Wherever the tool lives, it has to be tailored to a specific Ceph
(major) version, e.g. "Luminous" or "Nautilus". As the adjective "major"
indicates, from one major version to another, major changes take place.
This is not accurate for ceph-volume, as we are in a position where we
need to backport every feature. What exists in the master branch
exists all the way back to Luminous, which requires us to deal with
the changes in APIs (e.g. from Luminous to Mimic).
I would argue that c-v is not a special case here. To the extent that
you have decided that its worth the backporting effort to maintain
feature parity across multiple major versions, then c-v features are
being backported, but c-v is not the only Ceph component where feature
backporting takes place. This practice is fairly commonplace in other
Ceph components as well, and when the decision to backport is made,
someone always has to shoulder the maintenance burden for the lifetime
of the major version.
Case in point: the Jewel ceph-volume, like the rest of Jewel, is not
getting any new features - or any backports at all for that matter -
because Jewel has been declared EOL.
For all features that get backported, the "major change" from one stable
version of Ceph to the next is just that: the "next" version of the
feature supports the corresponding version of Ceph.
Nathan
