[#MXS-4425] Support config sync with Xpand

Xpand doesn't have a mysql database and it does not implement the current set of JSON functions that MaxScale uses. Support for config synchronization can be added by making the database configurable (~~MXS-4499~~) and changing the SQL to do the JSON manipulation in MaxScale.

Original description:

Environment

Xpand 6.0.5
MaxScale Version: 6.4.4

Steps to Reproduce

1. Set up Xpand and then run this SQL:

CREATE DATABASE mysql;

GRANT ALL on mysql.* TO 'sync_user'@'%' IDENTIFIED BY 'secure_password';

2. Set up MaxScale Clustering with this config:

# Globals

[maxscale]

config_sync_cluster = XpandMonitor

config_sync_user = sync_user

config_sync_password = secure_password

3. View the MaxScale Logs

Observed Behavior

This error is repeated every five seconds:

2022-12-02 21:44:29   warning: (ConfigManager); Failed to update node state to ‘Failed to update server ‘XpandBootstrap’’ for hostname ‘ip-10-0-0-48.us-east-2.compute.internal’: Query ‘UPDATE mysql.maxscale_config SET nodes = JSON_SET(nodes, CONCAT(‘$.’, JSON_QUOTE(‘ip-10-0-0-48.us-east-2.compute.internal’)), ‘Failed to update server \’XpandBootstrap\’’) WHERE version = 1 AND cluster = ‘XpandMonitor’’ failed. Error 1046: [11285] No database selected.

Also, the record is not updated in mysql.maxscale_config

[MXS-4425] Support config sync with Xpand Created: 2022-12-02 Updated: 2023-10-04 Resolved: 2023-10-04
Status:	Closed
Project:	MariaDB MaxScale
Component/s:	N/A
Affects Version/s:	6.4.4
Fix Version/s:	N/A