Charm channel isn't used on upgrade-charm

[Simon Richardson]

Relates to lp:1560520

When using upgrade charm and you don't provide a channel, we fallback to charmrepo.ResolveWithChannel, which attempts to find you the best channel. This can lead to some unexpected results when it determines the best channel.

The application state has the charm channel ("cs-channel") so we could thread that information when doing upgrade charm.

Workaround is to pass the channel to the upgrade-charm command.

[Eric Claude Jones (ecjones)]

Hi Simon,

Are the unexpected results the same as the issue described in lp:1560520, that is, the upgrade command pulls from the stable channel (or best channel) by default when no channel is specified? Like lp:1560520, are we saying that this behavior happens regardless of the channel that was originally used to deploy the charm? If so, then based on your information I guess the proper reproduction steps should be:

1) Deploy a charm from the charm store using a channel other than "stable" (the charm should have later entries in stable)
2) Upgrade the charm without specifying a channel
3) You should see the charm get upgraded from the stable channel and not the original channel from which the charm was deployed

Expected behavior

The upgrade command should, by default when no channel is specified, use the same channel from which the charm was originally deployed.

Does all this sound correct?

[Simon Richardson (simonrichardson)]

Hi Eric,

> are we saying that this behavior happens regardless of the channel that was originally used to deploy the charm?

Indeed, it seems that we don't honour the channel we deployed the charm with and therefore can end up in a confusing state for the operator.

The information you've provided is correct.

[Eric Claude Jones (ecjones)]

https://github.com/juju/juju/pull/9547