After charm upgrade, adding networking-tools PPA fails due to add-apt-repo not using proxy

[Zachary Zehring]

Scenario
========
Upgrade of neutron-openvswitch charm to the latest revision 282 (at the time at least) with the new enable-auto-restarts set to False. The juju action run-deferred-hooks was ran against the unit during a planned Maintenance Window.

Problem
=======
The run-deferred-hooks action hung for ~10 mins and finally failed. From the logs:

2021-05-17 20:51:44 DEBUG restart-services Cannot add PPA: 'ppa:~openstack-charmers/ubuntu/networking-tools'.
2021-05-17 20:51:44 DEBUG restart-services ERROR: '~openstack-charmers' user or team does not exist.
2021-05-17 20:51:44 DEBUG jujuc server.go:211 running hook tool "juju-log"
2021-05-17 20:51:44 INFO juju-log Failed executing 'add-apt-repository --yes ppa:openstack-charmers/networking-tools'. Will retry in 10 seconds

I found there was a recent commit that removed the passing of proxy settings to the "add-apt-repository" command when series was not xenial or trust [0].

Workaround
==========
Manually hacked the charmhelpers code for the unit to include passing proxy vars to the command. This was taken from the new commit.

Obviously, this bug will be fixed on a new release of charmhelpers library. This bug helps with posterity of the issue. I'd imagine this is not the only openstack charm affected by this issue, but it's the only one I've hit it on yet.

[0] https://github.com/juju/charm-helpers/commit/ba4dae4e7bba607f3e5b855d58f1594b39bf3466

[Billy Olsen (billy-olsen)]

Link to in flight reviews - https://review.opendev.org/c/openstack/charm-neutron-openvswitch/+/791167

[Billy Olsen (billy-olsen)]

Actually, this was fix released with https://review.opendev.org/c/openstack/charm-neutron-openvswitch/+/799266