WARNING: This is for proof-of-concept demonstration only.

This can be scheduled via the ProxySQL Scheduler like this:

INSERT INTO scheduler(id, active, interval_ms, filename) values (1, 1, 10000, '/tmp/proxysql-tidb');
LOAD SCHEDULER TO RUNTIME;
SAVE SCHEDULER TO DISK;

You then should check journalctl -u proxysql -f or elswhere for output.

What this does is to do a soft offline of TiDB servers that are in a graceful shutdown.

This require the TiDB server to have a non-zero graceful-wait-before-shutdown

Possible future improvements:

• Logging via slog
• More defensive coding and error checking
• Also onlineing servers when they are healty again
• Adding hostgroup filtering

Other possible solutions:

• pingcap/tidb#58008: Let TiDB no longer respond with OK on COM_PING during shudown.
• Add a global variable for the server health/shutdown status. See pingcap/tidb#58007.