Fix RabbitMQ hostname address resolution precheck

Make it require uniqueness of resolution as well to avoid later
issues with RabbitMQ going crazy.

Change-Id: I000ba6c62ab44eac0abdf8d5d1f069adfbc6552f
Closes-bug: #1863363
(cherry picked from commit 5dd9c532c6)

ansible/roles/rabbitmq/tasks/precheck.yml

@@ -57,10 +57,14 @@
   register: rabbitmq_hostnames
   with_items: "{{ groups['rabbitmq'] }}"
 
-- fail: msg="Hostname has to resolve to IP address of api_interface"
+- name: Check if each rabbit hostname resolves uniquely to the proper IP address
-  with_items: "{{ rabbitmq_hostnames.results }}"
+  fail:
+    msg: Hostname has to resolve uniquely to the IP address of api_interface
+  with_subelements:
+    - "{{ rabbitmq_hostnames.results }}"
+    - stdout_lines
   when:
-    - "item.stdout.find(hostvars[item['item']]['ansible_' ~ hostvars[item['item']]['api_interface']]['ipv4']['address']) == -1"
+    - not item.1 is match('^'+hostvars[item.0.item]['ansible_' ~ hostvars[item.0.item]['api_interface']]['ipv4']['address']+'\\b')
 
 - name: Checking free port for outward RabbitMQ
   wait_for:
@@ -114,8 +118,12 @@
   when:
     - enable_outward_rabbitmq | bool
 
-- fail: msg="Hostname has to resolve to IP address of api_interface"
+- name: Check if each rabbit hostname resolves uniquely to the proper IP address
-  with_items: "{{ outward_rabbitmq_hostnames.results }}"
+  fail:
+    msg: Hostname has to resolve uniquely to the IP address of api_interface
+  with_subelements:
+    - "{{ outward_rabbitmq_hostnames.results }}"
+    - stdout_lines
   when:
     - enable_outward_rabbitmq | bool
-    - "item.stdout.find(hostvars[item['item']]['ansible_' ~ hostvars[item['item']]['api_interface']]['ipv4']['address']) == -1"
+    - not item.1 is match('^'+hostvars[item.0.item]['ansible_' ~ hostvars[item.0.item]['api_interface']]['ipv4']['address']+'\\b')

releasenotes/notes/bug-1863363-eb5d0ddd0d0d1090.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Makes RabbitMQ hostname address resolution precheck stronger by
+    requiring uniqueness of resolution to avoid later issues.
+    `LP#1863363 <https://launchpad.net/bugs/1863363>`