Run a command before & after ubuntu apt upgrade & unattended-upgrades

Question

On an Ubuntu 16.04.3 LTS server I run some process monitors, but I also run apt manually as well as unattended-upgrades for security updates.

This sometimes causes the monitors to report and act on programs that were stopped by apt during apt upgrade.

Is there a way to run a command when unattended-upgrades/apt starts the upgrades (to stop the monitors) and again when unattended-upgrades/apt finishes (to restart the monitors)?

I found APT::Update::Pre-Invoke and APT::Update::Post-Invoke hooks but the apt update step is not the problem, and apt itself does not seem to have any pre/post upgrade hooks.

Answer 1

There are three hooks you can use for this:

• DPkg::Pre-Invoke is run once, before all the package manipulation sequences in one apt invocation;
• DPkg::Pre-Install-Pkgs is also run once, before the package manipulation sequences, after the Pre-Invoke hook, and with a list of all the packages which will be installed;
• DPkg::Post-Invoke is run once, after the package manipulation sequences.

The documentation isn’t all that clear (do read man apt.conf though), but reading the source code supports the above. Specifying hooks also confirms this (for example, this is how apt-listbugs works).