apply: Fix crash when OVS is stopped (LP#1995598)

[daniloegea]

If openvswitch is installed but not running, netplan apply will try to call the service anyway and will crash. In this case we probably should ignore the error and log a warning message to the user.

Add an integration test that will be executed by autopkgtest.

Description

It addresses https://bugs.launchpad.net/ubuntu/+source/netplan.io/+bug/1995598

The problem can be reproduced with:

lxc launch ubuntu:22.04 jammy --vm
lxc exec jammy bash
apt install openvswitch-switch
systemctl stop ovsdb-server
netplan apply

Checklist

• Runs make check successfully.
• Retains 100% code coverage (make check-coverage).
• New/changed keys in YAML format are documented.
• (Optional) Adds example YAML for new feature.
• (Optional) Closes an open bug in Launchpad.

[slyon]

Let's call it ovsdb-server.service explicitly

[slyon]

Thanks, lgtm!
I added some small bit to call ovsdb-server.service by its explicit name (including the .service suffix). Let's merge it once it passes the tests.

[ali-basafa]

This error is because ovsdb-server.service is not running, and if it is not running, you can install it with
apt-get install openvswitch-switch
systemctl restart ovsdb-server
, and if it is installed, remove it and install it again with the following command.
apt-get remove openvswitch-switch
apt-get install openvswitch-switch
systemctl restart ovsdb-server