Enable RabbitMQ feature flags pre-upgrade

This task must be carried out before any RabbitMQ instances are
stopped, so must live in the playbook as opposed to the role.

This complements the post-upgrade enablement which happens within
the role itself, and covers the case where older versions of the
role have not already enabled the relevant flags.

Depends-On: https://review.opendev.org/c/openstack/openstack-ansible-rabbitmq_server/+/919701
Change-Id: Idf33b6810e1afb3a89dad5e65a48e86ac0a58a67

playbooks/rabbitmq-install.yml

@@ -43,6 +43,19 @@
   tags:
     - rabbitmq
 
+# Stable feature flags must be enabled pre-upgrade
+# https://www.rabbitmq.com/docs/feature-flags#version-compatibility
+- name: Enable stable feature flags pre-upgrade
+  hosts: "{{ rabbitmq_host_group | default('rabbitmq_all') }}[0]"
+  gather_facts: false
+  user: root
+  tasks:
+    - name: Running feature flags tasks from the role
+      import_role:
+        name: rabbitmq_server
+        tasks_from: rabbitmq_feature_flags.yml
+      when: rabbitmq_upgrade | default(false) | bool
+
 # The cluster must be stopped when doing major/minor upgrades
 # http://www.rabbitmq.com/clustering.html#upgrading
 - name: Stop RabbitMQ nodes that are not the upgrader

releasenotes/notes/rabbitmq-feature-flags-d1a0f3fd4e17cbf4.yaml

@@ -0,0 +1,5 @@
+---
+upgrade:
+  - |
+    Stable RabbitMQ feature flags will be enabled automatically pre-upgrade
+    in order to prevent failures during the upgrade process.