Comment 15 for bug 1871981

Hi OpenStack team,

I'll add more details about how this bug blocked charm upgrades.

1). As BootStack charm upgrade policy, we have to upgrade charms per release. For example, in my situation, cloud is at 19.07, to upgrade to 20.05, we have to perform 3 upgrades:

- 19.07 -> 19.10
- 19.10 -> 20.02
- 20.02 -> 20.05

2). In theory, we can not leave an important charm (e.g.: barbican-vault) in error and just upgrade it to latest. We have to fix the error and move on to next release. So the real upgrade process for us will be:

19.07 -> 19.07 + bugfix --> 19.10 + bugfix --> 20.02 + bugfix -> 20.05

3). The bugfix commit (f6546dda33636bca1a94cbce7736b350f64ab74a) is merged into master, and released to 20.05, but not backported to old releases/branches 19.07/19.10/20.02.

4). I tried to clone the charm barbican-vault repo, cherry-pick above commit to 19.07/19.10/20.02 and rebuild the charm myself. But cherry-pick failed with conflicts.

5). Although the conflicts could be easy to resolve in git, but since our maintenance window is in limited timeslot, after investigation to figure out above situation, time is not enough to finish all 3 upgrades. And we didn't test the cherry-pick which is also risky. So after talk with my manager, we decided to cancel the upgrades.