Bug#898312: Automatic reboot from /etc/cron.daily/apt-compat interferes with later cron.daily scripts
Package: apt
Version: 1.4.8
With sysvinit, automatic reboots issued from unattended-upgrade called
by apt will interfere with other cron.daily scripts.
apt comes with a helper script /etc/cron.daily/apt-compat for
doing maintenance tasks with sysvinit instead of systemd.
If unattended-upgrades is also installed (I have version
0.93.1+nmu1) and Unattended-Upgrade::Automatic-Reboot is set to
true in apt configuration, when a reboot is needed, a shutdown
command will be issued by /usr/bin/unattended-upgrade called by
/usr/lib/apt/apt.systemd.daily called by /etc/cron.daily/apt-compat.
After the shutdown process is finished (i.e. during shutdown), other
cron.daily scripts with names alphabetically after apt-compat are
called. They may called with some essential services already stopped
(which may break things), may be aborted mid-run, or may not run at
all on this day.
Here's how to reproduce the incorrect behaviour:
apt-get install sysvinit-core unattended-upgrades
shutdown -r now
apt-get purge systemd
cat <<EOF >/etc/apt/apt.conf.d/75local
Unattended-Upgrade::Automatic-Reboot "true";
Unattended-Upgrade::Automatic-Reboot-WithUsers "true";
EOF
cat <<EOF >/etc/cron.daily/z-i-am-last
#!/bin/sh
sleep 3600
/usr/bin/logger "z-i-am-last finished"
EOF
Wait for an upgrade that requires a reboot. z-i-am-last will
(probably) not complete on the day of the unattended reboot.
Expected behaviour:
In the scenario above, z-i-am-last logs its message exactly once a day.
Suggested fix:
An easy way to fix this would be to rename /etc/cron.daily/apt-compat
to /etc/cron.daily/zz-apt-compat to make sure this script is run
after all the other daily scripts, at the same time indicating to
the sysadmin that order is important.
As a beneficial side effect, this would reduce the severity of things
like #829443, and greatly reduce the motivation for the sysadmin to
set APT::Periodic::RandomSleep to zero.
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