dispatch-only charms cannot be deployed, hooks/ directory required

[Stuart Bishop]

A charm containing a dispatch script in its root but no hooks/* scripts cannot be deployed with Juju 2.8-rc3. If one or more hooks/* links are created, it works as intended (for all hooks, not just the ones linked)

$ ls -al dispatch
-rwxrwxr-x 1 stub stub 603 Jun 2 18:14 dispatch

$ juju deploy .
ERROR invalid charm "plinth": has no hooks

$ mv foo hooks

$ ls -al hooks/
total 11
drwxrwxr-x 2 stub stub 5 Jun 1 21:54 .
drwxrwxr-x 11 stub stub 34 Jun 3 13:26 ..
lrwxrwxrwx 1 stub stub 11 Jun 1 21:54 install -> ../dispatch
lrwxrwxrwx 1 stub stub 11 Jun 1 21:54 start -> ../dispatch
lrwxrwxrwx 1 stub stub 11 Jun 1 21:54 upgrade-charm -> ../dispatch

stub@aargh:~/charms/plinth (operator-zaza %)$ juju deploy .
Deploying charm "local:focal/plinth-0".

[Heather Lanigan (hmlanigan)]

PR for 2.8 branch https://github.com/juju/juju/pull/11666

[Tim McNamara (tim-clicks)]

FWIW there was a process failure when the hooks directory was made mandatory. Our docs currently lie. Perhaps they always have. From https://discourse.juju.is/t/charm-metadata/1043

    The only file that must be present in a charm is metadata.yaml,
    in the root directory. It must be a valid YAML dictionary."