Fix the set_hostnames role when using default inventory behaviour

Some time ago, the openstack inventory would show have as hostvars
id the server name.
That behaviour changed, and now the id is the server uuid, which
breaks the set_hostnames logic.
This change fixes it.

Change-Id: Ie958a9d04fdfeabfab64100e43a4ead44b82a7b8

roles/set_hostnames/tasks/main.yml

@@ -1,16 +1,22 @@
 ---
+- name: Get hostname from server name
+  set_fact: server_hostname={{ inventory_hostname.partition('.')[0] }}
+- name: Get server UUID from dynamic inventory
+  set_fact: server_uuid={{ groups[inventory_hostname][0] }}
+- name: Get server IP
+  set_fact: server_ip={{ hostvars[server_uuid]['openstack']['public_v4'] }}
 # Set hostname and /etc/hosts
 # Inspired by:
 # https://github.com/ansible/ansible/pull/8482)
 # https://gist.github.com/rothgar/8793800
 - name: Set /etc/hostname
-  hostname: name="{{ inventory_hostname.split('.', 1)[0] }}"
+  hostname: name="{{ server_hostname }}"
 
 # " lovely lonely double-quote for fixing vim highlighting
 
 - name: Add all infra hosts to /etc/hosts
   lineinfile: dest=/etc/hosts
-              line='{{ hostvars[item]['openstack']['private_v4'] }} {{ item }} {{ item.split('.', 1)[0] }}'
+              line='{{ server_ip }} {{ item }} {{ server_hostname }}'
               insertafter='^127\.0\.0\.1'
               state=present
   with_items: groups['infra']