athena-auto-update should dpkg --configure -a

[geofft]

A handful of machines in clusters have stopped updating with

E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem. 
E: Couldn't rebuild package cache

update.log is missing a record of the last upgrade finishing, indicating the system was probably rebooted. I reported this as a theoretical bug five months ago in comment:ticket:217:1 after running into it on my -cluster laptop; as I predicted, it's happening in practice.

[jdreed]

From today's release-team:

We decided we don't care about machines being unavailable while they're taking an update. We should change athena-auto-update to run when idle. The desync period should be 2 hours during "low usage" times (2am -8 am) and should be 6 hours otherwise, to help protect against every machine in a cluster taking texlive-full simultaneously.

When a machine is being updated, we will touch /etc/nologin and switch to a new VT and display a message to users.

We should ensure updates run even on machines that get little-to-no idle time, such as quickstations.

This probably also fixes #406 -- if so, someone should close that ticket.

[andersk]

That is not particularly related to this ticket, nor to #406. The updater will need to ‘dpkg --configure -a’ whether or not it is running during during a login session.