* Add pre-upgrade task for moving credentials file

This reverts commit 7ef9f4df.

* add python interpreter workaround for localhost

Kubernetes makes this namespace automatically, so there is
no need for kubespray to manage it.

* Added retries in pre-upgrade.yml and retries while applying kube-dns.yml

* Removed trailing spaces

This file should only be updated during kubelet upgrade so that
master components are not accidentally restarted first during
preinstall stage.

Labels from role (node-role.k8s.io/node) and labels from inventory are merged into node-labels parameter in kubelet

Addition of the .creds extension to the credentials files generated by password lookup in order for Ansible not to consider them as inventory files with inventory_ignore_extensions set accordingly (#2446)

As requested

Ensure that kube-apiserver will respond even if one of the nodes are down.

The ability to create dedicated node for ingress nginx controller
host type network for nginx controller

and add from example https://github.com/kubernetes/ingress-nginx/blob/master/docs/examples/static-ip/nginx-ingress-controller.yaml
terminationGracePeriodSeconds: 60

Added CoreDNS to downloads

Updated with labels. Should now work without RBAC too

Fix DNS settings on hosts

Rename CoreDNS service from kube-dns to coredns

Add rotate based on http://edgeofsanity.net/rant/2017/12/20/systemd-resolved-is-broken.html

Updated docs with CoreDNS info

Added labels and fixed minor settings from official yaml file: https://github.com/kubernetes/kubernetes/blob/release-1.9/cluster/addons/dns/coredns.yaml.sed

Added a secondary deployment and secondary service ip. This is to mitigate dns timeouts and create high resitency for failures. See discussion at 'https://github.com/coreos/coreos-kubernetes/issues/641#issuecomment-281174806'

Set dns list correct. Thanks to @whereismyjetpack

Only download KubeDNS or CoreDNS if selected

Move dns cleanup to its own file and import tasks based on dns mode

Fix install of KubeDNS when dnsmask_kubedns mode is selected

Add new dns option coredns_dual for dual stack deployment. Added variable to configure replicas deployed. Updated docs for dual stack deployment. Removed rotate option in resolv.conf.

Run DNS manifests for CoreDNS and KubeDNS

Set skydns servers on dual stack deployment

Use only one template for CoreDNS dual deployment

Set correct cluster ip for the dns server