Add etcd proxy support

* Enforce a etcd-proxy role to a k8s-cluster group members. This
provides an HA layout for all of the k8s cluster internal clients.
* Proxies to be run on each node in the group as a separate etcd
instances with a readwrite proxy mode and listen the given endpoint,
which is either the access_ip:2379 or the localhost:2379.
* A notion for the 'kube_etcd_multiaccess' is: ignore endpoints and
loadbalancers and use the etcd members IPs as a comma-separated
list. Otherwise, clients shall use the local endpoint provided by a
etcd-proxy instances on each etcd node. A Netwroking plugins always
use that access mode.
* Fix apiserver's etcd servers args to use the etcd_access_endpoint.
* Fix networking plugins flannel/calico to use the etcd_endpoint.
* Fix name env var for non masters to be set as well.
* Fix etcd_client_url was not used anywhere and other etcd_* facts
evaluation was duplicated in a few places.
* Define proxy modes only in the env file, if not a master. Del
an automatic proxy mode decisions for etcd nodes in init/unit scripts.
* Use Wants= instead of Requires= as "This is the recommended way to
hook start-up of one unit to the start-up of another unit"
* Make apiserver/calico Wants= etcd-proxy to keep it always up

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>
Co-authored-by: Matthew Mosesohn <mmosesohn@mirantis.com>

roles/etcd/handlers/main.yml

@@ -6,6 +6,13 @@
     - start etcd
     - reload etcd
 
+- name: restart etcd-proxy
+  command: /bin/true
+  notify:
+    - reload systemd
+    - start etcd-proxy
+    - reload etcd-proxy
+
 - name: reload systemd
   command: systemctl daemon-reload
   when: ansible_service_mgr == "systemd"
@@ -15,8 +22,23 @@
     name: etcd
     enabled: yes
     state: started
+  when: is_etcd_master
+
+- name: start etcd-proxy
+  service:
+    name: etcd-proxy
+    enabled: yes
+    state: started
+  when: is_etcd_proxy
 
 - name: reload etcd
   service:
     name: etcd
     state: "{{ 'restarted' if etcd_deployment_type == 'host' else 'reloaded' }}"
+  when: is_etcd_master
+
+- name: reload etcd-proxy
+  service:
+    name: etcd-proxy
+    state: "{{ 'restarted' if etcd_deployment_type == 'host' else 'reloaded' }}"
+  when: is_etcd_proxy