Setting extra-ceph-conf just hangs on the CLI

Problem

When I use ceph cephadm set-extra-ceph-conf or ceph cephadm get-extra-ceph-conf the command line just hangs forever.

Solution

Running ceph cephadm set-extra-ceph-conf without any option can corrupt the local value stored and cause the commands to hang. This can be cleaned by removing the internal ceph config-key setting and then restarting the active ceph-mgr:

$ ceph config-key ls
[
    mgr/cephadm/extra_ceph_conf,
]
$ ceph config-key get mgr/cephadm/extra_ceph_conf
{"conf": null, "last_modified": "2024-08-01T23:50:20.959362Z"}
$ ceph config-key rm mgr/cephadm/extra_ceph_conf
key deleted
$ ceph mgr fail