ntp is contraindicated in 18.04 and later

The ceph-radosgw charm installs the ntp package (unless it's running in a container).

The ntp provides ntpd which I understand doesn't get security updates in bionic or newer releases.

Additionally, in most deployments we have the ntp charm which recommends chrony. The ntp charm likely will install chrony after the ceph-radosgw charm installs ntp. The latter will get removed. However, as soon as something triggers the config-changed hook, the ceph-radosgw charm will install ntp and remove chrony. We'll go back the other way if/when the ntp charm is upgraded.

Can we make the charm intelligent about not installing ntp if chrony is already installed?

It might also be a good idea to make the charm pick the package conditionally, like how the ntp charm does it, chosing chrony if centos or ubuntu bionic or later. Everything else gets ntp.

Or maybe it would be better to remove the ntp package requirement altogether and instead require the ntp subordinate charm? I'm not sure how one would do this.