ceph-admin interface is experimental

[Ryan Beisner]

The kubernetes-master charm [0] incorporates the ceph-admin interface[1], which is unofficial, unreleased, not maintained, and is an experimental interface. The ceph-admin interface is not in use by the official OpenStack/Ceph charms, and its code lives in an inactive individual's personal repo.

I think we should look at what needs are being filled by this interface and look at other methods to achieve those needs which are more in line with the maintained Ceph charms. That, or take this interface into a maintained product state if no other existing approaches fill the needs here.

- "interface:ceph-admin" [1]

[0] https://api.jujucharms.com/charmstore/v5/~containers/kubernetes-master-700/archive/layer.yaml
[1] https://github.com/charmed-kubernetes/charm-kubernetes-master/blob/02ef61456cfd2b24b49109eb5809af9a16b18d4b/layer.yaml#L15

[Ryan Beisner (1chb1n)]

FYI, I've moved the layer repo, updated the layer and layer-index readmes, and updated the layer-index, all to ensure that this codebase is somewhere under team control. However, this doesn't change the experimental and maintenance state of the layer. Those conversations should still take place.

https://github.com/juju/layer-index/pull/87

https://github.com/openstack-charmers/juju-interface-ceph-admin/pull/1

[Cory Johns (johnsca)]

The admin credentials are required by ceph-csi to support CephFS volume provisioning. I believe this is the only reason we require the admin relation currently, though in the past it was needed for RBD as well and there are still some references to that in the charm code that need to be cleaned up.

https://github.com/ceph/ceph-csi/blob/master/docs/deploy-cephfs.md

[George Kraft (cynerva)]

The ceph relations in kubernetes-master will be deprecated in the CK 1.24 release, but the same issue exists in the Ceph CSI charm. Retargeting this bug.

[George Kraft (cynerva)]

PR for kubernetes-control-plane: https://github.com/charmed-kubernetes/charm-kubernetes-control-plane/pull/219

[George Kraft (cynerva)]

PR for Ceph CSI charm: https://github.com/charmed-kubernetes/ceph-csi-operator/pull/1