Should a replica be restarted as well?

I would like to do this.

In progress...

Syntax is like SHUTDOWN. So it also supports WAIT FOR ALL SLAVES. It will exit with status code 16 so that monitoring/parent process can detect a restart request. Code logic checks to see if MARIADBD_PARENT_PID env is set and corresponding process is alive (linux only) before shutdown. It is compatible with mysql RESTART except that the name of the env has MARIADBD_ as the prefix instead of MYSQLD_.

Could you implement restart completely within the server executable, why does it need support from the calling process?

It is the way MySQL and MaxScale work and was discussed in its zuli thread.

So, two approaches. Simply exit with a special return code or exec itself instead.

Pro exit:

• MySQL and MaxScale do it this way
• allows to measure the uptime since the last restart
• restores resources better (environment and file descriptors, although the server uses O_CLOEXEC anyway)

Pro exec:

• just works, on itself, does not require support in external tools (e.g. mariadbd-safe, systemd, or k8s)
• doesn't restart the container

Okay, let's do exit(16) then