Adjust ProxySQL shunning behavior for single-node clusters

In single-node clusters, ProxySQL shuns the server on MySQL
errors, causing failures during upgrades or container restarts.
This change increases the timeout to 10 seconds, allowing
the backend time to recover and preventing immediate errors
in CI environments.

Change-Id: I70becdc3fcb4ca8f7ae31d26097d95bdc6dd67eb

ansible/group_vars/all.yml

@@ -526,6 +526,20 @@ mariadb_monitor_galera_healthcheck_max_timeout_count: "2"
 mariadb_monitor_ping_interval: "3000"
 mariadb_monitor_ping_timeout: "2000"
 mariadb_monitor_ping_max_failures: "2"
+#
+# Defaults preserved for multinode setup
+# Tweaked for single-node
+#
+# ProxySQL shuns servers on MySQL errors, which can cause failures
+# during upgrades or restarts. In single-node setups, ProxySQL can't reroute
+# traffic, leading to "Max connect timeout" errors. To avoid this in CI and
+# signle-node environments, delay error responses to clients by 10 seconds,
+# giving the backend time to recover without immediate failures.
+#
+# See ProxySQL docs for more: https://proxysql.com/documentation/global-variables/mysql-variables/#mysql-shun_on_failures
+mariadb_shun_on_failures: "{{ '10' if mariadb_shards_info.shards.values() | map(attribute='hosts') | map('length') | select('<=', 1) | list | length > 0 else '5' }}"
+mariadb_connect_retries_delay: "{{ '1000' if mariadb_shards_info.shards.values() | map(attribute='hosts') | map('length') | select('<=', 1) | list | length > 0 else '1' }}"
+mariadb_connect_retries_on_failure: "{{ '20' if mariadb_shards_info.shards.values() | map(attribute='hosts') | map('length') | select('<=', 1) | list | length > 0 else '10' }}"
 
 mariadb_datadir_volume: "mariadb"
 

ansible/roles/loadbalancer/templates/proxysql/proxysql.yaml.j2

@@ -20,6 +20,9 @@ mysql_variables:
    threads: {{ proxysql_workers }}
    max_connections: {{ proxysql_max_connections }}
    interfaces: "{{ kolla_internal_vip_address | put_address_in_context('url') }}:{{ database_port }}"
+   connect_retries_delay: "{{ mariadb_connect_retries_delay }}"
+   connect_retries_on_failure: "{{ mariadb_connect_retries_on_failure }}"
+   shun_on_failures: "{{ mariadb_shun_on_failures }}"
    monitor_username: "{{ mariadb_monitor_user }}"
    monitor_password: "{{ mariadb_monitor_password }}"
    monitor_connect_interval: "{{ mariadb_monitor_connect_interval }}"

releasenotes/notes/proxysql-option-shun-on-failures-559781bbee1235e2.yaml

@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    Added options to configure ``mariadb_shun_on_failures``,
+    ``mariadb_connect_retries_delay``, and
+    ``mariadb_connect_retries_on_failure`` for enhanced
+    control over ProxySQL's shun behavior. These
+    adjustments help manage failover responses effectively.
+    For more details, see `Proxysql Documentation
+    <https://proxysql.com/documentation/global-variables/mysql-variables/>`__