Do not use group as a "setup_host" variable

This fixes an issue, when a host group was passed to mq_setup role,
and delegate logic uses group name instead of host inside of the
group for delegating tasks.

While this patch might break already in-place workarounds, it's
quite important to fix the issue properly, as workarounds are not
trivial and requires quite some understanding of the process.

Closes-Bug: #2111406
Change-Id: Ic5747e29050cced51a71a4b4e71352f231758ed8

defaults/main.yml

@@ -200,6 +200,7 @@ trove_guest_endpoint_type: public
 
 # Guestagent RPC configuration
 trove_guest_rpc_host_group: "{{ oslomsg_rpc_host_group | default('rabbitmq_all') }}"
+trove_guest_oslomsg_rpc_setup_host: "{{ (trove_guest_rpc_host_group in groups) | ternary(groups[trove_guest_rpc_host_group][0], 'localhost') }}"
 trove_guest_oslomsg_rpc_servers: >-
   {{
     groups[trove_guest_rpc_host_group] | map('extract', hostvars, 'ansible_facts') | map(attribute=trove_provider_net_iface | replace('-','_')

releasenotes/notes/trove_rabbitmq_guest_setup_host-b1237ed5efe32431.yaml

@@ -0,0 +1,14 @@
+---
+upgrade:
+  - |
+    When using standalone RabbitMQ cluster for Trove deployment, make sure to
+    use ``trove_guest_rpc_host_group`` as a pointer to host group, rather then
+    a pointer to a specific host.
+    You can use variable ``trove_guest_oslomsg_rpc_setup_host`` to define a
+    specific host which should be responsible for provisionment of RabbitMQ
+    vhost and users instead.
+fixes:
+  - |
+    Variable ``trove_guest_rpc_host_group`` is now used as intended and
+    represents a host group. It is no longer directly used as
+    "delegated host" when configuring a standalone RabbitMQ cluster for Trove.

tasks/main.yml

@@ -100,7 +100,7 @@
     - (trove_oslomsg_rpc_host_group != trove_guest_rpc_host_group) or
       (trove_oslomsg_notify_host_group != trove_guest_notify_host_group and trove_guest_oslomsg_notify_configure)
   vars:
-    _oslomsg_rpc_setup_host: "{{ trove_guest_rpc_host_group }}"
+    _oslomsg_rpc_setup_host: "{{ trove_guest_oslomsg_rpc_setup_host }}"
     _oslomsg_rpc_userid: "{{ trove_guest_oslomsg_rpc_userid }}"
     _oslomsg_rpc_password: "{{ trove_guest_oslomsg_rpc_password }}"
     _oslomsg_rpc_vhost: "{{ trove_guest_oslomsg_rpc_vhost }}"