Comment 5 for bug 1652848

This one is held up because, in order to patch the stable/18.05 charms, we need to put the feature into master and patch stable/18.11, stable/18.08 as well as stable/18.05. This is because if an operator upgrades their charms it shouldn't break the functionality; i.e. as it stands now, there would be a regression if the op upgraded from stable/18.05 to any newer charm.

Please could a separate review be raised for master with the feature, and once that has landed, it can be backported using a cherry-pick to 18.11, 18.08 and then 18.05.

Thanks.