Comment 9 for bug 918386

This bug needs revisiting.

There are many charms that have to manage internal validation of enum-type config.yaml variables that should be handled at the juju client/bundle/validation layer instead of having to re-code enum validation in each charm.

See bug https://bugs.launchpad.net/charm-rabbitmq-server/+bug/1942918 as an example of how operators can easily shoot themselves in the foot without these safety measures.

Having the schema validation for enum-type variables at the client end can prevent config-changed hooks from erroring and causing outage of juju-managed applications.