provide facility to deprecate config keys

[Peter Jose De Sousa]

Hi,

With reference to https://github.com/juju-solutions/layer-docker/pull/137, when config keys have already been established, there is no way to provide a migration path between charm versions.

It would be nice to be able to `alias` between config keys of newer and older versions of charms.

E.G.

`charm changed config_key to config-key`

... config.yml
...
aliases:
  - - config_key:
        to: config-key.
...

[Richard Harding (rharding)]

I thought we had something around this in the bugs history but my search-fu fails me.

Thanks for the bug report. Definitely something that's come up a couple of times.

[Canonical Juju QA Bot (juju-qa-bot)]

This bug has not been updated in 2 years, so we're marking it Low importance. If you believe this is incorrect, please update the importance.