Add external_vip_interface precheck

At this moment prechecks pass even external_vip_interface
is not present or active.
This change adds such precheck into haproxy role.

Change-Id: I7a5ac4aca7002ff8376710ab536b975c88edebc6
Closes-Bug: #1668489

ansible/roles/haproxy/tasks/precheck.yml

@@ -34,6 +34,18 @@
   changed_when: False
   always_run: True
 
+- name: Checking the kolla_external_vip_interface is present
+  fail: "msg='Please check the kolla_external_vip_interface property - interface {{ kolla_external_vip_interface }} not found'"
+  when:
+    - haproxy_enable_external_vip | bool
+    - kolla_external_vip_interface not in ansible_interfaces
+
+- name: Checking the kolla_external_vip_interface is active
+  fail: "msg='Please check the kolla_external_vip_interface settings - interface {{ kolla_external_vip_interface }} is not active'"
+  when:
+    - haproxy_enable_external_vip | bool
+    - hostvars[inventory_hostname]['ansible_' + kolla_external_vip_interface]['active'] != True
+
 - name: Checking if kolla_internal_vip_address and kolla_external_vip_address are not pingable from any node
   command: ping -c 3 {{ item }}
   register: ping_output