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name: charmed-openstack-upgrader
description: Automatic upgrade tool for Charmed Openstack
AFAIK the juju-bin slot is provided by the juju snap, exposing whatever the juju snap has under its bin directory.
If I understand it correctly, you want the charmed-openstack-upgrader snap to be able to auto-connect to this slot and consume the files exposed by juju. If that’s the case, I think it should work without any special permission as both snaps juju and charmed-openstack-upgrader are published by Canonical.
Regarding the personal-files interface, the requested directory seems to belong to juju rather than charmed-openstack-upgrader. However, considering that both are published by the same entity I’m happy to give a +1 (#voteFor)