Comment 7 for bug 375371

One thing that I'm seeing that may need to be documented, is that this breaks mysql-testsuite in its default configuration.

Because we can no longer let /usr/sbin/mysqld write to /tmp at will, the test suite won't start without some coaxing. This works

sudo -u mysql /usr/lib/mysql-test/mysql-test-run.pl --vardir=/var/tmp/mysql

Or, if we add this to the apparmor profile:

  # for the testing suite
  owner @{HOME}/tmp/** rwkl,
  owner @{HOME}/tmp/ rw,

Then we can start it as any user with just

/usr/lib/mysql-test/mysql-test-run.pl --vardir=$HOME/tmp

The mysql user runs with $HOME == /nonexistent, so this should be safe.