munin node config for mysql not working

[Oliver Mueller]

I just installed a fresh Ubuntu 20.04 with mysql and munin.

It previously worked quite well with Ubuntu 18.04, but now the default plugin-conf.d/munin-node file seems to not work anymore for mysql.

Here is the output of it:
# munin-run mysql_commands
DBI connect('mysql;mysql_read_default_file=/etc/mysql/debian.cnf;mysql_connect_timeout=5','root',...) failed: Access denied for user 'root'@'localhost' (using password: YES) at /etc/munin/plugins/mysql_commands line 1071.
Warning: the execution of 'munin-run' via 'systemd-run' returned an error. This may either be caused by a problem with the plugin to be executed or a failure of the 'systemd-run' wrapper. Details of the latter can be found via 'journalctl'.

The mysql section in /etc/munin/plugin-conf.d/munin-node looks like:

[mysql*]
user root
env.mysqlopts --defaults-file=/etc/mysql/debian.cnf
env.mysqluser root
env.mysqlconnection DBI:mysql:mysql;mysql_read_default_file=/etc/mysql/debian.cnf

which will result in an error using e.g. mysql_commands or so.

Changing this section to...

[mysql*]
user root
env.mysqluser debian-sys-maint
env.mysqlconnection DBI:mysql:mysql;mysql_read_default_file=/etc/mysql/debian.cnf

...did the trick for my installation.

The main problem seems to be the mysqluser set to root even though the default file contains only a "debian-sys-maint" user.

[Vivien GUEANT (vivienfr)]

I have the same type of access problem for other plug-ins : "File /tmp/rsyncd.log cannot be read." or "/usr/bin/tail: cannot open '/home/[...].csv' for reading: Permission denied"

Everything worked perfectly with Ubuntu server 18.04, the regression happened after updating to Ubunut server 20.04

Would that be an apparmor limitation ?

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.