean condition

* Convert all felix variable to booleans instead.

This commit adapts the "Lay Down KubeDNS Template" task to use the static
files moved by pull request [1]

[1] https://github.com/kubernetes-sigs/kubespray/pull/4341

* Fix bootsrap-os role, failing to create remote_tmp

* use ansible_remote_tmp hostvar

values from inventory in roles/kubespray-defaults/defaults/main.yml
hardcoded values in roles/container-engine/defaults/main.yml

dns_servers set empty in roles/container-engine/defaults/main.yml and skydns_server not set in docker_dns_servers variables
also set default value for manual_dns_serve

another variables in roles/container-engine/defaults not need to set

* Added configurable local apiserver proxy liveness probe

* Enable API LB healthcheck by default

* Fix template spacing and moved healthz location to nginx http section

* Fix healthcheck listen address to allow kubelet request healthcheck

This reverts commit ea7a6f1c.

This change modified the certs dir for Kubernetes, but did not move the directories for existing clusters.

Pods on down/unresponsive nodes can't be deleted without
--force --grace-period=0.

Fixes #4314

* Move most coredns templates to static files

This should speed up the task slightly

* yaml lint fixes