Comment 8 for bug 1986593

> I can confirm this. But interestingly, it happens only after adding the expected relation:
>
> > - ['ceph-dashboard:radosgw-dashboard', 'ceph-radosgw:radosgw-user']
>
> Before adding the relation the object gateway tab actually works.

At least on my test bed,

[before adding the relation]

# ceph config dump | grep 'dashboard.*KEY'
mgr advanced mgr/dashboard/RGW_API_ACCESS_KEY LWPYOAE08C0V3TL820N6 *
mgr advanced mgr/dashboard/RGW_API_SECRET_KEY 82Ln2K9GmQsV1iffJEfEpZtbM6TYPE6UItA8tjnf *

^^^ bare string - dashboard works

[after adding the relation]

# ceph config dump | grep 'dashboard.*KEY'
mgr advanced mgr/dashboard/RGW_API_ACCESS_KEY {'juju-5e2cd5-0-lxd-2': '8OHNPOQMYY1FEUGAQZL2', 'juju-5e2cd5-1-lxd-3': '8OHNPOQMYY1FEUGAQZL2', 'juju-5e2cd5-2-lxd-2': '8OHNPOQMYY1FEUGAQZL2'} *
mgr advanced mgr/dashboard/RGW_API_SECRET_KEY {'juju-5e2cd5-0-lxd-2': 'I8Gb46kpqCmdBdsCNEx5bhOuEwnOGEtIb73rOK8T', 'juju-5e2cd5-1-lxd-3': 'I8Gb46kpqCmdBdsCNEx5bhOuEwnOGEtIb73rOK8T', 'juju-5e2cd5-2-lxd-2': 'I8Gb46kpqCmdBdsCNEx5bhOuEwnOGEtIb73rOK8T'} *

^^^ dictionary - dashboard doesn't work with "Credentials not found for RGW Daemon"

And according to Samuel, due to the upstream change for Ceph >= 17 (Quincy), the dictionary the charm generates and the dictionary the ceph dashboard expects are different because of daemon_name vs realm_name.
https://github.com/ceph/ceph/commit/0fcf0a7827cf4e8748a382613f9c8d1715c4a1e8#diff-93a9b99949ece1974c8b2d436c5cb0dea338a8352920418249de9b3ece1d156fL285-L297