[Bug 2121021] Re: apt-daily-upgrade.timer unexpectedly stops MySQL service on Ubuntu/Debian.

[Julian Andres Klode]

Reassigned to mysql-defaults, but marking as incomplete, MySQL 5.7
certainly is a very outdated MySQL version that's not available in any
release of Ubuntu still in standard support.

** Package changed: apt (Ubuntu) => mysql-defaults (Ubuntu)

** Changed in: mysql-defaults (Ubuntu)
       Status: New => Incomplete

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Title:
  apt-daily-upgrade.timer unexpectedly stops MySQL service on
  Ubuntu/Debian.

Status in mysql-defaults package in Ubuntu:
  Incomplete

Bug description:
  The apt-daily-upgrade.timer is causing the MySQL service to shut down
  repeatedly and unexpectedly. The service starts successfully but is
  then stopped within seconds of a scheduled apt-daily-upgrade.timer
  run.

  This behavior is caused by a systemd timer unintentionally calling an
  outdated /etc/init.d/mysql script. The script contains killall
  commands intended as a fail-safe for graceful shutdowns, but in this
  context, they are being executed by the apt-daily process, which
  forcefully terminates the MySQL service.

  Steps to Reproduce
  This issue was diagnosed using the following steps, which can be used to observe the behavior:

  Monitor the MySQL service status using systemctl status mysql.

  sudo systemctl status mysql
  Observe the systemd journal logs, filtered for the mysql.service, which show the unexpected shutdowns coinciding with apt processes.

  sudo journalctl -u mysql.service --since "1 day ago"
  (Example log output showing the issue):

  Aug 20 06:25:04 ip-172-31-27-102 systemd[1]: Starting mysql.service - MySQL Community Server...
  Aug 20 06:25:11 ip-172-31-27-102 systemd[1]: Started mysql.service - MySQL Community Server.
  Aug 20 06:25:14 ip-172-31-27-102 apt.systemd.daily[160407]: ...
  Aug 20 06:25:16 ip-172-31-27-102 systemd[1]: Stopping mysql.service - MySQL Community Server...
  Aug 20 06:25:17 ip-172-31-27-102 systemd[1]: Stopped mysql.service - MySQL Community Server.
  Inspect the /etc/init.d/mysql script to find the killall commands that are responsible for the forceful shutdown.

  sudo cat /etc/init.d/mysql
  (Relevant lines from script):

  # Short-Description: Start and stop the mysql database server daemon
  ...
  killall -15 mysqld
  if test -z "$server_down"; then killall -9 mysqld; fi
  Environment Details
  Operating System: Debian/Ubuntu (based on apt, phpsessionclean.service and /etc/init.d/ file structure).

  MySQL Version: 5.7+ (based on /usr/share/doc/mysql-server-5.7/ path in
  the script).

  Proposed Solution / Workaround
  The issue can be resolved by performing two steps:

  Modify the legacy /etc/init.d/mysql script by commenting out the
  killall commands. This prevents the script from having the ability to
  forcefully shut down the service.

  
  sudo nano /etc/init.d/mysql
  Change the lines to:

  #            killall -15 mysqld
  #          if test -z "$server_down"; then killall -9 mysqld; fi
  Disable the apt-daily-upgrade.timer to prevent the unintentional execution of the legacy script.

  
  sudo systemctl disable --now apt-daily-upgrade.timer

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