Use proxy protocol v2 to send client info to galera backend servers

This configures HAProxy to transmit client info to galera backend servers
and also configures the HAProxy IP address as trusted sources in order for
galera to accept this info.

Depends-On: https://review.opendev.org/c/openstack/openstack-ansible-galera_server/+/854787
Change-Id: Ib445b3847aa4a48a9ebc6aafd97a73f41a1f68dd

inventory/group_vars/galera_all.yml

@@ -38,6 +38,16 @@ galera_monitoring_allowed_source: >-
       | join(' ') ~ ' 127.0.0.1'
   }}
 
+# Accept PROXY protocol information from the load balancers
+# See https://mariadb.com/kb/en/proxy-protocol-support for details
+galera_server_proxy_protocol_networks: >-
+  {{
+    groups['haproxy']
+      | map('extract', hostvars, 'ansible_host')
+      | list
+      | join(',') ~ ', localhost, ::1'
+  }}
+
 # Galera sessions are long lived, so if we do endpoint maintenance we will
 # force kill the sessions to force a failover to the active endpoint.
 haproxy_shutdown_sessions: yes

inventory/group_vars/haproxy/haproxy.yml

@@ -168,6 +168,8 @@ haproxy_galera_service:
   haproxy_timeout_server: 5000s
   haproxy_backend_options:
     - "httpchk HEAD / HTTP/1.0\\r\\nUser-agent:\\ osa-haproxy-healthcheck"
+  haproxy_backend_server_options:
+    - "send-proxy-v2"
   haproxy_allowlist_networks: "{{ haproxy_galera_allowlist_networks }}"
   haproxy_service_enabled: "{{ groups['galera_all'] is defined and groups['galera_all'] | length > 0 }}"