Add HA/LB endpoints for kube-apiserver

* Add HA docs for API server.
* Add auto-evaluated internal endpoints and clarify the loadbalancer_apiserver
vars and usecases.
* Use facts for kube_apiserver to not repeat code and enable LB endpoints use.
* Use /healthz check for the wait-for apiserver.
* Use the single endpoint for kubelet instead of the list of apiservers
* Specify kube_apiserver_count to for HA layout

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

roles/kubernetes/master/templates/manifests/kube-apiserver.manifest.j2

@@ -13,7 +13,8 @@ spec:
     - apiserver
     - --advertise-address={{ ip | default(ansible_default_ipv4.address) }}
     - --etcd-servers={{ etcd_access_endpoint }}
-    - --insecure-bind-address={{ kube_apiserver_insecure_bind_address | default('127.0.0.1') }}
+    - --insecure-bind-address={{ kube_apiserver_insecure_bind_address }}
+    - --apiserver-count={{ kube_apiserver_count }}
     - --admission-control=NamespaceLifecycle,NamespaceExists,LimitRanger,SecurityContextDeny,ServiceAccount,ResourceQuota
     - --service-cluster-ip-range={{ kube_service_addresses }}
     - --client-ca-file={{ kube_cert_dir }}/ca.pem

roles/kubernetes/master/templates/manifests/kube-controller-manager.manifest.j2

@@ -11,7 +11,7 @@ spec:
     command:
     - /hyperkube
     - controller-manager
-    - --master=http://127.0.0.1:{{kube_apiserver_insecure_port}}
+    - --master={{ kube_apiserver_endpoint }}
     - --leader-elect=true
     - --service-account-private-key-file={{ kube_cert_dir }}/apiserver-key.pem
     - --root-ca-file={{ kube_cert_dir }}/ca.pem

roles/kubernetes/master/templates/manifests/kube-scheduler.manifest.j2

@@ -12,7 +12,7 @@ spec:
     - /hyperkube
     - scheduler
     - --leader-elect=true
-    - --master=http://127.0.0.1:{{kube_apiserver_insecure_port}}
+    - --master={{ kube_apiserver_endpoint }}
     - --v={{ kube_log_level | default('2') }}
     livenessProbe:
       httpGet: