[#MDEV-25419] In 10.5 mariadbd/mysqld "--help" can change the contents of the datadir.

I noticed this when doing an upgrade from 10.3 to 10.5 – if you try to view the "--help" output after installing 10.5 but prior to starting it, the command would migrate the ib logfiles. Since I was running "mysqld --help" as root, the new ib_logfile0 had root ownership, which prevented mariadb from starting.

It's not a major issue (seems very edge-case) – but it was not clear if it was an intentional change. I was advised to go ahead and file a JIRA case about this in the zulip chat.

Comparing the stderr from the help output on 10.3 vs 10.5 also shows that 10.5 tries to lock datadir files:

[root@redacted1 ~]# systemctl status mariadb.service

● mariadb.service - MariaDB 10.3.28 database server

   Loaded: loaded (/usr/lib/systemd/system/mariadb.service; enabled; vendor preset: disabled)

  Drop-In: /etc/systemd/system/mariadb.service.d

           └─migrated-from-my.cnf-settings.conf

   Active: active (running) since Tue 2021-04-06 10:10:57 CDT; 16min ago

     Docs: man:mysqld(8)

           https://mariadb.com/kb/en/library/systemd/

 Main PID: 4887 (mysqld)

   Status: "Taking your SQL requests now..."

   CGroup: /system.slice/mariadb.service

           └─4887 /usr/sbin/mysqld

Apr 06 10:10:56 redacted1 systemd[1]: Starting MariaDB 10.3.28 database server...

Apr 06 10:10:57 redacted1 mysqld[4887]: 2021-04-06 10:10:57 0 [Note] /usr/sbin/mysqld (mysqld 10.3.28-MariaDB) starting as process 4887 ...

Apr 06 10:10:57 redacted1 systemd[1]: Started MariaDB 10.3.28 database server.

[root@redacted1 ~]#

[root@redacted1 ~]# mysqld --defaults-file=/etc/my.cnf --help --verbose >/dev/null

2021-04-06 10:27:24 0 [Note] Plugin 'FEEDBACK' is disabled.

2021-04-06 10:27:24 0 [Warning] Could not open mysql.plugin table. Some options may be missing from the help text

[root@redacted2 ~]# systemctl status mariadb.service

● mariadb.service - MariaDB 10.5.9 database server

   Loaded: loaded (/usr/lib/systemd/system/mariadb.service; enabled; vendor preset: disabled)

  Drop-In: /etc/systemd/system/mariadb.service.d

           └─migrated-from-my.cnf-settings.conf

   Active: active (running) since Tue 2021-04-06 09:20:25 CDT; 1h 7min ago

     Docs: man:mariadbd(8)

           https://mariadb.com/kb/en/library/systemd/

  Process: 6102 ExecStartPost=/bin/sh -c systemctl unset-environment _WSREP_START_POSITION (code=exited, status=0/SUCCESS)

  Process: 6061 ExecStartPre=/bin/sh -c [ ! -e /usr/bin/galera_recovery ] && VAR= ||   VAR=`cd /usr/bin/..; /usr/bin/galera_recovery`; [ $? -eq 0 ]   && systemctl set-environment _WSREP_START_POSITION=$VAR || exit 1 (code=exited, status=0/SUCCESS)

  Process: 6059 ExecStartPre=/bin/sh -c systemctl unset-environment _WSREP_START_POSITION (code=exited, status=0/SUCCESS)

 Main PID: 6087 (mariadbd)

   Status: "Taking your SQL requests now..."

   CGroup: /system.slice/mariadb.service

           └─6087 /usr/sbin/mariadbd

Apr 06 09:20:25 redacted2 systemd[1]: Starting MariaDB 10.5.9 database server...

Apr 06 09:20:25 redacted2 mariadbd[6087]: 2021-04-06  9:20:25 0 [Note] /usr/sbin/mariadbd (mysqld 10.5.9-MariaDB) starting as process 6087 ...

Apr 06 09:20:25 redacted2 systemd[1]: Started MariaDB 10.5.9 database server.

[root@redacted2 ~]#

[root@redacted2 ~]# mysqld --defaults-file=/etc/my.cnf --help --verbose >/dev/null

2021-04-06 10:27:31 0 [ERROR] mysqld: Can't lock aria control file '/var/lib/mysql/aria_log_control' for exclusive use, error: 11. Will retry for 0 seconds

2021-04-06 10:27:31 0 [ERROR] Plugin 'Aria' init function returned error.

2021-04-06 10:27:31 0 [ERROR] Plugin 'Aria' registration as a STORAGE ENGINE failed.

2021-04-06 10:27:31 0 [Warning] Could not open mysql.plugin table: "Unknown storage engine 'Aria'". Some options may be missing from the help text

[root@redacted2 ~]#

I would not expect "mariadbd --help" to attempt to lock the aria log or change any files within the datadir.

[MDEV-25419] In 10.5 mariadbd/mysqld "--help" can change the contents of the datadir. Created: 2021-04-14 Updated: 2021-07-23
Status:	Open
Project:	MariaDB Server
Component/s:	None
Affects Version/s:	10.5
Fix Version/s:	10.5

[MDEV-25419] In 10.5 mariadbd/mysqld "--help" can change the contents of the datadir. Created: 2021-04-14 Updated: 2021-07-23