Improve repo server haproxy healthcheck to verify repo synchronisation

This patch updates the healthcheck to test for the presence of the file
/var/www/repo/repo_sync_complete.
This addresses an issue where haproxy would direct traffic to redeployed
repo servers which were correctly serving the web root but had no
meaningful content.
The repo_sync_complete file is created by related changes to the
repo_server ansible role.

Partial-Bug: 1829930
Depends-On: https://review.opendev.org/660788/

Change-Id: Ib7b64b09413fbdd8c630311d437539c9f876fac0

etc/openstack_deploy/openstack_user_config.yml.aio.j2

@@ -140,6 +140,7 @@ shared-infra_hosts:
       galera_container: 3
       memcached_container: 3
       rabbit_mq_container: 3
+      repo_container: 3
 {% endif %}
 
 repo-infra_hosts:

inventory/group_vars/haproxy/haproxy.yml

@@ -68,7 +68,9 @@ haproxy_default_services:
       haproxy_port: 8181
       haproxy_balance_type: http
       haproxy_backend_options:
-        - "httpchk HEAD / HTTP/1.0\\r\\nUser-agent:\\ osa-haproxy-healthcheck"
+        - "httpchk GET /repo_sync_complete HTTP/1.0\\r\\nUser-agent:\\ osa-haproxy-healthcheck"
+      haproxy_backend_httpcheck_options:
+        - "expect status 200"
       haproxy_service_enabled: "{{ groups['repo_all'] is defined and groups['repo_all'] | length > 0 }}"
   - service:
       haproxy_service_name: glance_api

playbooks/healthcheck-infrastructure.yml

@@ -24,9 +24,9 @@
   hosts: all_containers[0]:physical_hosts[0]
   gather_facts: yes
   vars:
-    repo_requirements_file: "os-releases/{{ openstack_release }}/{{ os_distro_version }}/"
+    repo_requirements_file: "repo_sync_complete"
   tasks:
-    - name: Check the upper constraint on each repo server
+    - name: Check the repo sync file on each repo server
       uri:
         url: "http://{{ hostvars[item]['container_address'] }}:{{ repo_server_port }}/{{ repo_requirements_file }}"
       with_inventory_hostnames: "{{ groups['repo_all'] }}"

releasenotes/notes/repo_check-31eb53ae77ddeb41.yaml

@@ -0,0 +1,6 @@
+---
+other:
+  - |
+    HAProxy now verifies if repo server is healthy by ``repo_sync_complete``
+    file that is created with repo_server role. This should prevent
+    non-synced repo containers from participating in load balancing.