Hello List,
i use dovecot 2.2.22 and have the same problem described here: https://dovecot.org/pipermail/dovecot/2017-November/110020.html
I can confirm that sometimes there is a problem with connection to mysql-db, but sometimes not. Reasons for failing are still under investigation by my mates.
My current main problem is, that this fail seems to be a one way ticket for dovecot. Even if mysql is verifyable working again and waiting for connection dovecot stucks furthermore with errors like this:
May 29 07:00:49 hostname dovecot: auth: Error: plain(mail@example.com,xxx.xxx.xx.xxx,<HGI4FVFt2Oy80j3P>): Request 999.7 timed out after 150 secs, state=1
When restarting dovecot all is immediately working again. Is there a way to tell dovecot to restart auth services or reinitialize mysql-connection after these hard fails? I could insert "idle_kill = 1 mins" into service auth and service auth-worker, but i dont know if this would work. Unfortunately i am not able to reproduce this error and there are always a couple of days between errors.
Thanks, Hajo